ACUS01 KWNS 161232
SWODY1
SPC AC 161230

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0730 AM CDT Wed Jul 16 2025

Valid 161300Z - 171200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE MIDWEST/GREAT LAKES AND CENTRAL HIGH PLAINS...

...SUMMARY...
Scattered strong to severe thunderstorms are possible this afternoon
and evening from parts of the central High Plains to the Great Lakes
and Mid-Atlantic.

...Midwest/Great Lakes...
A well-defined MCV is evident on radar/satellite imagery this
morning over IA. This feature will drift east-northeastward today
across the Midwest and Great Lakes, eventually reaching southern
Ontario tonight. A related surface low will develop from IA to
southern WI and Lake Michigan this afternoon/evening, with the
primary synoptic front farther north in WI. Diurnal heating of a
rather moist low-level airmass will likely yield around 1000-2500
J/kg of MLCAPE across southern WI into northern/central IL (locally
stronger with southward extent). The modestly enhanced low/mid-level
winds associated with the MCV should support around 30-40 kt of
deep-layer shear, sufficient for organized severe thunderstorms.

Current expectations are for a band of semi-discrete thunderstorms
to develop across eastern IA into northern IL and southern/central
WI by early to mid afternoon as large-scale ascent attendant to the
MCV overspreads the destabilizing warm sector. Some of this activity
could be supercellular initially and pose a threat for isolated
severe hail along with damaging winds. With time late this afternoon
and evening, gradual upscale growth into a bowing cluster should
occur, with a greater risk for severe/damaging winds towards Lake
Michigan and parts of southern Lower MI. Although low-level flow and
related shear is not forecast to become overly strong this
afternoon, it should be sufficient for some low-level updraft
rotation and perhaps a few tornadoes, particularly across parts of
southern WI/northern IL where semi-discrete convection may occur.

...Ohio Valley/Mid-Atlantic...
A weak mid-level shortwave trough located over the OH Valley this
morning will advance northeastward today to the northern
Mid-Atlantic/NY. Recent visible satellite imagery this morning shows considerable cloud cover present with this feature, along with some
low clouds downstream. Even so, filtered daytime heating of a
seasonably moist airmass should support the development of weak to
locally moderate instability by this afternoon. Poor lapse rates
aloft may tend to inhibit stronger updrafts to some extent, but
marginal deep-layer shear (generally around 20-30 kt) should still
support some degree of convective organization. Loosely organized
clusters and occasional cells may pose an isolated threat for
damaging winds as they spread generally east-northeastward across
parts of the OH Valley and Mid-Atlantic this afternoon/evening.
Confidence in a more concentrated corridor of damaging winds remains
too low to include greater severe probabilities at this time.

...Central Plains to Northern Missouri...
A convectively reinforced surface front should stall by this
afternoon across KS into eastern CO, with a modest low-level upslope
flow regime occurring across the Front Range/central High Plains. On
the southern periphery of an upper trough moving eastward over the northern/central Plains, thunderstorms should develop by early
afternoon over the higher terrain of the central Rockies. This
convection is forecast to move eastward into the adjacent High
Plains through the rest of the afternoon, and continuing through the
evening. The post-frontal airmass should only modestly destabilize,
but enough instability and the presence of steepened lapse rates
aloft are forecast to support robust updrafts. Weak low-level flow
veering to westerly and gradually strengthening with height at
mid/upper levels will likely foster around 35-45 kt of deep-layer
shear. This will easily support supercells and associated large hail
threat with the initial development. Some potential for upscale
growth into a loosely organized cluster is possible across southeast
CO and vicinity this evening along/near the stalled surface front.
If this occurs, then severe winds would become the primary risk.

Farther east across KS into northern MO, isolated convection may
develop through peak afternoon heating along the front. While
deep-layer shear is forecast to remain fairly modest, strong
instability and steep mid-level lapse rates could still support
occasional severe hail/wind with the more robust cores that can be
sustained. Additional convection may develop along/north of the
front this evening in a low-level warm advection regime, while also
posing an isolated severe threat.

...Central Gulf Coast...
Convection offshore from the central Gulf Coast remains disorganized
this morning, as a weak surface low (Invest 93L) remains along/near
the coast of the FL Panhandle. Regardless of potential tropical
development (reference latest NHC forecast), modest enhancement to
the low-level wind field should occur as this feature tracks towards coastal/southeast LA by early Thursday morning. Thunderstorms should occasionally spread inland along/near the central Gulf Coast through
the period, but overall severe potential still appears too limited
to introduce a Marginal Risk with this update.

..Gleason/Bentley.. 07/16/2025

$$

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ACUS01 KWNS 161629
SWODY1
SPC AC 161627

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1127 AM CDT Wed Jul 16 2025

Valid 161630Z - 171200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE MIDWEST AND CENTRAL HIGH PLAINS...

...SUMMARY...
Scattered severe thunderstorms are possible this afternoon and
evening over parts of the Midwest and central High Plains.

...Midwest/Great Lakes...
Late morning radar/satellite imagery shows an MCV over northeast IA
co-located with a 1007-mb surface low. A front is draped from
northeast to southwest and is forecast to gradually push eastward
during the day. The frontal segment east-northeast of the low will
remain quasi-stationary and serve as the northern delimiter of a
surface-based warm sector. Continued heating of a moist boundary
layer will contribute to 1000-2500 J/kg of MLCAPE across central WI
into northern/central IL. The modestly enhanced low/mid-level
winds associated with the MCV will yield 30-40 kt of effective shear---supporting rotation with a few of the stronger updrafts this
afternoon.

Semi-discrete thunderstorms developing in a north-south band will
likely continue to intensify as ascent overspreads the warm sector
over WI and far northern IL. A few supercells are possible with an
attendant risk for all hazards. With time late this afternoon
and evening, gradual upscale growth into a bowing cluster should
occur, with a greater risk for severe/damaging winds towards Lake
Michigan and parts of southern Lower MI.

...Central High Plains to Northern Missouri...
Indications late this morning are that a convectively reinforced
surface front will become stationary across KS into eastern CO with
moist, upslope flow into the central High Plains north of the
boundary. The southern periphery of stronger mid-level westerly
flow will glance the central High Plains where strongly veering flow
will result in deep-layer shear supporting storm organization.
Although heating will be partially thwarted by persistent low-level
cloud cover through at least the early afternoon, sufficient heating
is expected to result in scattered to widespread thunderstorms
eventually developing during the late afternoon. A few supercells
are possible with an accompanying threat for large hail and
localized severe gusts. As storm coverage increases, upscale growth
into an organized cluster is probable during the evening. Severe
gusts will likely become the primary hazard during the evening as
the mode becomes more linear and outflow dominant.

Farther east across KS into northern MO, isolated convection may
develop through peak afternoon heating along the front. While
deep-layer shear is forecast to remain fairly modest, strong
instability and steep mid-level lapse rates could still support
occasional severe hail/wind with the more robust cores that can be
sustained. Additional convection may develop along/north of the
front this evening in a low-level warm advection regime, while also
posing an isolated severe threat.

...Ohio Valley/Mid-Atlantic...
A couple of MCVs will focus scattered strong to locally severe
thunderstorms mainly this afternoon and early evening. Relatively
weak lapse rates and modest deep-layer shear will tend to limit
storm organization. Nonetheless, sporadic and isolated bouts of
strong to damaging gusts are possible with the stronger
thunderstorms through early evening.

...Central Gulf Coast...
Modest strengthening of the low-level wind field is expected as a
weak tropical disturbance migrates westward over the northern Gulf
of America. However, model guidance shows hodographs generally
remaining diminutive in size, implying disorganized storm modes
(mainly outflow dominant structures in the form of bands and small
clusters).

..Smith/Lyons.. 07/16/2025

$$

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ACUS01 KWNS 161930
SWODY1
SPC AC 161929

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0229 PM CDT Wed Jul 16 2025

Valid 162000Z - 171200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
THE GREAT LAKES AND CENTRAL HIGH PLAINS...

...SUMMARY...
Scattered severe thunderstorms remain possible this afternoon and
evening over parts of the Midwest and central High Plains.

...20Z Update...
The previous forecast (see below) remains largely on track. The main
changes made to the 20Z Day 1 Convective Outlook update was to trim
severe probabilities behind the main band of convection across the
Upper MS Valley, and to trim thunderstorm probabilities over parts
of the north-central CONUS, amid waning buoyancy.

..Squitieri.. 07/16/2025

.PREV DISCUSSION... /ISSUED 1127 AM CDT Wed Jul 16 2025/

...Midwest/Great Lakes...
Late morning radar/satellite imagery shows an MCV over northeast IA
co-located with a 1007-mb surface low. A front is draped from
northeast to southwest and is forecast to gradually push eastward
during the day. The frontal segment east-northeast of the low will
remain quasi-stationary and serve as the northern delimiter of a
surface-based warm sector. Continued heating of a moist boundary
layer will contribute to 1000-2500 J/kg of MLCAPE across central WI
into northern/central IL. The modestly enhanced low/mid-level
winds associated with the MCV will yield 30-40 kt of effective shear---supporting rotation with a few of the stronger updrafts this
afternoon.

Semi-discrete thunderstorms developing in a north-south band will
likely continue to intensify as ascent overspreads the warm sector
over WI and far northern IL. A few supercells are possible with an
attendant risk for all hazards. With time late this afternoon
and evening, gradual upscale growth into a bowing cluster should
occur, with a greater risk for severe/damaging winds towards Lake
Michigan and parts of southern Lower MI.

...Central High Plains to Northern Missouri...
Indications late this morning are that a convectively reinforced
surface front will become stationary across KS into eastern CO with
moist, upslope flow into the central High Plains north of the
boundary. The southern periphery of stronger mid-level westerly
flow will glance the central High Plains where strongly veering flow
will result in deep-layer shear supporting storm organization.
Although heating will be partially thwarted by persistent low-level
cloud cover through at least the early afternoon, sufficient heating
is expected to result in scattered to widespread thunderstorms
eventually developing during the late afternoon. A few supercells
are possible with an accompanying threat for large hail and
localized severe gusts. As storm coverage increases, upscale growth
into an organized cluster is probable during the evening. Severe
gusts will likely become the primary hazard during the evening as
the mode becomes more linear and outflow dominant.

Farther east across KS into northern MO, isolated convection may
develop through peak afternoon heating along the front. While
deep-layer shear is forecast to remain fairly modest, strong
instability and steep mid-level lapse rates could still support
occasional severe hail/wind with the more robust cores that can be
sustained. Additional convection may develop along/north of the
front this evening in a low-level warm advection regime, while also
posing an isolated severe threat.

...Ohio Valley/Mid-Atlantic...
A couple of MCVs will focus scattered strong to locally severe
thunderstorms mainly this afternoon and early evening. Relatively
weak lapse rates and modest deep-layer shear will tend to limit
storm organization. Nonetheless, sporadic and isolated bouts of
strong to damaging gusts are possible with the stronger
thunderstorms through early evening.

...Central Gulf Coast...
Modest strengthening of the low-level wind field is expected as a
weak tropical disturbance migrates westward over the northern Gulf
of America. However, model guidance shows hodographs generally
remaining diminutive in size, implying disorganized storm modes
(mainly outflow dominant structures in the form of bands and small
clusters).

$$

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ACUS01 KWNS 170051
SWODY1
SPC AC 170050

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0750 PM CDT Wed Jul 16 2025

Valid 170100Z - 171200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM EASTERN CO
TO THE LOWER MO VALLEY...LOWER MI TO THE LOWER OH VALLEY...AND THE MID-ATLANTIC...

...SUMMARY...
Isolated severe thunderstorms remain possible tonight across eastern
Colorado to the Lower Missouri Valley. Isolated damaging winds
remain possible this evening across parts of the Midwest and the
Mid-Atlantic States.

...Eastern CO to the Lower MO Valley...
A trio of rather widely-spaced and recently weakening supercells are
ongoing across eastern CO to southwest KS. With pronounced MLCIN
downstream, that will further increase nocturnally, these
surface-based storms should diminish. Widespread elevated convection
is expected across northern KS into the Lower MO Valley overnight,
north of the southward-sagging cold front. Marginal severe hail will
be possible with initial updrafts before clustering in a largely west/east-orientation. Modest effective bulk shear will limit the
overall threat.

...Lower MI/Lower OH Valley to the Mid-Atlantic States...
A generally weakening broken line of convection is ongoing from
western Lower MI to southern IL. The MI portion has shown some
recent uptick, closer to the MCV over central Lake MI. Adequate
deep-layer shear and the recent convective increase may foster a
sporadic damaging wind threat. But the downstream airmass of weak
lapse rates and MLCAPE, as sampled by the 00Z DTX/APX soundings,
will marginalize severe potential tonight.

Farther east, slow-moving thunderstorms will drift east and/or
weaken across parts of the Mid-Atlantic States tonight. But pockets
of moderate buoyancy and modest deep-layer shear could support
localized damaging winds for a few more hours.

..Grams.. 07/17/2025

$$

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ACUS01 KWNS 170552
SWODY1
SPC AC 170550

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1250 AM CDT Thu Jul 17 2025

Valid 171200Z - 181200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN NORTHERN PARTS
OF THE GREAT PLAINS AND NEW ENGLAND...

...SUMMARY...
A confined corridor of large hail and severe gusts may occur from
north-central Montana to southwest North Dakota this evening.
Scattered damaging winds and a brief tornado are possible across
northern New England this afternoon. Isolated/sporadic damaging
winds are also possible across a broad swath of the
Northeast/Mid-Atlantic to the southern High Plains.

...Northern Great Plains...
A confined corridor of supercell potential is evident across
north-central MT to southwest ND this evening. A positive-tilt
shortwave trough over the southern Canadian Rockies will progress
east along the international border with MT/ND. 00Z HREF guidance is
consistent in indicating mid-afternoon storm development over
southwest AB. A confined plume of weak buoyancy initially ahead of
this activity should temper intensity as it spreads east-southeast
into north-central MT by late afternoon. But favorably timed
strengthening of a 500-mb westerly jetlet will aid in hodograph
elongation. This could support a long-lived/long-track supercell
during the evening, impinging on the nose of moderate MLCAPE across
southeast MT. Modest mid-level lapse rates and a cooler-than-normal
boundary layer should be the primary limiting factor to greater
hail/wind magnitudes. But enough signal exists to warrant a narrow
level 2-SLGT risk for hail. Low-probability hail/wind threats may
persist along the ND/SD border area overnight.

...New England/Northeast...
A large MCV over Lower MI will become further absorbed into a
shortwave trough that will progress from the Upper Great Lakes to
the ON/QC border area by early evening. This will help broaden a
swath of enhanced 850-700 mb west-southwesterlies from PA/NJ north.
But further weakening of already marginal mid-level lapse rates,
owing to the influence of the MCV, should yield a pocket of 500-mb
temperatures warming to -4 C in the Hudson Valley vicinity by late
afternoon. This will likely limit convective coverage across the
Northeast to southern New England vicinity. Scattered, mainly
discrete, convection is anticipated along the QC border across
northern New England. A few weak supercells are probable, capable of
mainly damaging winds and a brief tornado.

...Lower Mid-Atlantic to the southern High Plains...
Scattered to widespread thunderstorms are expected west of the
Appalachians along a large-scale west/east-oriented convective
outflow, augmented by a surface cold front stalling in the southern
High Plains. Ample buoyancy south of the outflow/front will support
sporadic wet microbursts. Modest deep-layer shear and warm 500-mb
temperatures should modulate overall organization/coverage. Isolated
damaging winds are also expected east of the central Appalachians,
where storm coverage should be reduced but downbursts are possible.

..Grams/Thornton.. 07/17/2025

$$

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ACUS01 KWNS 171237
SWODY1
SPC AC 171235

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0735 AM CDT Thu Jul 17 2025

Valid 171300Z - 181200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHEAST AND NORTHERN HIGH PLAINS...

...SUMMARY...
Scattered damaging winds and a brief tornado are possible across
northern New England this afternoon. Isolated/sporadic damaging
winds may also occur across a broad swath of the
Northeast/Mid-Atlantic to the southern High Plains. A confined
corridor of large hail and severe gusts appears possible from
north-central Montana to southwest North Dakota this evening.

...Northeast...
The Slight Risk has been maintained across this region with no
changes. A shortwave trough will move northeastward from the Upper
Great Lakes to the Ontario/Quebec border vicinity by this evening. A
broad swath of enhanced 850-700 mb west-southwesterly winds is
forecast from PA/NJ northward into New England. Further weakening of
already poor mid-level lapse rates is anticipated across parts of
southern NY into southern New England. This may tend to limit
convective coverage across the northern Mid-Atlantic to southern New
England vicinity. But, farther north and in closer proximity to
ascent associated with the approaching mid-level shortwave trough,
scattered robust convection is anticipated this afternoon along the
Quebec border across northern New England. Sufficient instability
and deep-layer shear are forecast across this region to support a
mix of multicells and perhaps marginal supercells. Given the
enhanced low/mid-level flow, scattered damaging winds should be the
main threat with this activity as it moves generally
east-northeastward through the early evening, before eventually
weakening as it approaches the coast. Enough low-level hodograph enlargement/curvature may also be present to support some risk for a
tornado or two.

...Mid-Atlantic to the Southern High Plains...
Extensive convection is ongoing this morning across
south-central/southeast KS into MO. This activity should generally
remain sub-severe, but it will help reinforce a front that is
expected to gradually sag southward and eventually stall across the
mid MS Valley to southern Plains today. Scattered to numerous
thunderstorms are expected to develop west of the Appalachians along
this boundary later this afternoon as diurnal heating occurs.
Moderate to strong instability amid steepened low-level rates
along/south of the outflow/front should support sporadic wet
microbursts. Isolated hail will be possible with thunderstorms in
the post-frontal upslope flow regime across parts of the southern
High Plains. But, modest deep-layer shear and warm temperatures
aloft across all these regions should temper the overall
intensity/coverage of severe convection. Isolated damaging winds may
also occur with thunderstorms that develop east of the central
Appalachians this afternoon, even though coverage should be somewhat
less.

...Northern Plains...
A narrow corridor of supercell potential remains evident across
north-central MT to southwest ND, mainly this evening. A positively
tilted mid-level shortwave trough over the southern Canadian Rockies
will progress eastward along the international border with MT/ND
today. Mid to late afternoon convective initiation should occur over
parts of southwest Alberta in association with this feature. A
confined plume of weak buoyancy ahead of this activity should
initially temper updraft intensity as it spreads east-southeastward
into north-central MT by late afternoon. But, favorably timed
strengthening of a 500-mb westerly jet over MT will aid in hodograph
elongation at mid/upper levels this evening. This could support a
long-lived supercell or two during the evening, impinging on the
nose of moderate instability that should be present across southeast
MT. Large hail should be the main threat with these supercells if
they can be maintained. An isolated hail/wind risk may persist along
the ND/SD border vicinity overnight.

..Gleason/Bentley.. 07/17/2025

$$

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ACUS01 KWNS 171627
SWODY1
SPC AC 171625

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1125 AM CDT Thu Jul 17 2025

Valid 171630Z - 181200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS NORTHERN
NEW ENGLAND AND THE NORTHERN HIGH PLAINS...

...SUMMARY...
Scattered damaging winds and a tornado are possible across northern
New England this afternoon. A confined corridor of large hail and
severe gusts appears possible from north-central Montana to
southwest North Dakota this evening.

...Northeast...
Midday visible-satellite imagery shows cloud breaks and surface
observations show warming temperatures which imply a destabilizing
airmass. A lead, convectively enhanced disturbance evident in
radar/satellite imagery, is moving east across southern Quebec,
while an upstream larger-scale mid-level trough continues eastward
across Ontario and into Quebec later today. A cyclone will develop
northeast from eastern Ontario into eastern Quebec while a cold
front pushes through the Lower Great Lakes and through much of the
Northeast through mid evening. The deep moisture through much of
the troposphere and weak lapse rate profiles, which were sampled by
the 12 UTC Buffalo and Albany, NY raobs, will undergo moderate
destabilization by early to mid afternoon. Although forcing for
ascent will favor Quebec into northern New England, scattered
thunderstorms will likely develop from Maine southward into southern
New England. The greatest potential for some organized storms will
favor northern New England where stronger effective shear (30-40 kt)
and adequate buoyancy will promote a wind-damage threat with the
stronger storms. Forecast sounding over northern Maine show
enlarged hodographs for a few hours, which may aid in low-level
mesocyclone development and perhaps a risk for a tornado. Lower
coverage of severe is forecast farther south where weaker shear will
tend to limit storm intensity. The severe activity will likely
diminish by the early to mid evening.

...Northern High Plains...
Model guidance continues to show a focused corridor of supercell
thunderstorm potential from north-central MT to southwest ND, mainly
this evening. Water-vapor imagery shows a mid-level shortwave
trough rotating southeastward across the southern part of the
Canadian Rockies moving towards the northern High Plains. Forecast
soundings this afternoon show elongated hodographs amidst modest
buoyancy, which would support the development of a supercell or two
during the evening. Large hail is the primary hazard with this
activity but severe gusts may occur on a localized basis. An
isolated hail/wind risk may persist along the ND/SD border vicinity
overnight.

...Mid-Atlantic to the Southern High Plains...
A surface front draped over the south-central Plains
east-northeastward into the mid MS/OH Valleys will focus scattered
thunderstorm activity this afternoon. The eastern part of this
broader region over the Mid-Atlantic into the OH Valley will be
displaced from the mid-level trough over influencing storm activity
over the Northeast. A remnant MCV and outflow from overnight storms
in the MO/KS/OK vicinity will aid in developing storms and perhaps
localized threats for sporadic hail/wind mainly this afternoon.
Isolated damaging winds may also occur with thunderstorms that
develop east of the central Appalachians this afternoon, even though
coverage should be somewhat less.

..Smith/Lyons.. 07/17/2025

$$

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ACUS01 KWNS 171940
SWODY1
SPC AC 171939

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0239 PM CDT Thu Jul 17 2025

Valid 172000Z - 181200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
THE NORTHERN HIGH PLAINS AND NORTHERN NEW ENGLAND...

...SUMMARY...
Scattered damaging winds and a tornado remain possible across
northern New England this afternoon. A confined corridor of large
hail and severe gusts appears possible from north-central Montana to
southwest North Dakota this evening.

...20Z Update...
The primary change to the outlook was to add 15 percent wind
probabilities across portions of northern into eastern Montana.
Here, supercells and/or short line segments should develop amid
strong mid/upper flow overspreading the region. Downward momentum
transport of this stronger flow aloft may promote efficient severe
gust production with the stronger storms. Otherwise, the previous
forecast (see below) remains on track, with minor changes made to thunder/severe probabilities to reflect the latest observations and
guidance consensus.

..Squitieri.. 07/17/2025

.PREV DISCUSSION... /ISSUED 1125 AM CDT Thu Jul 17 2025/

...Northeast...
Midday visible-satellite imagery shows cloud breaks and surface
observations show warming temperatures which imply a destabilizing
airmass. A lead, convectively enhanced disturbance evident in
radar/satellite imagery, is moving east across southern Quebec,
while an upstream larger-scale mid-level trough continues eastward
across Ontario and into Quebec later today. A cyclone will develop
northeast from eastern Ontario into eastern Quebec while a cold
front pushes through the Lower Great Lakes and through much of the
Northeast through mid evening. The deep moisture through much of
the troposphere and weak lapse rate profiles, which were sampled by
the 12 UTC Buffalo and Albany, NY raobs, will undergo moderate
destabilization by early to mid afternoon. Although forcing for
ascent will favor Quebec into northern New England, scattered
thunderstorms will likely develop from Maine southward into southern
New England. The greatest potential for some organized storms will
favor northern New England where stronger effective shear (30-40 kt)
and adequate buoyancy will promote a wind-damage threat with the
stronger storms. Forecast sounding over northern Maine show
enlarged hodographs for a few hours, which may aid in low-level
mesocyclone development and perhaps a risk for a tornado. Lower
coverage of severe is forecast farther south where weaker shear will
tend to limit storm intensity. The severe activity will likely
diminish by the early to mid evening.

...Northern High Plains...
Model guidance continues to show a focused corridor of supercell
thunderstorm potential from north-central MT to southwest ND, mainly
this evening. Water-vapor imagery shows a mid-level shortwave
trough rotating southeastward across the southern part of the
Canadian Rockies moving towards the northern High Plains. Forecast
soundings this afternoon show elongated hodographs amidst modest
buoyancy, which would support the development of a supercell or two
during the evening. Large hail is the primary hazard with this
activity but severe gusts may occur on a localized basis. An
isolated hail/wind risk may persist along the ND/SD border vicinity
overnight.

...Mid-Atlantic to the Southern High Plains...
A surface front draped over the south-central Plains
east-northeastward into the mid MS/OH Valleys will focus scattered
thunderstorm activity this afternoon. The eastern part of this
broader region over the Mid-Atlantic into the OH Valley will be
displaced from the mid-level trough over influencing storm activity
over the Northeast. A remnant MCV and outflow from overnight storms
in the MO/KS/OK vicinity will aid in developing storms and perhaps
localized threats for sporadic hail/wind mainly this afternoon.
Isolated damaging winds may also occur with thunderstorms that
develop east of the central Appalachians this afternoon, even though
coverage should be somewhat less.

$$

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ACUS01 KWNS 180049
SWODY1
SPC AC 180047

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0747 PM CDT Thu Jul 17 2025

Valid 180100Z - 181200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN EASTERN MT TO
FAR SOUTHWEST ND...

...SUMMARY...
A couple supercells will remain capable of large hail and severe
gusts through about midnight across eastern Montana.

...Northern Great Plains...
A couple supercells are ongoing over north-central MT with a history
of measured severe gusts and severe hail signatures per MRMS MESH.
This activity should persist southeastward through at least late
evening amid strong effective bulk shear but weak buoyancy and
modest mid-level lapse rates per the 00Z GGW sounding. Most guidance
outside of the RRFS suggest that convection will remain as discrete
supercells before eventually waning as it impinges on minimal
surface-based instability near the MT/ND border. With such a cool
and dry boundary layer per surface observations across far eastern
MT into ND, the overall severe threat should diminish towards
midnight. Elevated convection should develop across parts of the
Dakotas overnight, with weak MUCAPE marginalizing severe potential.

...Southern High Plains...
A slow-moving, loosely organized cluster is ongoing east-southeast
of the Sangre de Cristo Mountains in northeast NM. While the
boundary layer is climatologically cool, it is moist and moderately
unstable (per the 00Z AMA sounding), amid persistent low-level
easterlies. This upslope flow regime should support cluster
maintenance through late evening before gradually waning overnight.
While heavy rain is the primary hazard (per WPC ERO SLGT risk), a
few strong to marginal severe gusts and small hail remain possible.

...Northern ME...
Convection has largely waned across New England and should continue
to do so over the next hour. With some lingering deep convection
across northern ME, a moist boundary layer and still sufficient
deep-layer shear (per the CBW VWP) may support a weakly rotating
storm or two before convection spreads entirely into NB.

...Eastern OK to the Delmarva...
A couple microbursts capable of strong gusts may still occur in yet
to be overturned areas across a broad swath from the Ozarks to the
Mid-Atlantic Coast. With modest deep-layer shear and nocturnal
boundary-layer cooling, severe probabilities appear negligible.

..Grams.. 07/18/2025

$$

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ACUS01 KWNS 180546
SWODY1
SPC AC 180545

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1245 AM CDT Fri Jul 18 2025

Valid 181200Z - 191200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN PARTS OF VA/NC
AND NE/SD/MN/IA...

...SUMMARY...
Scattered severe thunderstorms with large hail, damaging winds, and
a few tornadoes are possible across parts of the Corn Belt in Iowa,
Minnesota, Nebraska, and South Dakota this evening into tonight.
Scattered damaging winds are possible across parts of Virginia and
northern North Carolina this afternoon.

...SD/MN/IA/NE...
A low-amplitude shortwave impulse along the international border
over the northern Great Plains will progress across the Upper
Midwest/Great Lakes and ON. A belt of seasonably strong mid-level
westerlies should be centered this afternoon from central MN to Lake
Huron. Elevated convection is expected to be ongoing at 12Z across
parts of the eastern Dakotas into northern MN ahead of the mid-level
impulse, amid a low-level warm theta-e advection regime. As this
overspreads a preceding cool/dry surface airmass over the Upper
Midwest, pronounced differential diabatic surface heating will
strengthen a baroclinic zone across southeast SD bisecting IA to the
southeast by late afternoon. Thunderstorm development in this time
frame should be confined to along/northeast of the surface warm
front across far eastern SD and southern MN. Large-scale ascent
appears nebulous, but a strengthening low-level jet should aid in
convection flanking to the southwest across the Mid-MO Valley during
the evening. This may merge with high-based convection shifting east
from western NE.

Deep-layer shear will be sufficient for initial supercells that will
probably grow upscale into multiple clusters and/or an MCS tonight.
The latter may accelerate east-southeast for a time in the western
IA vicinity before weakening during the early morning. A mix of all
severe hazards are possible in this setup with hail being favored
early and wind later. Moderately enlarged low-level hodographs
should also support a tornado threat with any sustained supercell to
QLCS evolution.

...VA/NC...
00Z HREF guidance supports scattered to numerous thunderstorms this
afternoon with transient organizational structures that should be
sufficient for a scattered damaging wind threat. This appears to be
largely in response to the eastward progression of an MCV currently
near the IN/OH/KY border. A compact belt of enhanced mid-level
westerlies should overspread the northern periphery of ample MLCAPE
emanating from the South Atlantic Coastal Plain. Multicell clusters
that can progress towards a warmer/deeper boundary layer across the
Piedmont and Coastal Plain should produce strong to sporadic severe
gusts through early evening.

..Grams/Wendt.. 07/18/2025

$$

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ACUS01 KWNS 181244
SWODY1
SPC AC 181243

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0743 AM CDT Fri Jul 18 2025

Valid 181300Z - 191200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF VIRGINIA/NORTH CAROLINA...AND PARTS OF CENTRAL/EASTERN
NEBRASKA...SOUTHEAST SOUTH DAKOTA...SOUTHWEST MINNESOTA...AND
WESTERN/CENTRAL IOWA...

...SUMMARY...
Scattered severe thunderstorms with large hail, damaging winds, and
a few tornadoes are possible across parts of the Corn Belt in Iowa,
Minnesota, Nebraska, and South Dakota this evening into tonight.
Scattered damaging winds are possible across parts of Virginia and
North Carolina this afternoon.

...Virginia/North Carolina to the Mid-South...
A generally west-east oriented quasi-stationary front reinforced by
outflow from earlier convection should serve as a low-level forcing
mechanism for thunderstorm development this afternoon from parts of
VA/NC westward to the Mid-South and vicinity. A seasonably moist
airmass will be present today along/south of this front, with
surface dewpoints generally ranging from the upper 60s in higher
elevations to mid 70s elsewhere. Even though mid-level lapse rates
are expected to remain rather modest, ample daytime heating of the
moist low-level airmass will contribute to sizable MLCAPE by early
to mid afternoon. With a subtropical anticyclone centered off the
Southeast Atlantic Coast and stronger flow aloft associated with
various mid-level perturbations expected to remain over the Great Lakes/Northeast, large-scale ascent in the vicinity of the surface
front will be nebulous at best.

Regardless, scattered to numerous thunderstorms should develop
along/near this boundary through the afternoon, while spreading
generally eastward this evening. With modest mid-level westerly flow
forecast, deep-layer shear appears marginal for thunderstorm
organization. The greatest threat for scattered damaging winds
should focus across parts of VA/NC this afternoon and early evening,
where semi-organized clusters and short line segments appear
possible given slightly stronger deep-layer shear. Otherwise,
isolated damaging winds may occur even with less organized
convection farther west towards parts of the TN Valley/Mid-South, as
steepened low-level lapse rates potentially support microbursts.
There does appear to be a gap in scattered convective coverage
across parts of MO and vicinity, where the Marginal Risk has been
removed with this update.

...South Dakota/Nebraska into Minnesota/Iowa...
Elevated convection across parts of SD may continue to pose an
isolated hail threat this morning, before it eventually weakens with
the gradual lessening of a southerly low-level jet. A belt of strong
westerly mid-level flow will remain in place over the northern tier
of the CONUS from MT eastward towards the Great Lakes. Gradual
low-level moistening is forecast through this evening ahead of a
weak front forecast to be in place over the eastern Dakotas into
western NE. Diurnal heating and modestly steepened mid-level lapse
rates will contribute to moderate to strong MLCAPE across parts of
NE/southeast SD into IA. But, nebulous forcing for ascent and
residual capping should tend to suppress surface-based convective
development across these areas for much of the day. Occasional
severe hail may occur with mainly elevated convection to the north
of the front in MN.

A gradually strengthening southerly low-level jet this evening
(mainly after 00Z) should aid in convective initiation along/near
the front from central/northeast NE into southeast SD/southwest MN.
Various NAM/RAP forecast soundings across this region suggest ample
instability and strong deep-layer shear will be present to support
supercells with attendant large hail threat initially. Low-level
shear should also be strong enough for a tornado threat with these
supercells, although there may be a fairly narrow spatial/temporal
window for convection to remain discrete this evening. Upscale
growth into a bowing cluster should occur through mid to late
evening, with a threat for mainly scattered severe/damaging winds as
this convection tracks into parts of IA overnight, before eventually
weakening early Saturday morning.

...Great Basin into Wyoming and Far Southern Montana...
Initially high-based convection should develop this afternoon across
parts of the Great Basin into WY as modest ascent associated with a weak/low-amplitude mid-level impulse spreads eastward across these
areas. While low-level moisture and deep-layer shear will remain
limited, steepened low/mid-level lapse rates amid a very well-mixed
boundary layer should support isolated severe gusts with any
thunderstorms that can be sustained amid weak instability. Somewhat
greater low-level moisture should be present this afternoon across
parts of southern MT into northern/eastern WY, generally along/east
of the Bighorn/Laramie Mountains. Isolated severe hail may occur
with marginal supercells given greater instability/shear forecast
across these areas.

..Gleason/Bentley.. 07/18/2025

$$

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ACUS01 KWNS 181607
SWODY1
SPC AC 181606

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1106 AM CDT Fri Jul 18 2025

Valid 181630Z - 191200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
VIRGINIA AND NORTH CAROLINA...AND WESTERN PARTS OF THE MIDWEST...

...SUMMARY...
Scattered severe thunderstorms with large hail, damaging winds, and
a couple of tornadoes are possible across parts of the Corn Belt in
Iowa, Minnesota, Nebraska, and South Dakota this evening into
tonight. Scattered damaging winds are possible across parts of
Virginia and North Carolina this afternoon.

...Virginia/North Carolina to the Mid-South...
Late morning surface analysis places a stationary front draped from
west to east from the mid MS Valley eastward into the Mid-Atlantic
states. Visible satellite/radar mosaic imagery shows a couple of
weak MCVs moving east over the northern VA/MD vicinity and over far
eastern KY. The latter disturbance will probably prove instrumental
in aiding storm development across VA into northern NC this
afternoon.

South of the front, rich low-level moisture and heating will act to
offset weak mid-level lapse rates and yield moderate to strong
buoyancy from southeast MO eastward to the Mid-Atlantic coast.
Early indications of a swelling cumulus field over the WV/VA
mountains will gradually evolve into a cluster of storms as
convective inhibition continues to erode through early afternoon.
Other clusters of storms will develop and move west to east given
marginal deep-layer mean westerly flow. Although small hail
0.50-1.00 inch in diameter is possible with the strongest cores, the
primary hazard with the stronger storms will be damaging gusts
(50-65 mph) with the more intense water-loaded downdrafts. This
activity will likely diminish by the early to mid evening.

...South Dakota/Nebraska into Minnesota/Iowa...
Gradual low-level moistening is forecast through this evening ahead
of a weak front forecast to be in place over the eastern Dakotas
into western NE. An initially appreciable capping inversion will
inhibit surface-based storm development until heating gradually
weakens inhibition by late afternoon. A very unstable airmass is
forecast by late afternoon/early evening, but nebulous forcing lends uncertainty in terms of storm development/timing. Models suggest
storms will primarily develop this evening associated with
strengthening low-level theta-e advection. Supercells are possible
early in the convective life cycle with a risk for all hazards,
including the possibility for a couple of tornadoes, but large hail
may be the main hazard. Upscale growth into a cluster or MCS is
possible near the terminus of a southwesterly 850-mb LLJ with severe
gusts the becoming the primary threat. Models vary considerably
whether storm intensity is maintained through much of the overnight
and beyond the Day-1 period, or if a gradual diminishing in severe
occurs.

...Great Basin into Wyoming and Far Southern Montana...
Initially high-based convection should develop this afternoon across
parts of the Great Basin into WY as modest ascent associated with a weak/low-amplitude mid-level impulse spreads eastward across these
areas. Steep low/mid-level lapse rates and a deep, very well-mixed
boundary layer should support isolated severe gusts with the
stronger thunderstorms. Somewhat greater low-level moisture should
be present this afternoon across parts of southern MT into
northern/eastern WY, generally along/east of the Bighorn/Laramie
Mountains. Isolated severe hail may occur with marginal supercells
given greater instability/shear forecast across these areas.

..Smith/Weinman.. 07/18/2025

$$

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ACUS01 KWNS 181926
SWODY1
SPC AC 181924

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0224 PM CDT Fri Jul 18 2025

Valid 182000Z - 191200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL PLAINS INTO THE MIDWEST AND PARTS OF THE MID-ATLANTIC...

...SUMMARY...
Scattered severe thunderstorms with large hail, damaging winds, and
a couple of tornadoes are possible across parts of the Corn Belt in
Iowa, Minnesota, Nebraska, and South Dakota this evening into
tonight. Scattered damaging winds are possible across parts of
Virginia and North Carolina this afternoon.

...20Z Update...
The primary change to the Day 1 20Z Convective Outlook update was to
make minor eastward expansions of wind probabilities into eastern
IA, as some of the latest convection allowing guidance depicts an
MCS persisting into this region. Otherwise, the previous forecast
(see below) remains on track, with very small adjustments made to thunder/severe probabilities to account for observational trends
and/or guidance consensus updates.

..Squitieri.. 07/18/2025

.PREV DISCUSSION... /ISSUED 1106 AM CDT Fri Jul 18 2025/

...Virginia/North Carolina to the Mid-South...
Late morning surface analysis places a stationary front draped from
west to east from the mid MS Valley eastward into the Mid-Atlantic
states. Visible satellite/radar mosaic imagery shows a couple of
weak MCVs moving east over the northern VA/MD vicinity and over far
eastern KY. The latter disturbance will probably prove instrumental
in aiding storm development across VA into northern NC this
afternoon.

South of the front, rich low-level moisture and heating will act to
offset weak mid-level lapse rates and yield moderate to strong
buoyancy from southeast MO eastward to the Mid-Atlantic coast.
Early indications of a swelling cumulus field over the WV/VA
mountains will gradually evolve into a cluster of storms as
convective inhibition continues to erode through early afternoon.
Other clusters of storms will develop and move west to east given
marginal deep-layer mean westerly flow. Although small hail
0.50-1.00 inch in diameter is possible with the strongest cores, the
primary hazard with the stronger storms will be damaging gusts
(50-65 mph) with the more intense water-loaded downdrafts. This
activity will likely diminish by the early to mid evening.

...South Dakota/Nebraska into Minnesota/Iowa...
Gradual low-level moistening is forecast through this evening ahead
of a weak front forecast to be in place over the eastern Dakotas
into western NE. An initially appreciable capping inversion will
inhibit surface-based storm development until heating gradually
weakens inhibition by late afternoon. A very unstable airmass is
forecast by late afternoon/early evening, but nebulous forcing lends uncertainty in terms of storm development/timing. Models suggest
storms will primarily develop this evening associated with
strengthening low-level theta-e advection. Supercells are possible
early in the convective life cycle with a risk for all hazards,
including the possibility for a couple of tornadoes, but large hail
may be the main hazard. Upscale growth into a cluster or MCS is
possible near the terminus of a southwesterly 850-mb LLJ with severe
gusts the becoming the primary threat. Models vary considerably
whether storm intensity is maintained through much of the overnight
and beyond the Day-1 period, or if a gradual diminishing in severe
occurs.

...Great Basin into Wyoming and Far Southern Montana...
Initially high-based convection should develop this afternoon across
parts of the Great Basin into WY as modest ascent associated with a weak/low-amplitude mid-level impulse spreads eastward across these
areas. Steep low/mid-level lapse rates and a deep, very well-mixed
boundary layer should support isolated severe gusts with the
stronger thunderstorms. Somewhat greater low-level moisture should
be present this afternoon across parts of southern MT into
northern/eastern WY, generally along/east of the Bighorn/Laramie
Mountains. Isolated severe hail may occur with marginal supercells
given greater instability/shear forecast across these areas.

$$

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ACUS01 KWNS 190048
SWODY1
SPC AC 190047

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0747 PM CDT Fri Jul 18 2025

Valid 190100Z - 191200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN NE/IA TO
SOUTHEAST SD AND SOUTHERN MN...

...SUMMARY...
Scattered severe thunderstorms with large hail, damaging winds, and
a couple of tornadoes are possible across parts of the Corn Belt in
Iowa, Minnesota, Nebraska, and South Dakota tonight.

...NE/IA/SD/MN...
Initial thunderstorms along the eastern SD/southwest MN are expected
to greatly expand to the southwest along a quasi-stationary front
into the central High Plains, as a broad low-level jet strengthens
from the southern High Plains across KS. With a pronounced gradient
in mid/upper-level westerlies from south to north, a complex/messy
convective mode evolution is anticipated with a mix of supercells
evolving into predominantly clusters and a potential MCS overnight.
With a substantial MLCAPE gradient oriented north/south in southern
MN to northwest-southeast across IA, the most intense storms should
remain centered on the Mid-MO Valley through NE. Sufficient
low-level shear amid lower 70s surface dew points will foster some
tornado risk through late evening in the Mid-MO Valley vicinity.
Otherwise, initial large hail threat should transition to
predominantly strong/severe gusts overnight, with a gradual
weakening trend towards dawn in the IA vicinity.

...Eastern NC and southeast VA...
Widely scattered multicell clusters which have produced sporadic
wind damage along with measured strong gusts should continue towards
the coast over the next few hours. This activity should gradually
subside as it encounters pockets of previously overturned air.
Locally damaging winds will remain possible until these clusters
sufficiently weaken.

..Grams.. 07/19/2025

$$

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ACUS01 KWNS 190547
SWODY1
SPC AC 190545

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1245 AM CDT Sat Jul 19 2025

Valid 191200Z - 201200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN PARTS OF THE NORTHERN/CENTRAL GREAT PLAINS...MIDWEST...AND VA VICINITY...

...SUMMARY...
Scattered large to very large hail and severe gusts are possible
across the northern/central Great Plains during the late afternoon
and evening. Scattered damaging winds are possible across parts of
the Midwest and the Lower Mid-Atlantic States into this afternoon. Low-probability tornado potential is also evident in the Midwest and
parts of the Great Plains.

...Northern/central Great Plains...
A favorable setup for discrete supercells is anticipated along a lee
trough from the WY/NE border into eastern MT and far western ND.
While rich boundary-layer moisture will remain confined across
southern NE, a ribbon of increasing moisture will be advected
north-northwest beneath a pronounced EML. A shortwave trough will
eject along the Canadian border across the Northwest. An attendant
belt of 40-45 kt mid-level westerlies will overspread much of MT
into ND, with a separate belt of confluent westerlies across
southeast WY through NE. Deep-layer shear profiles will be conducive
to discrete supercells as initial storms develop during the mid to
late afternoon, with large to very hail possible. Signals for
greater convective coverage along the MT/ND border and in the
western NE vicinity may support a greater than isolated severe gust
threat. With a deeper and hotter boundary layer with southward
extent into KS, upscale growth into a forward-propagating cluster
eastward along the NE/KS border is possible this evening.

...Midwest...
An MCS will likely be ongoing at 12Z across IA, with a separate
cluster of elevated convection possible farther northeast in WI. A
downstream split in severe potential may occur as the MCS likely
persists and evolves southeastward. The WI activity may progress and
intensify across Lower MI by afternoon, where deep-layer shear will
be stronger but instability weaker. Scattered damaging winds and
marginal severe hail should be the main hazards. The IA MCS should
progress along the northwest/southeast-oriented MLCAPE gradient
towards the Lower OH Valley. Most CAMs struggle to greatly intensify
this MCS, perhaps owing to warming mid-level temperatures modulating instability. Scattered damaging wind swaths, with some hail risk
along the southwest flank of the MCS, may occur in the morning, but
will most likely peak into the afternoon.

...VA to northern NC...
A similar setup to Friday afternoon is anticipated, but perhaps
shifted slightly farther north. Ample buoyancy is again expected
across the Carolina Coastal Plain into southern VA with a gradient
in MLCAPE shifted northward in the Mid-Atlantic States. Around 20-kt
500-mb westerlies will support weakly organized multicell clusters
as scattered to numerous storms develop through the afternoon.
Sporadic strong gusts producing damaging winds are possible.

..Grams/Wendt.. 07/19/2025

$$

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ACUS01 KWNS 191246
SWODY1
SPC AC 191245

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0745 AM CDT Sat Jul 19 2025

Valid 191300Z - 201200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN/CENTRAL PLAINS...MIDWEST/GREAT LAKES...AND
VIRGINIA/NORTH CAROLINA...

...SUMMARY...
Scattered damaging winds are possible today across parts of the
Midwest/Great Lakes and southern Mid-Atlantic. Scattered large to
very large hail and severe gusts are possible across the
northern/central Plains during the late afternoon and evening.

...Midwest/Great Lakes...
A small thunderstorm cluster ongoing this morning across
southern/eastern IA should continue to track east-southeastward
along an instability gradient across parts of northern MO, IL, and
perhaps IN into at least the early afternoon. With sufficient
organization and evidence of a cold pool, this cluster may pose a
threat for strong to locally damaging winds. Reference Mesoscale
Discussion 1719 for more details. The potential for additional
strong to severe thunderstorms across the Midwest and Great Lakes
regions remains somewhat unclear given rather nebulous/weak forcing
aloft. Stronger westerly mid-level flow associated with upper
troughing over eastern Canada should tend to remain mostly displaced
to the north of the surface warm sector. Still, daytime heating of a
moist low-level airmass will likely encourage the development of
moderate to locally strong instability by early to mid afternoon
away from convective influences.

Somewhat stronger flow aloft and related deep-layer shear should be
present this afternoon across Lower MI. A mix of multicells and
marginal supercells may spread eastward from ongoing activity across
WI, or develop separately over this area while posing a threat for
isolated severe hail and damaging winds. Farther south into the
Midwest/OH Valley, weaker deep-layer shear and the bulk of
convection-allowing model guidance suggests that multicell clusters
should be the main convective mode. One or more of these clusters
will probably persist from the ongoing activity this morning, or
develop this afternoon along its outflow. Scattered severe/damaging
winds will likely be the main threat as these thunderstorms move east-southeastward this afternoon into early evening across much of
the OH Valley/Midwest. This convection should eventually weaken this
evening as it encounters a less unstable airmass across the Lower
Great Lakes and central Appalachians.

...Virginia/North Carolina...
The Mid-Atlantic region will once again reside between upper
troughing to the north over the Northeast/eastern Canada, and a
mid/upper-level anticyclone anchored over the Southeast. The primary
synoptic front remains draped generally east-west along/near the
MD/PA/DE border. A very moist low-level airmass remains in place to
the south of this boundary, with surface dewpoints generally in the
low to mid 70s. A similar convective scenario to yesterday is
forecast again today. Diurnal heating of this moist airmass will
likely encourage moderate to locally strong MLCAPE by early
afternoon, even though mid-level lapse rates are expected to remain
poor. Around 15-25 kt of mid-level westerly flow should enable
thunderstorms that initially develop over the Appalachians/Blue
Ridge to advance eastward towards the lower elevations/coastal
regions of VA/NC this afternoon and early evening. Scattered
damaging winds should be the main threat with loosely organized multicells/clusters. Isolated hail may occur with the stronger cores
as well.

...Northern/Central Plains...
An upper trough/low is expected to persist today over western
Canada. On the southern periphery of this feature, a weak mid-level
shortwave trough should move eastward across the northern
Rockies/High Plains through this evening. Weaker mid-level westerly
flow will remain farther south into the central High Plains. At the
surface, a lee trough will extend southward from eastern MT to
eastern CO. Generally low to mid 60s surface dewpoints should exist
this afternoon along/east of the lee trough, with greater low-level
moisture present near a remnant front/boundary in NE. Isolated
thunderstorms across northeast MT may pose an isolated hail threat
this morning. Current expectations are for scattered thunderstorms
to develop initially over the higher terrain of the northern/central
Rockies this afternoon, with additional development farther east
along the lee trough.

As this convection spreads eastward into a moderately to strongly
unstable airmass across the northern/central High Plains, it should
strengthen. Weak low-level winds are forecast to veer and increase
with height through mid/upper levels, supporting strong deep-layer
shear and the potential for supercells. Scattered large hail will be
possible with any supercells that can persist, with most guidance
indicating a greater concentration of severe thunderstorms across
eastern MT into western ND, and separately across western/central
NE. Given the presence of steep mid-level lapse rates and 40-50+ kt
of deep-layer shear, isolated very large hail appears possible. If
one or more clusters can develop from the initial supercells, then a
greater threat for severe gusts would be realized this evening with
eastward extent across the northern/central Plains. There is low
confidence in this scenario occurring, however.

..Gleason/Bentley.. 07/19/2025

$$

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ACUS01 KWNS 191632
SWODY1
SPC AC 191630

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1130 AM CDT Sat Jul 19 2025

Valid 191630Z - 201200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN/CENTRAL PLAINS...MIDWEST/GREAT LAKES...AND
VIRGINIA/NORTH CAROLINA...

...SUMMARY...
Scattered damaging winds are possible today across parts of the
Midwest/Great Lakes and southern Mid-Atlantic. Scattered large to
very large hail and severe gusts are possible, along with a
potential tornado threat, across the northern/central Plains during
the late afternoon and evening.

...Midwest/Great Lakes...
An ongoing sub-severe MCS continues east-southeast across IL with an
attendant warm advection cluster of thunderstorms downstream over
the lower Wabash Valley. Considerable convective overturning
coupled with convective cloud debris have acted to limit
destabilization thus far across IL into western IN and northward
into the southwest Great Lakes. Have reduced severe probabilities
this outlook update for northern IL into WI due to limited
destabilization, and models converging on limited storm coverage
through the remainder of the day and their depiction of primary
thunderstorm activity tonight occurring farther south/southwest over
IA into central IL towards daybreak.

However, downstream of the ongoing thunderstorm clusters over IL/IN,
gradual heating will probably support some intensification of storms
into the afternoon. Isolated to perhaps scattered damaging winds in
small clusters appear to be the primary severe hazard. Other
thunderstorm development is possible over Lower MI where a
wind-damage threat may materialize with the stronger storms that
develop this afternoon. Later this afternoon but more likely into
tonight, additional storms are forecast to develop on the trailing
outflow with an attendant risk for mainly hail/wind.

...Virginia/North Carolina...
A west-east draped frontal zone resides over southern PA to the
north of this region. However, a very moist low-level airmass
featuring lower to mid 70s dewpoints will continue to
heat/destabilize through mid-late afternoon and promote the
development of moderate buoyancy. Despite weak mid-level lapse
rates, high PW (around 2 inches) will promote water-loaded
downdrafts capable of strong to severe gusts and scattered wind
damage with the more organized cluster(s). Around 15-25 kt of
mid-level westerly flow will favor eastward-moving storm activity.
The severe risk is expected to concentrate during the 20-01 UTC
period as storms move towards central VA and into eastern VA by this
evening.

...Northern/Central Plains...
Water-vapor imagery shows a mid-level impulse moving eastward across
the northwest quarter of MT this morning. This will continue
eastward towards eastern MT and the western Dakotas by early
evening. Weaker mid-level westerly flow will remain farther south
into the central High Plains. At the surface, a lee trough will
extend southward from eastern MT to eastern CO. Generally low to mid
60s surface dewpoints should exist this afternoon along/east of the
lee trough, with upper 60s to lower 70s F dewpoints present near a
remnant front/boundary in NE.

Scattered thunderstorms will likely develop initially over the
higher terrain of the northern/central Rockies this afternoon, with
additional development farther east along the lee trough. As this
convection spreads eastward into a moderately to strongly unstable
airmass across the northern/central High Plains, it should
strengthen. Weak low-level winds are forecast to veer and increase
with height through mid/upper levels, supporting strong deep-layer
shear and the potential for supercells. Scattered large hail will be
possible with any supercells that can persist, with most guidance
indicating a greater concentration of severe thunderstorms across
eastern MT into western ND, and separately across western/central
NE. Given the presence of steep mid-level lapse rates and 40-50+ kt
of deep-layer shear, isolated very large hail appears possible.
Recent model guidance indicates a few supercells may develop across west-central NE late this afternoon into the evening. Some
enlargement of the hodograph during the evening combined with moist
low levels may support a couple hour window for a locally higher
tornado risk compared to within this broader region.

..Smith/Weinman.. 07/19/2025

$$

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ACUS01 KWNS 191955
SWODY1
SPC AC 191954

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0254 PM CDT Sat Jul 19 2025

Valid 192000Z - 201200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE CENTRAL AND NORTHERN HIGH PLAINS INTO THE MIDWEST...AND PARTS OF
VIRGINIA INTO NORTH CAROLINA...

...SUMMARY...
Scattered strong storms with a severe wind/hail threat are likely
this evening across the northern High Plains into the Midwest, with
a couple of tornadoes possible over western Nebraska. A few damaging
gusts also remain possible with storms over Virginia into North
Carolina.

...20Z Update...
Substantial changes have been made to the 20Z Day 1 Convective
Outlook update. First, Slight risk probabilities have been dropped
across portions of the Great Lakes into the OH Valley region. Storms
ongoing over this part of the CONUS have not shown robust severe
potential thus far. Ongoing storms are also overturning the
troposphere during peak heating, casting doubts on adequate airmass modification/destabilization for a renewed organized severe threat. Nonetheless, an isolated damaging gust or brief tornado could occur
with a stronger storm that can become sustained, hence the
maintenance of a Category 1/Marginal Risk.

Wind-driven Slight risk probabilities have been added over portions
of the MO River Valley, joining the Slight risk across the High
Plains and Midwest areas. From eastern NE into northern IL,
thunderstorms are expected to develop along the warm-frontal
low-level boundary this evening given enhanced convergence driven by
a low-level jet. Furthermore, there is some concern that supercells
could congeal into an MCS across central NE and potentially
propagate eastward along this boundary early tonight, fostering a
damaging gust threat.

Otherwise, ongoing multicells over VA into NC will continue through
the afternoon with a damaging gust threat. Supercells and small
bowing segments are also still expected across the central/northern
High Plains this afternoon and evening, accompanied by severe wind
and hail. A couple of tornadoes may accompany any more robust,
sustained supercells over western into central NE with the onset of
low-level jet development this evening.

..Squitieri.. 07/19/2025

.PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Jul 19 2025/

...Midwest/Great Lakes...
An ongoing sub-severe MCS continues east-southeast across IL with an
attendant warm advection cluster of thunderstorms downstream over
the lower Wabash Valley. Considerable convective overturning
coupled with convective cloud debris have acted to limit
destabilization thus far across IL into western IN and northward
into the southwest Great Lakes. Have reduced severe probabilities
this outlook update for northern IL into WI due to limited
destabilization, and models converging on limited storm coverage
through the remainder of the day and their depiction of primary
thunderstorm activity tonight occurring farther south/southwest over
IA into central IL towards daybreak.

However, downstream of the ongoing thunderstorm clusters over IL/IN,
gradual heating will probably support some intensification of storms
into the afternoon. Isolated to perhaps scattered damaging winds in
small clusters appear to be the primary severe hazard. Other
thunderstorm development is possible over Lower MI where a
wind-damage threat may materialize with the stronger storms that
develop this afternoon. Later this afternoon but more likely into
tonight, additional storms are forecast to develop on the trailing
outflow with an attendant risk for mainly hail/wind.

...Virginia/North Carolina...
A west-east draped frontal zone resides over southern PA to the
north of this region. However, a very moist low-level airmass
featuring lower to mid 70s dewpoints will continue to
heat/destabilize through mid-late afternoon and promote the
development of moderate buoyancy. Despite weak mid-level lapse
rates, high PW (around 2 inches) will promote water-loaded
downdrafts capable of strong to severe gusts and scattered wind
damage with the more organized cluster(s). Around 15-25 kt of
mid-level westerly flow will favor eastward-moving storm activity.
The severe risk is expected to concentrate during the 20-01 UTC
period as storms move towards central VA and into eastern VA by this
evening.

...Northern/Central Plains...
Water-vapor imagery shows a mid-level impulse moving eastward across
the northwest quarter of MT this morning. This will continue
eastward towards eastern MT and the western Dakotas by early
evening. Weaker mid-level westerly flow will remain farther south
into the central High Plains. At the surface, a lee trough will
extend southward from eastern MT to eastern CO. Generally low to mid
60s surface dewpoints should exist this afternoon along/east of the
lee trough, with upper 60s to lower 70s F dewpoints present near a
remnant front/boundary in NE.

Scattered thunderstorms will likely develop initially over the
higher terrain of the northern/central Rockies this afternoon, with
additional development farther east along the lee trough. As this
convection spreads eastward into a moderately to strongly unstable
airmass across the northern/central High Plains, it should
strengthen. Weak low-level winds are forecast to veer and increase
with height through mid/upper levels, supporting strong deep-layer
shear and the potential for supercells. Scattered large hail will be
possible with any supercells that can persist, with most guidance
indicating a greater concentration of severe thunderstorms across
eastern MT into western ND, and separately across western/central
NE. Given the presence of steep mid-level lapse rates and 40-50+ kt
of deep-layer shear, isolated very large hail appears possible.
Recent model guidance indicates a few supercells may develop across west-central NE late this afternoon into the evening. Some
enlargement of the hodograph during the evening combined with moist
low levels may support a couple hour window for a locally higher
tornado risk compared to within this broader region.

$$

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ACUS01 KWNS 200102
SWODY1
SPC AC 200100

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0800 PM CDT Sat Jul 19 2025

Valid 200100Z - 201200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE
NORTHERN AND CENTRAL HIGH PLAINS INTO THE MIDWEST...

...SUMMARY...
Strong to severe storms remain possible this evening into late
tonight from parts of the central and northern High Plains into
parts of the Corn Belt.

...Central Plains into parts of IA/IL...
Strong to extreme buoyancy and favorable deep-layer shear (as noted
on the 00Z OAX sounding) remain in place across much of NE into
western/central IA. Ongoing supercells will continue to pose a
threat for large hail, localized severe gusts, and possibly a
tornado or two through much of the evening.

A nocturnally strengthening low-level jet may support an increase in
storm coverage later tonight from eastern NE into parts of IA.
Potential for organized MCS development remains uncertain, but any
substantial storm clustering could result in a damaging wind and
isolated hail threat spreading eastward overnight, potentially
reaching parts of northern IL before the end of the period.

...Northern High Plains...
Widely scattered supercells may persist through much of the evening
across the northern High Plains, within an environment characterized
by moderate to strong instability and favorable deep-layer shear (as
depicted in the 00Z GGW and UNR soundings). Large hail and localized
severe gusts may accompany the strongest storms. Some modest upscale
growth is possible late tonight from eastern MT into ND, in
association with a mid/upper-level shortwave trough moving across
southern SK. While an isolated severe threat could continue across
this region into the overnight hours, decreasing instability and
increasing CINH should eventually result in a gradual weakening
trend.

...Mid Atlantic...
A few strong storms are ongoing this evening from eastern VA into
NC. Localized wind damage remains possible with the strongest
remaining storms, though the threat should eventually diminish as
storms weaken with time and/or move offshore.

...WI/Lower MI vicinity...
Some increase in storm coverage remains possible this evening across
parts of WI and lower MI, in the vicinity of a cold front. Modest
buoyancy and moderate deep-layer shear could support a strong storm
or two capable of locally damaging wind.

..Dean.. 07/20/2025

$$

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ACUS01 KWNS 200601
SWODY1
SPC AC 200559

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1259 AM CDT Sun Jul 20 2025

Valid 201200Z - 211200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE NORTHEAST...MIDWEST...OHIO VALLEY...AND NORTHERN PLAINS...

...SUMMARY...
Strong to severe storms appear most likely later today into this
evening across parts of the Northeast, Midwest and Ohio Valley, and
northern Plains.

...Northeast...
A deep upper-level trough over parts of Quebec and Ontario will dig southeastward through the day today. As this occurs, cooling aloft
and increasing mid/upper-level flow is expected from northern parts
of the Mid Atlantic into New England. Midlevel lapse rates will
generally remain weak, but diurnal heating of a moist airmass will
result in MLCAPE increasing to 1000-1500 J/kg along/ahead of a cold
front.

Scattered storm development is expected along/ahead of the front
this afternoon, with effective shear of 35-45 kt sufficient for
storm organization. A few supercells will be possible initially,
with a threat for locally damaging wind, isolated hail, and possibly
a tornado. With time, some storm clustering is possible, which could
lead to locally more concentrated areas of wind damage. Some severe
threat could linger into the early evening for near-coastal areas,
before storms move offshore.

...Parts of the Mid MS and OH Valleys...
Despite warm temperatures aloft, heating of a very moist airmass
will support MLCAPE increasing into the 2000-3000 J/kg range this
afternoon across parts of the mid MS and OH Valleys, near/south of a
remnant surface boundary and any convective outflows. Modestly
enhanced west-northwesterly mid/upper flow will conditionally
support organized storm potential, though evolution of storms
through the day and evening across the region remains somewhat
uncertain.

An MCS (or its remnant) may move from parts of IL/IN toward parts of
the upper OH Valley through the day. Some reintensification of this
system, and/or development along its trailing outflow, will be
possible during the afternoon, with steepening low-level lapse rates
and large PW supporting localized downbursts and damaging outflow
winds. Additional development will be possible farther west near the outflow-influenced surface boundary, which could result in
development of organized cells/clusters capable of damaging wind.
Deep-layer shear will be marginally supportive of supercells, and
some threat for hail and a tornado cannot be ruled out with any
sustained supercells. Some severe threat could linger into tonight,
as modest low-level warm advection helps to regenerate storms near
and north of the effective surface boundary.

...Northern/central Plains...
A mid/upper-level trough will remain in place over the Northwest and
northern Rockies today. A surface trough will extend from eastern MT
into the central High Plains this afternoon. East of the surface
trough, a surface boundary initially draped across parts of NE/KS
will attempt to lift north as a warm front, in the wake of early
morning convection.

Details regarding storm development and evolution remain rather
uncertain across the region, but most guidance suggests at least
isolated storm development will be possible near the surface trough
and near/north of the effective warm front sometime this afternoon
or evening. Effective shear of 40+ kt will support initial supercell development, with a threat of hail, isolated severe gusts, and
possibly a tornado. Outflow consolidation could lead to some
clustering and upscale growth, which would tend to move
southeastward with a continued threat of at least localized severe
gusts and isolated hail into tonight.

..Dean/Wendt.. 07/20/2025

$$

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ACUS01 KWNS 201230
SWODY1
SPC AC 201228

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0728 AM CDT Sun Jul 20 2025

Valid 201300Z - 211200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE NORTHEAST...MIDWEST...OHIO VALLEY...AND NORTHERN PLAINS...

...SUMMARY...
Strong to severe storms appear most likely later today into this
evening across parts of the Northeast, Midwest and Ohio Valley, and
northern Plains.

...Synopsis...
A mid-level trough will amplify across the Northeast today with
increasing mid-level flow ahead of an approaching jet streak. A
low-amplitude ridge will build somewhat across the Upper Midwest.
Farther west, mid-level flow will strengthen across the northern
Rockies into the northern Plains as a trough amplifies on the
Pacific Northwest coast.

As of 12Z, an elongated frontal zone exists from the Northeast to
the Ohio Valley/southern Great Lakes and into the northern Plains.
Ongoing thunderstorms are present across the eastern Great Lakes,
the Midwest, and the northern Plains. This is correlated with the
stronger ascent and the areas with the greatest severe weather
potential today.

...Northeast...
Weak to moderate instability is forecast to develop across the
Northeast today as temperatures warm into the 80s with dewpoints in
the upper 60s, and as mid-level temperatures gradually cool through
the day. As the cold front advances east into this uncapped airmass,
scattered thunderstorms should develop. Shear of 30 to 35 knots and
relatively long/straight hodographs will support the potential for
supercells. Weak mid-level lapse rates will be the primary limiting
factor for large hail, but the overall favorable shear with strong
venting aloft and potential supercells may support some isolated
large hail.

Damaging wind gusts will be the primary threat, both from initial
cells and also from any clusters which develop. Any stronger
clusters with bowing segments could support a better organized
damaging wind swath. The greatest wind damage threat will likely
exist from western Massachusetts to far southern Maine.

...Ohio Valley...
A large mass of thunderstorms continues east across eastern Iowa and
northern Illinois this morning. Heating is anticipated south and
east of this activity which should result in an increasing severe
weather threat by late morning to early afternoon. It remains
unclear whether the afternoon severe threat may materialize out of
ongoing thunderstorm activity, or from additional storm development
along the front or the outflow boundary associated with these
storms. Nonetheless, 1000 to 1500 J/kg MLCAPE and effective shear of
35 to 40 knots will support an organized severe weather threat
including the potential for supercells. Despite the supercell mode,
the hail threat should remain minimal given the weak mid-level lapse
rates and warm mid-level temperatures with high freezing levels.
Damaging wind gusts will be the primary threat from these storms
with the greatest threat from central Indiana to southwest Ohio and
northern Kentucky.

...Northern Plains...
Weak lee troughing is forecast in the western Nebraska vicinity
today as moderate mid-level flow overspreads the northern Plains. A
dryline will extend southward from this surface low into the central
High Plains. Isolated storms are possible along this boundary this afternoon/evening. Moderate destabilization is forecast across
central South Dakota and vicinity as low-level moisture is advected
westward to the north of the surface low.

Diurnal thunderstorm activity is forecast to be relatively isolated
along the dryline with perhaps slightly greater coverage across
eastern Minnesota amid cooler temperatures aloft. However, the
ongoing cluster of storms across North Dakota is forecast to linger
as isentropic ascent is maintained through the day. Eventual upscale
growth and a southeastward movement along the instability gradient
is anticipated. RAP forecast soundings show an environment favorable
for large hail initially with any supercells which develop. However,
the severe wind threat may increase by this evening as storms
congeal into a MCS with potential linear, bowing segments.

..Bentley/Gleason.. 07/20/2025

$$

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ACUS01 KWNS 201632
SWODY1
SPC AC 201630

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1130 AM CDT Sun Jul 20 2025

Valid 201630Z - 211200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
THE NORTHERN AND CENTRAL PLAINS...OHIO VALLEY...AND PARTS OF THE
NORTHEAST...

...SUMMARY...
Severe thunderstorms appear most likely this afternoon into this
evening across parts of the Northeast, portions of the northern and
central Plains, and perhaps the Ohio Valley.

...Synopsis...
A mid-level trough will amplify across the Northeast today with
increasing mid-level flow ahead of an approaching jet streak. A
low-amplitude ridge will build somewhat across the Upper Midwest.
Farther west, mid-level flow will strengthen across the northern
Rockies into the northern Plains as a trough amplifies on the
Pacific Northwest coast.

...Northeast...
Weak to moderate instability is forecast to develop across the
Northeast through mid afternoon as the airmass continues to
destabilize. Midday surface analysis indicates temperatures are
warming into the 80s with dewpoints in the upper 60s to lower 70s.
As the cold front advances east into this uncapped airmass,
scattered thunderstorms should develop. Shear of 30 to 35 knots and
relatively long/straight hodographs will support the potential for
supercells. Weak mid-level lapse rates will be the primary limiting
factor for large hail, but the overall favorable shear with strong
venting aloft and potential supercells may support some isolated
large hail.

Damaging wind gusts will be the primary threat, both from initial
cells and also from any clusters which develop. Any stronger
clusters with bowing segments could support a better organized
damaging wind swath. The greatest wind damage threat will likely
exist from western Massachusetts to far southern Maine.

...Southeast MT into the Dakotas and Central Plains...
Lee troughing is forecast to extend southward from eastern MT into
the central High Plains near and south of the westerlies confined to
the northern tier of states. Elevated weak thunderstorm activity
along the ND/SD border may continue but considerable uncertainty
exists whether these storms will intensify and pose a severe risk
this afternoon. Meanwhile, farther west, moist low levels arc from
southeast MT southeastward through west-central SD and south into
NE/northwest KS. Strong heating will contribute to a moderate to
very unstable airmass from the central Plains states into eastern
MT. Easterly low-level flow beneath 30-40 kt 500 mb flow in
southeast MT will support organized storms, including supercell
potential. Isolated to scattered storms are forecast to develop and
spread east into the Dakotas. Other isolated to widely scattered
storms are possible from SD southward into NE/CO/KS border vicinity
late this afternoon into the evening.

Large to very large hail will be possible with any supercells that
develop within this general region. However, the severe wind threat
may increase by this evening and become the main threat as storms
congeal into one or more clusters or MCS.

...Ohio Valley...
Visible-satellite/radar composite shows an elongated area of showers/thunderstorms from northern MO east into western OH in
conjunction with an MCV moving east from IL into IN. Additional
storm development along the composite front/trailing outflow
boundary is expected, but timing of this storm activity remains
unclear. Nonetheless, differential heating along the baroclinic
zone will yield 2000 to 3000 J/kg MLCAPE amidst moderate effective
shear (25-35 kt). A few clusters are forecast to eventually evolve
later this afternoon into the evening with the stronger storms
capable primarily of a wind-damage threat.

..Smith/Halbert.. 07/20/2025

$$

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ACUS01 KWNS 201941
SWODY1
SPC AC 201939

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0239 PM CDT Sun Jul 20 2025

Valid 202000Z - 211200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
THE CENTRAL INTO NORTHERN PLAINS...PARTS OF THE OHIO VALLEY...AND
PARTS OF THE NORTHEAST...

...SUMMARY...
Severe thunderstorms appear most likely this afternoon into this
evening across parts of the Northeast, portions of the northern and
central Plains, and perhaps the Ohio Valley.

...20Z Update...
The primary change made to the Day 1 outlook was to add 5 percent
tornado probabilities across south-central SD into north-central NE.
Here, a cluster of supercells is expected to develop along a diffuse warm-frontal boundary, where directional low-level shear will be
present. Up to 200 m2/s2 effective SRH in this region may support
the development of a tornado in addition to severe winds and very
large hail, given 2500-4000 J/kg MLCAPE by evening.

Consideration was also given to remove Slight risk and 2 percent
tornado probabilities over the OH Valley given remnant cloud cover
and overall lack of upper support to foster an organized severe
threat. However, on the immediate southern periphery of this cloud
deck resides an axis of overlapping 2000+ MLCAPE and 30+ kts of
effective bulk shear. Should storms manage to develop, especially
before nocturnal cooling commences, a conditional risk for scattered
damaging gusts or a brief tornado would exist, so 15 percent severe
wind/2 percent tornado probabilities have been maintained.

Otherwise, the previous forecast (see below) remains on track.

..Squitieri.. 07/20/2025

.PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Jul 20 2025/

...Synopsis...
A mid-level trough will amplify across the Northeast today with
increasing mid-level flow ahead of an approaching jet streak. A
low-amplitude ridge will build somewhat across the Upper Midwest.
Farther west, mid-level flow will strengthen across the northern
Rockies into the northern Plains as a trough amplifies on the
Pacific Northwest coast.

...Northeast...
Weak to moderate instability is forecast to develop across the
Northeast through mid afternoon as the airmass continues to
destabilize. Midday surface analysis indicates temperatures are
warming into the 80s with dewpoints in the upper 60s to lower 70s.
As the cold front advances east into this uncapped airmass,
scattered thunderstorms should develop. Shear of 30 to 35 knots and
relatively long/straight hodographs will support the potential for
supercells. Weak mid-level lapse rates will be the primary limiting
factor for large hail, but the overall favorable shear with strong
venting aloft and potential supercells may support some isolated
large hail.

Damaging wind gusts will be the primary threat, both from initial
cells and also from any clusters which develop. Any stronger
clusters with bowing segments could support a better organized
damaging wind swath. The greatest wind damage threat will likely
exist from western Massachusetts to far southern Maine.

...Southeast MT into the Dakotas and Central Plains...
Lee troughing is forecast to extend southward from eastern MT into
the central High Plains near and south of the westerlies confined to
the northern tier of states. Elevated weak thunderstorm activity
along the ND/SD border may continue but considerable uncertainty
exists whether these storms will intensify and pose a severe risk
this afternoon. Meanwhile, farther west, moist low levels arc from
southeast MT southeastward through west-central SD and south into
NE/northwest KS. Strong heating will contribute to a moderate to
very unstable airmass from the central Plains states into eastern
MT. Easterly low-level flow beneath 30-40 kt 500 mb flow in
southeast MT will support organized storms, including supercell
potential. Isolated to scattered storms are forecast to develop and
spread east into the Dakotas. Other isolated to widely scattered
storms are possible from SD southward into NE/CO/KS border vicinity
late this afternoon into the evening.

Large to very large hail will be possible with any supercells that
develop within this general region. However, the severe wind threat
may increase by this evening and become the main threat as storms
congeal into one or more clusters or MCS.

...Ohio Valley...
Visible-satellite/radar composite shows an elongated area of showers/thunderstorms from northern MO east into western OH in
conjunction with an MCV moving east from IL into IN. Additional
storm development along the composite front/trailing outflow
boundary is expected, but timing of this storm activity remains
unclear. Nonetheless, differential heating along the baroclinic
zone will yield 2000 to 3000 J/kg MLCAPE amidst moderate effective
shear (25-35 kt). A few clusters are forecast to eventually evolve
later this afternoon into the evening with the stronger storms
capable primarily of a wind-damage threat.

$$

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ACUS01 KWNS 210106
SWODY1
SPC AC 210104

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0804 PM CDT Sun Jul 20 2025

Valid 210100Z - 211200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF THE
NORTHERN/CENTRAL PLAINS...PARTS OF THE LOWER/MIDDLE OHIO VALLEY...

...SUMMARY...
Widely scattered severe storms remain possible in parts of the
northern/central Plains. Additional strong to severe storms are
possible in parts of the lower/middle Ohio Valley.

...Ohio Valley...
An MCV moving into Illinois is continuing to promote convection
along a stationary boundary. Though deep-layer shear is modest,
strong buoyancy is still in place. A couple of more organized
clusters may produce wind damage as they move southeastward this
evening. A brief tornado near the boundary could also occur.

...Northern/central Plains...
Several supercells are ongoing in parts of eastern Montana into
southwest South Dakota. Steep mid-level lapse rates and strong shear
will continue to promote storms capable of large/very-large hail and
severe wind gusts. Farther south, isolated but intense supercells
have persisted in south-central South Dakota into north-central
Nebraska. Large/very-large hail and severe gusts are the main
concerns, but low-level shear will increase modestly this evening
and a tornado will remain possible.

...Kansas/Missouri...
As the low-level jet increases this evening, warm advection is
expected to initiate convection in northern Missouri and perhaps
northeast Kansas. Given around 3000+ J/kg MLCAPE, the stronger
storms may produce isolated strong/damaging winds later this
evening.

..Wendt.. 07/21/2025

$$

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ACUS01 KWNS 210553
SWODY1
SPC AC 210552

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1252 AM CDT Mon Jul 21 2025

Valid 211200Z - 221200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF CENTRAL
AND EASTERN MONTANA...

...SUMMARY...
Severe thunderstorms capable of producing severe wind gusts, large
hail, and perhaps a tornado or two are expected across parts of the
northern Great Plains. Additional isolated strong to severe storms
are possible in the central Plains.

...Synopsis...
Modest amplification of an upper-level ridge is expected across the
Plains into the Upper Midwest today. In the Northwest, the
upper-level trough will take on a more neutral tilt before
progressing eastward by Tuesday morning. At the surface, modest lee
troughing will be in place within the northern/central High Plains
regions. An outflow boundary is likely to be situated somewhere in
the North Dakota/South Dakota border vicinity. Farther east into
Minnesota, a warm front like feature will arc southeastward into the
lower Ohio Valley. Strong to extreme buoyancy is forecast to develop
within parts of the northern/central Plains.

...Montana into western North Dakota...
The highest confidence in the development of severe storms is within
the terrain of central Montana. Additional storms may develop in the
vicinity of the Big Horns and move into southeast Montana. Mid-level
heights will be rising through the morning/afternoon so initiation
could be somewhat delayed. Subtle mid-level height falls will occur
during the evening, however. With a belt of strong mid-level winds
across the region, initial storms should be supercellular. Large
hail and severe wind gusts will be the initial hazards. With storms
developing in somewhat drier air, it is possible they will be
outflow dominant and not maintain their cellular mode as they move
northeast into greater moisture. The environment will be
conditionally favorable for 2+ inch hail, but the spatial extent of
this threat is not certain. Severe wind gusts will likely become
more common later in the evening as activity grows upscale.

...Dakotas into Minnesota/Mid-Missouri Valley...
Two clusters of convection are ongoing in the Dakotas. Based on
current surface observations, this activity is expected to generally
move eastward along the North Dakota/South Dakota border. What
occurs with the outflow from this activity into this afternoon will
play a role in the severe potential within parts of the Dakotas.
Strong to extreme buoyancy will be present south of the outflow.
Forcing for ascent will be weak. Storm development will depend on
the timing of the early morning convection and subsequent
heating/mesoscale lift during the afternoon. A weak surface low in
western South Dakota may lead to some locally enhanced convergence
along the outflow and trigger storms. This scenario is also not
certain.

Effective shear of 40-45 kts and MLCAPE likely above 4000 J/kg will
support intense, organized storms. Initial storms would be capable
large hail, severe winds, and perhaps a tornado or two. Storms that
do develop would eventually grow upscale and potentially produce a
swatch of severe winds. Model guidance varies on the timing/location
of this activity. There is some potential for a cluster/MCS to
propagate along the warm front feature into central Minnesota. Other
solutions show the MCS moving into the greater buoyancy toward the
Mid-Missouri Valley. Given some capping can be expected, storms may
not develop at all. The marginal risk has been expanded to account
for these possibilities, but confidence remains too low for a
categorical upgrade at this time.

...Central High Plains...
Strong heating near the surface trough should promote isolated to
widely scattered storms from the Palmer Divide into the Nebraska
Panhandle. Effective shear of 25-30 kts (generally weaker with
southern extent) will allow for marginally organized storms. Severe
wind gusts are the main concern as storms develop in the drier air.
Some potential for large hail may also exist if storms can persist
into greater moisture to the east.

..Wendt/Dean.. 07/21/2025

$$

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ACUS01 KWNS 211234
SWODY1
SPC AC 211232

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0732 AM CDT Mon Jul 21 2025

Valid 211300Z - 221200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN PLAINS...

...SUMMARY...
Severe thunderstorms capable of producing large hail, severe gusts,
and perhaps a tornado or two will be possible today and tonight
across parts of the northern Plains. Additional isolated strong to
severe storms may occur across portions of the central Plains.

...Northern Plains into the Upper Midwest...
A long-lived and compact MCS has advanced into parts of west-central
MN this morning. This convection is on the northern periphery of
meaningful low-level moisture and related instability. It should
generally weaken over the next few hours while it tracks
southeastward over southern MN as a low-level jet gradually lessens.
But in the short term, it may still be capable of producing
occasional strong to severe wind gusts. Behind this activity, a
moist and rather unstable airmass will exist across the northern
Plains along and south of a convectively reinforced front that
should become oriented generally east-west along the ND/SD border by
late this afternoon. Large-scale ascent across the northern Plains
will likely be weak for much of the day, as upper ridging remains
prominent over the central CONUS.

Even so, there are indications that a weak mid-level perturbation
emanating from upper troughing over the Pacific Northwest should
overspread the northern Rockies and adjacent High Plains of
central/eastern MT by mid/late afternoon as ample daytime heating of
a slowly moistening low-level airmass occurs. A belt of enhanced west-southwesterly mid-level flow will accompany this feature,
supporting ample veering/strengthening of the wind profile with
height through mid/upper levels. Related strong deep-layer shear of
40-50+ kt will easily support supercells with initial development
off the Bighorns given the presence of at least moderate instability
across the High Plains. Large hail will be possible with these
supercells this afternoon, followed by an increasing severe wind
threat with time this evening/overnight into parts of the Dakotas as
convection potentially grows upscale, and where ample MUCAPE and
strong deep-layer shear will be present along/north of the surface
boundary. The development of elevated supercells also appears
possible across parts of the Dakotas late tonight as a low-level jet
gradually strengthens, with a related threat for at least isolated
severe hail if they occur.

...Central Plains...
Much of the central Plains will remain capped today, as the upper
ridge and warm temperatures aloft exert their influence. A surface
trough is expected to extend southward across the central High
Plains this afternoon, and a remnant MCV related to earlier
convection should move eastward along/near the NE/KS border. Both of
these features may aid in at least isolated thunderstorm development
this afternoon, in the presence of moderate to strong instability
amid modest deep-layer shear. Isolated severe hail and wind gusts
may occur with any of the more robust cores that can develop and be
maintained in an otherwise weak forcing regime. The Marginal Risk
has been expanded southward a little to include more of northern KS
and southeast NE, where strong to severe convection may develop
later today in close proximity to the MCV.

...Tennessee Valley into the Southeast...
A weak MCV related to ongoing convection across MO and southern IL
this morning will track southeastward across the TN Valley and
vicinity through this afternoon. Modest west-northwesterly flow
should be in place today across parts of the OH/TN Valleys into the
Southeast. This may support loosely organized multicells and pulse thunderstorms today, as mostly sunny conditions aid in the
development of moderate to locally strong instability this
afternoon. While deep-layer shear is forecast to remain weak, some
of this convection may still be capable of producing strong to
locally damaging winds. Parts of these regions may be considered for
inclusion in a Marginal Risk in a later outlook update, pending
additional observational/model trends.

..Gleason/Bentley.. 07/21/2025

$$

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ACUS01 KWNS 211633
SWODY1
SPC AC 211632

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1132 AM CDT Mon Jul 21 2025

Valid 211630Z - 221200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN PLAINS...

...SUMMARY...
Severe thunderstorms capable of producing large hail, severe gusts,
and perhaps a tornado or two will be possible late this afternoon
into tonight across parts of the northern Plains.

...Northern Plains into the Upper Midwest...
Water-vapor imagery shows a mid-level trough progressing eastward
across the Pacific Northwest towards the northern Rockies. A lead
mid-level vorticity max rotating through the base of the trough is
forecast to pivot east-northeastward from north-central ID into MT
by the early evening. In the low levels, a stationary frontal zone
extends from near the NE/SD border west-northwestward to near the
ID/WY/MT border with an easterly component to the low-level flow
being maintained across eastern into central portions of MT.

A moisture plume protrudes northwestward along and north of this
boundary with a reservoir of 70s F dewpoints over NE to lower 60s in
southeast MT (850-mb dewpoints around 16 deg C per objective
analysis). A notable capping inversion will likely inhibit storm
development until mid afternoon and the initial storm activity will
likely focus near higher terrain and over southern MT. Steep
mid-level lapse rates and 30-45 kt southwesterly 500-mb flow will
support supercells with large to very large hail accompanying these
storms from near the Black Hills into southern MT. A tornado risk
may develop where locally backed flow in the presence of smaller temperature-dewpoint spreads could evolve near the boundary.
Upscale growth into one or more clusters or an MCS seems plausible
this evening into the overnight as storms move/develop east into the
Dakotas.

...Central Plains...
No change was made to the previous forecast for the Central Plains
region. Much of the central Plains will remain capped today, as the
upper ridge and warm temperatures aloft exert their influence. A
surface trough is expected to extend southward across the central
High Plains this afternoon, and a remnant MCV related to earlier
convection should move eastward along/near the NE/KS border. Both of
these features may aid in at least isolated thunderstorm development
this afternoon, in the presence of moderate to strong instability
amid modest deep-layer shear. Isolated severe hail and wind gusts
may occur with any of the more robust cores that can develop and be
maintained in an otherwise weak forcing regime.

...Tennessee Valley into the Southeast...
Midday visible-satellite imagery shows an agitated cumulus field
from southern GA northwestward into the southern Appalachians and
Cumberland Plateau. 12 UTC raobs from Jacksonville, Atlanta, and
Charleston showed PW in excess of 2 inches, signifying a very moist,
deep troposphere. Surface temperatures will continue to warm into
the 90s F, thereby steepening 0-2 km lapse rates. As storms
develop, some of the stronger water-loaded downdrafts may yield a
threat for localized 50-65 mph gusts and pockets of wind damage.
This activity will likely diminish by the evening.

..Smith/Halbert.. 07/21/2025

$$

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ACUS01 KWNS 211957
SWODY1
SPC AC 211955

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0255 PM CDT Mon Jul 21 2025

Valid 212000Z - 221200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN PLAINS...

...SUMMARY...
Severe thunderstorms capable of producing large hail, severe gusts,
and perhaps a tornado or two will be possible late this afternoon
into tonight across parts of the northern Plains.

...20Z Update...
The previous forecast remains on track, and only minor adjustments
were made with this update. In the northern Plains, the Slight risk
was expanded eastward in portions of ND, driven by 15-percent wind probabilities. The latest model guidance is in relatively good
agreement, depicting an eastward-moving cluster of storms through
the early morning hours -- aided by a strengthening low-level jet
and convectively augmented midlevel impulse.

Farther south, the Marginal risk was expanded slightly southward
across central KS. Here, continued diurnal heating/destabilization
amid rich boundary-layer moisture and steep lapse rates will favor
severe wind gusts with any storm clusters that evolve through this
evening.

..Weinman.. 07/21/2025

.PREV DISCUSSION... /ISSUED 1132 AM CDT Mon Jul 21 2025/

...Northern Plains into the Upper Midwest...
Water-vapor imagery shows a mid-level trough progressing eastward
across the Pacific Northwest towards the northern Rockies. A lead
mid-level vorticity max rotating through the base of the trough is
forecast to pivot east-northeastward from north-central ID into MT
by the early evening. In the low levels, a stationary frontal zone
extends from near the NE/SD border west-northwestward to near the
ID/WY/MT border with an easterly component to the low-level flow
being maintained across eastern into central portions of MT.

A moisture plume protrudes northwestward along and north of this
boundary with a reservoir of 70s F dewpoints over NE to lower 60s in
southeast MT (850-mb dewpoints around 16 deg C per objective
analysis). A notable capping inversion will likely inhibit storm
development until mid afternoon and the initial storm activity will
likely focus near higher terrain and over southern MT. Steep
mid-level lapse rates and 30-45 kt southwesterly 500-mb flow will
support supercells with large to very large hail accompanying these
storms from near the Black Hills into southern MT. A tornado risk
may develop where locally backed flow in the presence of smaller temperature-dewpoint spreads could evolve near the boundary.
Upscale growth into one or more clusters or an MCS seems plausible
this evening into the overnight as storms move/develop east into the
Dakotas.

...Central Plains...
No change was made to the previous forecast for the Central Plains
region. Much of the central Plains will remain capped today, as the
upper ridge and warm temperatures aloft exert their influence. A
surface trough is expected to extend southward across the central
High Plains this afternoon, and a remnant MCV related to earlier
convection should move eastward along/near the NE/KS border. Both of
these features may aid in at least isolated thunderstorm development
this afternoon, in the presence of moderate to strong instability
amid modest deep-layer shear. Isolated severe hail and wind gusts
may occur with any of the more robust cores that can develop and be
maintained in an otherwise weak forcing regime.

...Tennessee Valley into the Southeast...
Midday visible-satellite imagery shows an agitated cumulus field
from southern GA northwestward into the southern Appalachians and
Cumberland Plateau. 12 UTC raobs from Jacksonville, Atlanta, and
Charleston showed PW in excess of 2 inches, signifying a very moist,
deep troposphere. Surface temperatures will continue to warm into
the 90s F, thereby steepening 0-2 km lapse rates. As storms
develop, some of the stronger water-loaded downdrafts may yield a
threat for localized 50-65 mph gusts and pockets of wind damage.
This activity will likely diminish by the evening.

$$

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ACUS01 KWNS 220106
SWODY1
SPC AC 220104

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0804 PM CDT Mon Jul 21 2025

Valid 220100Z - 221200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE
NORTHERN PLAINS AND ALSO A SMALL PART OF SOUTH-CENTRAL KS...

...SUMMARY...
Severe thunderstorms remain possible into late tonight across parts
of the northern Plains, and also through the evening across parts of south-central Kansas.

...Parts of MT into the Dakotas and northwest MN...
Multiple clusters of strong to severe storms are ongoing this
evening from central/southeast MT into western SD. The downstream
environment is moderately to strongly unstable and favorably
sheared, and these storm clusters will continue to pose a threat of
hail and strong to severe gusts in the short term as they move east-northeastward. See MCD 1748 for more information regarding the
short-term threat in this area.

With time, a modestly increasing low-level jet may support upscale
growth into an MCS somewhere from northwest SD into ND, though
short-term guidance continues to vary regarding the details. Rather
strong CINH across northwest SD into southwest ND may tend to delay
any organized upscale growth until late tonight, though increasing
low-level warm advection and steep midlevel lapse rates could help
to sustain ongoing convection as it moves through this region. Any
organized cluster or larger MCS that develops could pose a
damaging-wind threat through the overnight hours into parts of
eastern ND, northeast SD, and potentially northwest MN.

...Central/southern Plains...
A large cluster of storms across north-central KS may tend to
propagate south-southeastward through the evening, within a moderate
to strongly unstable environment. Decreasing shear with southward
extent and the influence of convective outflow across both northeast
and southwest KS will eventually result in a weakening trend, but
some threat for strong to severe gusts and hail may persist with
this cluster through the evening. See MCD 1749 for more information.

Farther south, high-based convection may persist through dusk from
the TX/OK Panhandles into southwest TX, with a threat of localized
strong to severe gusts.

..Dean.. 07/22/2025

$$

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ACUS01 KWNS 220602
SWODY1
SPC AC 220600

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Tue Jul 22 2025

Valid 221200Z - 231200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE
NORTHERN PLAINS INTO NORTHERN MN...

...SUMMARY...
Scattered severe thunderstorms are expected over parts of the
northern Plains into the upper Mississippi Valley later today into
tonight.

...Northern Plains into the Upper Great Lakes region...
An active severe-weather day still appears possible across parts of
the northern Plains into the upper MS Valley/Great Lakes, though
considerable uncertainty remains regarding the evolution of storms
through the day.

One or more storm clusters and possibly a remnant MCS may be ongoing
at the start of the period somewhere from eastern ND into northern
MN, though guidance varies regarding the details. Any organized
cluster or MCS that is ongoing may pose a threat for at least
localized damaging gusts into parts of northern MN through the
morning, along with some hail potential with any semi-discrete
cells.

A surface low is forecast to move eastward across SD through the
day, downstream of a positively tilted upper-level trough over the
northern Rockies. An outflow-influenced surface boundary will extend
northeast from the low into parts of the eastern Dakotas and
northern MN, though its placement is somewhat uncertain by
afternoon. Strong instability will develop by afternoon near and
south of the boundary, and also within a region of moist
east/northeasterly flow north and northwest of the surface low. The
strongest mid/upper-level flow will be north of the boundary, but
backed low-level flow near the boundary will result in favorable
deep-layer shear for organized convection.

There will be some potential for supercell development near the
surface low and northeastward along the boundary during the
afternoon and evening, though coverage is uncertain due to rather
subtle large-scale forcing. Any sustained supercells within this
environment could pose some tornado threat, in addition to potential
for large to very large hail and localized severe gusts. Greater
tornado probabilities may be needed if confidence increases in
supercell development during the afternoon and evening.

Farther west, widely scattered storm development is again expected
across parts of MT and northern WY, initially within the
post-frontal environment. Moderate instability and favorable
deep-layer shear will support a mixture of cells and clusters with
hail and severe-wind potential as they move east-northeastward. With
time, upscale growth will be possible, either from convection moving
out of the northern High Plains, or from storms developing farther
east near the surface boundary. This could result in potential for a
swath of damaging winds during the evening and overnight, though the
favored corridor for this potential remains uncertain at this time.


...IA into southern MN/WI...
An MCV generated by the extensive MCC over the central Plains Monday
evening is forecast by most 00Z guidance to move northeastward
toward IA and southern MN/WI through the period. The extent of flow
enhancement and storm development associated with this feature is
uncertain, but it is forecast to track across a moist and unstable
environment during the afternoon and evening, and could aid in the
development of a few strong storms. Locally damaging gusts will be
possible, and a tornado cannot be ruled out if the MCV remains
somewhat vigorous.

...Parts of the Southeast...
A weak cold front will move across parts of the Carolinas and
Georgia today into this evening. Very rich moisture (PWs above 2
inches) will support scattered to numerous thunderstorms along/ahead
of the front, and in association with the sea breeze. Strong to
locally damaging gusts will be possible, mainly during the afternoon
and evening.

...Southern/central Rockies/High Plains...
Relatively high-based thunderstorms are again expected this
afternoon and evening across parts of the central/southern Rockies
and adjacent High Plains. Localized strong to severe gusts may
accompany these storms, though with relatively modest buoyancy and
weak deep-layer shear, the threat appears too disorganized and
nebulous for probabilities at this time.

..Dean/Wendt.. 07/22/2025

$$

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ACUS01 KWNS 221234
SWODY1
SPC AC 221232

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0732 AM CDT Tue Jul 22 2025

Valid 221300Z - 231200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN PLAINS INTO THE UPPER MISSISSIPPI VALLEY...

...SUMMARY...
Scattered severe thunderstorms will be possible over parts of the
northern Plains into the upper Mississippi Valley later today into
tonight.

...Synopsis...
Large-scale upper ridging will remain anchored over the MS Valley
and Southeast today. A positively tilted upper trough will persist
over the Northwest and northern Rockies, with enhanced southwesterly
mid-level flow continuing though the period over the northern
Plains. At the surface, a weak low is forecast to gradually develop
eastward across western/central SD by this evening, with a lee
trough extending southward from this low across the central High
Plains. A convectively reinforced boundary extending northeastward
from the surface low into northern MN may act as a focus for robust thunderstorm development later today.

...Northern Plains into the Upper Mississippi Valley...
Extensive convective overturning has occurred overnight across the
northern Plains into parts of MN, with scattered to numerous
thunderstorms generally remaining sub-severe while tracking
east-northeastward along/north of the surface front. This activity
has been aided by a southerly low-level jet across the Plains, which
is forecast to gradually weaken though midday. While isolated hail
or strong to severe gusts may occur with ongoing thunderstorms, the
net effect of this convection may be to displace the surface
boundary farther south than most guidance indicates. In the wake of
this early day convection and associated weak mid-level shortwave
trough, heights are forecast to remain neutral or even rise slightly
through the day across much of ND/SD into MN. This weak/nebulous
large-scale forcing casts considerable uncertainty regarding
convective development with eastward extent across the Dakotas into
MN this afternoon and evening.

Even so, it does appear probable that thunderstorms will once again
form along/near the Bighorns in northern WY/southern MT, as a weak
embedded mid-level perturbation and related jet overspread the
northern High Plains. This region will generally be post-frontal,
but steep mid-level lapse rates combined with diurnal heating of the
modestly moist low-level airmass should still aid in the development
of at least weak instability by the time convection initiates this
afternoon. Strong deep-layer shear should support supercells
initially, with associated threat for large to perhaps isolated very
large hail. Some potential should exist for this convection to grow
upscale this evening across parts of the Dakotas and pose a greater
threat for severe/damaging winds overnight. But, uncertainty remains
high regarding the placement of this possible cluster, and whether
it will remain surface-based or elevated.

Farther east into the upper MS Valley, it appears less likely that
robust convection will develop before this evening due to the
stabilizing influence of the ongoing morning activity. If
thunderstorms can develop later, most short-term guidance continues
to suggest that sufficient airmass recovery will occur to support
severe convection with mainly a hail/wind threat. Sufficient
low-level shear should also be present near the front to support
some risk for a tornado. This activity would probably remain tied
close the surface boundary, with less potential for a
forward-propagating MCS into central/southern MN. Accordingly, have
trimmed the southern extent of the Slight Risk in MN. Finally, a MCV
related to extensive convection in KS yesterday is forecast to
develop northeastward across IA this afternoon/evening. Sufficient
instability and shear should be present with this feature to support
an isolated threat for severe thunderstorms, assuming convection can
develop and persist.

...Central High Plains...
Scattered to numerous high-based thunderstorms should develop this
afternoon along/near the surface lee trough extending southward
across the central High Plains. While low/mid-level flow and
deep-layer shear are all expected to remain weak today across this
region due to closer proximity to the upper ridge, low-level lapse
rates should become steepened through the afternoon and early
evening with ample daytime heating. Given the deeply mixed boundary
layer forecast, any of this high-based convection could produce
occasional strong to severe wind gusts. Have therefore expanded the
Marginal Risk southward a bit into eastern CO and western KS to
account for this potential.

...Southeast...
A weak cold front will shift southward today across parts of GA/SC.
A rather moist low-level airmass will be in place ahead of the
front, with daytime heating encouraging the development of moderate
to locally strong instability through the afternoon. Scattered
thunderstorms that develop along/ahead of the front, and along
various sea breeze circulations, may be capable of producing
occasional damaging winds, even though shear will remain weak.

..Gleason/Grams.. 07/22/2025

$$

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ACUS01 KWNS 221632
SWODY1
SPC AC 221630

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1130 AM CDT Tue Jul 22 2025

Valid 221630Z - 231200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN PLAINS INTO THE UPPER MISSISSIPPI VALLEY...

...SUMMARY...
Scattered severe thunderstorms will be possible over parts of the
northern Plains into the upper Mississippi Valley this afternoon
into tonight.

...Northern Plains into the Upper Mississippi Valley...
Visible-satellite imagery late this morning shows extensive cloud
debris and convective outflow from ongoing and early morning shower/thunderstorm activity. A composite outflow/front is draped
from the ND/MN Red River Valley west-southwestward into northwest
SD, with another frontal segment extending into northern WY. Weak to
neutral height rises across the northern Plains this afternoon will
likely not support a northward oscillation of the boundary into
southwest ND.

A belt of moderate to strong southwesterly 500-mb flow overhead the north-central Rockies and adjacent plains will be downstream of a
larger-scale trough pivoting east across the northern Rockies
through tonight. In agreement with earlier forecast thinking, it
appears probable that diurnal storms will favor the general area of
northern WY/southern MT. This region will generally be post-frontal,
but steep mid-level lapse rates and a modestly moist low-level
airmass should still aid in the development of at least weak
instability. Strong deep-layer shear should support supercells
initially, with associated threat for large to perhaps isolated very
large hail. Some potential should exist for this convection to grow
upscale this evening across parts of the Dakotas and pose a greater
threat for severe/damaging winds overnight. But, uncertainty remains
high regarding the placement of this possible cluster, and whether
it will remain surface-based or elevated.

Farther east into the upper MS Valley, it appears less likely that
robust convection will develop before this evening due to the
stabilizing influence of the ongoing morning activity. If
thunderstorms can develop later, most short-term guidance continues
to suggest that sufficient airmass recovery will occur to support
severe convection with mainly a hail/wind threat. Some diurnal
hail/wind threat may develop across IA in association with the lower
MO Valley MCV. Uncertainty remains high regarding this scenario.

...Central High Plains...
Scattered to numerous high-based thunderstorms should develop this
afternoon along/near the surface lee trough extending southward
across the central High Plains. While low/mid-level flow and
deep-layer shear are all expected to remain weak today across this
region due to closer proximity to the upper ridge, heating will
contribute to the development of steep 0-3 km lapse rates. Severe
gusts will be the primary hazard.

...Southeast...
A weak cold front will shift southward today across parts of GA/SC.
A rather moist low-level airmass will be in place ahead of the
front, with daytime heating encouraging the development of moderate
to locally strong instability through the afternoon. Scattered
thunderstorms that develop along/ahead of the front, and along
various sea breeze circulations, may be capable of producing
occasional damaging winds, even though shear will remain weak.

..Smith/Moore.. 07/22/2025

$$

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ACUS01 KWNS 221955
SWODY1
SPC AC 221953

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0253 PM CDT Tue Jul 22 2025

Valid 222000Z - 231200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF THE
NORTHERN PLAINS INTO THE UPPER MISSISSIPPI VALLEY...

...SUMMARY...
Scattered severe thunderstorms will be possible over parts of the
northern Plains into the upper Mississippi Valley this afternoon
into tonight.

...20z Update...
Minor updates were made to the D1 Convective Outlook to reduce the
Marginal Risk area across North Dakota into northern Minnesota where
the front has shifted southward with influence from morning
convection.

Otherwise, the Slight Risk across the northern Plains into the upper
Midwest remains on track. There continues to remain some uncertainty
on what the corridor for greater wind risk will be this evening.
Cloud cover remains across much of the Slight Risk area. It is
mostly clear across southern South Dakota into Wyoming, where
temperatures are warming. Thunderstorm activity has begun across the
high terrain in Montana and Wyoming. See the previous discussion
below for more information.

..Thornton.. 07/22/2025

.PREV DISCUSSION... /ISSUED 1130 AM CDT Tue Jul 22 2025/

...Northern Plains into the Upper Mississippi Valley...
Visible-satellite imagery late this morning shows extensive cloud
debris and convective outflow from ongoing and early morning shower/thunderstorm activity. A composite outflow/front is draped
from the ND/MN Red River Valley west-southwestward into northwest
SD, with another frontal segment extending into northern WY. Weak to
neutral height rises across the northern Plains this afternoon will
likely not support a northward oscillation of the boundary into
southwest ND.

A belt of moderate to strong southwesterly 500-mb flow overhead the north-central Rockies and adjacent plains will be downstream of a
larger-scale trough pivoting east across the northern Rockies
through tonight. In agreement with earlier forecast thinking, it
appears probable that diurnal storms will favor the general area of
northern WY/southern MT. This region will generally be post-frontal,
but steep mid-level lapse rates and a modestly moist low-level
airmass should still aid in the development of at least weak
instability. Strong deep-layer shear should support supercells
initially, with associated threat for large to perhaps isolated very
large hail. Some potential should exist for this convection to grow
upscale this evening across parts of the Dakotas and pose a greater
threat for severe/damaging winds overnight. But, uncertainty remains
high regarding the placement of this possible cluster, and whether
it will remain surface-based or elevated.

Farther east into the upper MS Valley, it appears less likely that
robust convection will develop before this evening due to the
stabilizing influence of the ongoing morning activity. If
thunderstorms can develop later, most short-term guidance continues
to suggest that sufficient airmass recovery will occur to support
severe convection with mainly a hail/wind threat. Some diurnal
hail/wind threat may develop across IA in association with the lower
MO Valley MCV. Uncertainty remains high regarding this scenario.

...Central High Plains...
Scattered to numerous high-based thunderstorms should develop this
afternoon along/near the surface lee trough extending southward
across the central High Plains. While low/mid-level flow and
deep-layer shear are all expected to remain weak today across this
region due to closer proximity to the upper ridge, heating will
contribute to the development of steep 0-3 km lapse rates. Severe
gusts will be the primary hazard.

...Southeast...
A weak cold front will shift southward today across parts of GA/SC.
A rather moist low-level airmass will be in place ahead of the
front, with daytime heating encouraging the development of moderate
to locally strong instability through the afternoon. Scattered
thunderstorms that develop along/ahead of the front, and along
various sea breeze circulations, may be capable of producing
occasional damaging winds, even though shear will remain weak.

$$

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ACUS01 KWNS 230059
SWODY1
SPC AC 230058

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0758 PM CDT Tue Jul 22 2025

Valid 230100Z - 231200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTHERN PLAINS TO UPPER MIDWEST...

...SUMMARY...
Isolated to widely scattered potentially severe thunderstorms may
occur tonight across the northern Plains to Upper Midwest.

...Northern Plains/Upper Midwest...
Severe storms have remained relatively isolated/limited through late
afternoon and early evening, likely attributable to factors such as
a persistence of semi-cool surface temperatures and stratus across
southeast Montana and the western Dakotas, as well as modest overall
forcing and residual mid-level capping regionally. Aided by the
approach of an upstream mid-level trough, some strong to severe
storms may still emerge across southeast Montana and the Big Horns
vicinity of northeast Wyoming. A strengthening south-southwesterly
low-level jet across the central Plains toward the Upper Midwest may
also influence an uptick in storm coverage/intensity tonight across
South Dakota into southern/eastern North Dakota and Minnesota. Bouts
of damaging winds and hail are expected to be the primary hazards
regionally. Regarding short-term severe potential across Iowa, see
Mesoscale Discussion 1757.

..Guyer.. 07/23/2025

$$

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ACUS01 KWNS 230549
SWODY1
SPC AC 230547

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1247 AM CDT Wed Jul 23 2025

Valid 231200Z - 241200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MIDDLE
MISSOURI VALLEY/UPPER MIDWEST TO UPPER MICHIGAN...

...SUMMARY...
Severe storms capable of damaging winds and potentially a tornado
risk are expected across the middle Missouri River Valley and Upper
Midwest to upper Great Lakes, mainly this afternoon and evening.

...Middle Missouri Valley/Upper Midwest to Upper Michigan...
Scattered thunderstorms are expected to be ongoing early today near
and, more so, behind/north of the surface front extending generally southwest-northeastward across South Dakota toward south-central
Minnesota. A few strong/severe storms may occur within this regime
early today across South Dakota/Minnesota, but a more appreciable
severe potential should evolve later in the afternoon as heating and destabilization occur ahead of the front and any residual
outflows/cloud debris.

The net result should be the most aggressive heating/destabilization
across southeast/east-central South Dakota, across the southern
third of Minnesota into central Wisconsin, with 4000+ J/kg MLCAPE
plausible within this corridor. While evolution/disposition of
early-day convection are not entirely certain, a more
supercell-favorable environment with a tornado risk could evolve
this afternoon into evening across eastern Minnesota into west-central/north-central Wisconsin within the low-level jet axis
and near/east of a surface wave. Otherwise, intensifying
thunderstorms and organizing clusters with damaging winds as the
most probable severe-weather hazard are expected to be primary
scenario regionally during the late afternoon and evening.

...Central and northern High Plains...
Within a post-frontal environment, east-northeasterly low-level
winds will exist beneath moderately strong westerlies aloft to yield
relatively long hodographs, with generally 40+ kt effective shear
from the Black Hills/I-90 vicinity northward. This will coincide
with moderate diurnal destabilization, particularly across
interior/eastern Wyoming into southeast Montana and parts of the
western Dakotas. Isolated instances of large hail may occur along
with the possibility of some severe-caliber wind gusts, particularly
if some east/southeastward-moving clusters develop/semi-organize
during the evening.

..Guyer/Wendt.. 07/23/2025

$$

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ACUS01 KWNS 231202
SWODY1
SPC AC 231200

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0700 AM CDT Wed Jul 23 2025

Valid 231300Z - 241200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN PLAINS INTO THE UPPER MIDWEST AND UPPER GREAT LAKES...

...SUMMARY...
Severe thunderstorms capable of producing damaging winds and
potentially a tornado risk are expected across the middle Missouri
Valley and Upper Midwest to upper Great Lakes, mainly this afternoon
and evening. Large hail may occur with supercells later today across
parts of the northern High Plains.

...Synopsis...
A positively tilted upper trough over central Canada and the
northern Rockies/High Plains will advance slowly eastward today,
impinging on an upper ridge that will remain over much of the
Southeast, Mid-Atlantic, and OH Valley. A quasi-stationary surface
front arcing northeastward from a weak low in central SD should make
some southeastward progress as a cold front today across portions of
the northern Plains and Upper Midwest, as a low-amplitude mid-level
shortwave trough advances eastward across these regions through the
period. This front will likely serve as a continued focus for strong
to severe convection today.

...Mid Missouri Valley into the Upper Midwest/Great Lakes...
Scattered to numerous thunderstorms are occurring this morning,
generally along/north of the surface front across north-central SD
into northern MN. This activity may tend to remain somewhat elevated
through most of the morning, but it may still pose an isolated
severe hail/wind threat given the presence of moderate MUCAPE and
sufficient deep-layer shear to support updraft organization. A
separate band of elevated convection is ongoing along/near the NE/SD
border. This activity is likely more tied to low-level warm
advection, and it remains somewhat unclear what affect these
thunderstorms will have on the warm sector later today if they can
persist.

Regardless of the uncertainty with the evolution and intensity of
ongoing thunderstorms this morning, daytime heating along/south of
the front will likely aid in strong to locally extreme instability
developing by early to mid afternoon, as a very moist airmass is
already in place across the Upper Midwest per area surface
observations. Mid-level flow and related deep-layer shear will tend
to become more modest with southward extent along the surface front.
But, they should still be sufficient to promote organized severe
convection, especially across MN into WI.

Current expectations are for multiple bowing clusters/line segments
to develop this afternoon along much of the front from NE into
eastern SD and MN. Scattered severe/damaging winds will likely be
the primary threat with this activity as it spreads eastward into
parts of northern WI and the U.P of MI this evening. Isolated hail
may occur with initial development. Modest low-level shear may also
support some tornado threat, mainly across parts of MN into WI where
a southwesterly low-level jet should be focused later this
afternoon/early evening. To account for both the ongoing activity
and recent guidance trends suggesting an earlier/westward start to
robust thunderstorms this afternoon along the front, the Marginal
and Slight Risks have been expanded westward some across NE/SD/MN
with this update.

...Northern/Central High Plains...
Within a post-frontal environment, east-northeasterly low-level
winds will persist beneath moderately strong westerlies aloft to
yield relatively long/straight hodographs at mid/upper levels, with
generally 40-50 kt of effective bulk shear from the Black Hills
vicinity northward. This will coincide with moderate diurnal
destabilization, particularly across interior/eastern Wyoming into
southeast Montana and parts of the western Dakotas. Scattered large
hail may occur with any sustained supercells, along with the
possibility of some severe wind gusts, particularly if
east-southeastward moving clusters can develop this evening. With
increased confidence in multiple supercells occurring this
afternoon/evening across northeast WY/southeast MT into western SD,
have introduced a Slight Risk mainly for large hail potential.

..Gleason/Grams.. 07/23/2025

$$

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ACUS01 KWNS 231624
SWODY1
SPC AC 231623

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1123 AM CDT Wed Jul 23 2025

Valid 231630Z - 241200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN HIGH PLAINS...AND NEBRASKA INTO THE UPPER GREAT
LAKES...

...SUMMARY...
Scattered severe thunderstorms capable of producing damaging winds
and potentially a tornado risk are possible across the Upper
Midwest, mainly this afternoon and evening. Large hail may occur
with supercells late today across parts of the northern High Plains.

...Mid Missouri Valley into the Upper Midwest/Great Lakes...
Visible satellite/radar composite shows scattered thunderstorms late
this morning from eastern SD into western WI, generally near and
east of a surface low analyzed near the SD/MN border. A cold front
extending from northern MN southwestward into the central High
Plains will continue east-southeastward and provide a focus for
additional storm development this afternoon/evening. Due in part to appreciable convection this morning and its related airmass
influence across the Upper Midwest, uncertainty remains regarding
the evolution of midday thunderstorm clusters and their associated
severe risk this afternoon as the airmass immediately east/southeast
of this activity continues to destabilize.

A plume of richer low-level moisture (surface dewpoints in the mid
70s F) extends northward from the mid MS Valley into the upper MS
Valley. Model guidance maintains a belt of moderate southwesterly
800-650 mb flow (30-35 kt) across the MN/IA/WI vicinity with
slightly weaker flow indicated in the upper troposphere. The
resultant hodograph structure should promote more linear
configurations of storms. Models show the development of a more southwest-northeast oriented convective band later this afternoon
across this region, which may subdue otherwise greater potential for
severe gusts (being not oriented orthogonal to the mean wind in
800-650 mb layer), given the development of a very unstable boundary
layer in areas void of convective overturning.

Scattered severe/damaging winds appear to be the primary severe
hazard but a tornado or two is possible, especially across MN into
the WI vicinity. Storms are likely to develop farther southwest
along the front in NE but weaker shear with south extent will limit
the overall convective organization. However, severe gusts will
probably occur with the more intense cores and surges with a linear
band of storms through the evening before this activity gradually
weakens.

...Northern/Central High Plains...
No change was made to this portion of the outlook. A
moist/post-frontal environment will favor scattered storm
development later this afternoon. Relatively long/straight
hodographs at mid/upper levels from the Black Hills into northeast
WY will promote supercell development with the stronger updrafts.
Large hail and severe gusts will be the primary hazards. Farther
south, weaker flow will result in less organized storm modes, but
isolated severe gusts/hail may occur with the stronger storms
through early-mid evening.

..Smith/Supinie.. 07/23/2025

$$

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ACUS01 KWNS 231944
SWODY1
SPC AC 231943

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0243 PM CDT Wed Jul 23 2025

Valid 232000Z - 241200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THERE IS A SLIGHT
RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN HIGH
PLAINS AND NEBRASKA INTO THE UPPER GREAT LAKES...

...SUMMARY...
Scattered severe thunderstorms capable of producing damaging winds
and potentially a tornado risk are possible across the Upper
Midwest, mainly this afternoon and evening. Large hail may occur
with supercells late today across parts of the northern High Plains.

...20z Update...
The primary forecast amendment for this update is a reduction in
severe probabilities across portions of northern MN and WI where the
primary front and convective clusters/bands have passed and
conditions are slowly stabilizing within the post-frontal regime.
Across WI, 5% tornado probabilities have been adjusted southward to
better align with recent convective trends and where short-range
guidance shows the best overlap of low-level theta-e advection and
wind shear later this evening. Although convective mode will be the
primary modulating factor in the overall tornado threat, STP values
should increase to between 1-2 later this evening as the nocturnal
jet strengthens and should support at least some tornado potential.

Elsewhere, the forecast remains on track per the previous discussion
below. GOES IR imagery and echo top data shows an uptick in
convective intensity across southeast MN and northern WI, and early
stages of convective initiation are noted along the front
southwestward into NE. These trends suggest a severe threat remains
across the Plains/upper MS Valley regions. See MCDs #1761 and #1762
for additional details regarding the severe threat across portions
of the northern High Plains and central NE.

..Moore.. 07/23/2025

.PREV DISCUSSION... /ISSUED 1123 AM CDT Wed Jul 23 2025/

...Mid Missouri Valley into the Upper Midwest/Great Lakes...
Visible satellite/radar composite shows scattered thunderstorms late
this morning from eastern SD into western WI, generally near and
east of a surface low analyzed near the SD/MN border. A cold front
extending from northern MN southwestward into the central High
Plains will continue east-southeastward and provide a focus for
additional storm development this afternoon/evening. Due in part to appreciable convection this morning and its related airmass
influence across the Upper Midwest, uncertainty remains regarding
the evolution of midday thunderstorm clusters and their associated
severe risk this afternoon as the airmass immediately east/southeast
of this activity continues to destabilize.

A plume of richer low-level moisture (surface dewpoints in the mid
70s F) extends northward from the mid MS Valley into the upper MS
Valley. Model guidance maintains a belt of moderate southwesterly
800-650 mb flow (30-35 kt) across the MN/IA/WI vicinity with
slightly weaker flow indicated in the upper troposphere. The
resultant hodograph structure should promote more linear
configurations of storms. Models show the development of a more southwest-northeast oriented convective band later this afternoon
across this region, which may subdue otherwise greater potential for
severe gusts (being not oriented orthogonal to the mean wind in
800-650 mb layer), given the development of a very unstable boundary
layer in areas void of convective overturning.

Scattered severe/damaging winds appear to be the primary severe
hazard but a tornado or two is possible, especially across MN into
the WI vicinity. Storms are likely to develop farther southwest
along the front in NE but weaker shear with south extent will limit
the overall convective organization. However, severe gusts will
probably occur with the more intense cores and surges with a linear
band of storms through the evening before this activity gradually
weakens.

...Northern/Central High Plains...
No change was made to this portion of the outlook. A
moist/post-frontal environment will favor scattered storm
development later this afternoon. Relatively long/straight
hodographs at mid/upper levels from the Black Hills into northeast
WY will promote supercell development with the stronger updrafts.
Large hail and severe gusts will be the primary hazards. Farther
south, weaker flow will result in less organized storm modes, but
isolated severe gusts/hail may occur with the stronger storms
through early-mid evening.

$$

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ACUS01 KWNS 240109
SWODY1
SPC AC 240107

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0807 PM CDT Wed Jul 23 2025

Valid 240100Z - 241200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF NE
INTO THE UPPER MIDWEST...AND ALSO FOR NORTHWEST LOWER MI...

...SUMMARY...
Strong to severe storms remain possible this evening from parts of
Nebraska into the upper Midwest and northern Lower Michigan, and
also across the northern High Plains.

...NE into the Upper Midwest and northern Lower MI...
Strong to severe storms are ongoing this evening from central NE
into southern MN/northern IA. Very rich low-level moisture and
strong buoyancy remain in place along/south of a composite
front/outflow, though deep-layer flow/shear is relatively modest
along/south of the boundary. Considering the favorable buoyancy,
some threat for damaging gusts will persist through the evening,
especially if any stronger clusters or bowing segments (like the one
currently in central NE) become established within the larger region
of ongoing convection. Isolated hail will also be possible with the
strongest updrafts.

Farther east, a well-defined bowing storm cluster is moving across
Lake Michigan toward northern Lower Michigan. Decreasing buoyancy
and increasing CINH with eastward extent should eventually result in
a weakening trend with this system, but some threat for at least
localized wind damage may continue into parts of northwest and
possibly north-central lower MI this evening.

...Northern High Plains...
Ongoing storms approaching the NE Panhandle should generally weaken
with time as they encounter decreasing instability, though localized
hail and severe gusts cannot be ruled out this evening. Farther
west, isolated strong to severe storms remain possible across
northeast WY and vicinity this evening, within a modestly unstable
but favorably sheared environment.

..Dean.. 07/24/2025

$$

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ACUS01 KWNS 240558
SWODY1
SPC AC 240556

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1256 AM CDT Thu Jul 24 2025

Valid 241200Z - 251200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF
MICHIGAN AND THE LOWER GREAT LAKES INTO THE
MIDWEST...CENTRAL/SOUTHERN PLAINS...AND HIGH PLAINS...

...SUMMARY...
Locally damaging thunderstorm wind gusts will be possible from the
Great Lakes to the central and southern Plains, mainly this
afternoon and evening. Isolated severe storms will also pose a risk
of large hail and severe wind gusts over the northern and central
High Plains.

...Lower MI into the lower Great Lakes...
The Marginal Risk has been maintained across lower MI and adjacent
parts of the Great Lakes, though higher wind probabilities may
eventually be needed, if confidence increases in a sufficient
coverage of organized storm development later today into this
evening.

Multiple low-amplitude midlevel vorticity maxima (including
potentially one or more MCVs) will move across parts of the Great
Lakes region later today, within a broader large-scale upper-level
trough. A cold front will move southeastward across parts of the
upper Midwest and Great Lakes through the day into the evening.

Diurnal heating of a richly moist airmass will result in the
development of moderate buoyancy along/ahead of the front this
afternoon. This destabilization will occur beneath moderate
low/midlevel southwesterly flow (25-40 kt in the 850-700 mb layer).
The resulting environment will be favorable for outflow-dominant
storm clusters capable of wind damage.

However, details of storm coverage and timing remain uncertain, due
to weak frontal convergence and generally modest large-scale ascent,
outside of the potential influence of any MCVs. There is some
potential for development relatively early in the day across
central/northern Lower MI, when somewhat steeper midlevel lapse
rates may still be in place. This scenario may be the greatest
relative threat for organized storms, though guidance varies
regarding the coverage of storms through early afternoon. Otherwise,
midlevel temperatures will tend to warm by later afternoon, though
any stronger cells/clusters would still be capable of producing wind
damage as low-level lapse rates steepen.

Storms may spread into parts of western NY from Ontario late this
evening. While a general weakening trend is expected by this time,
strong to locally damaging gusts cannot be ruled out late tonight
before convection subsides.

...Northern MO/IL/IN into central/eastern KS and northern OK...
Scattered storm development is expected this afternoon and evening
from central/eastern KS and northern OK into parts of northern
MO/IL/IN, along and ahead of a cold front. Somewhat enhanced
low/midlevel flow will be present across northern IL/IN early in the
day, but gradual weakening of flow is generally forecast with time.
Farther southwest, flow is forecast to remain rather weak into
northern MO and the central/southern Plains. As a result, storm
organization may tend to be limited, but moderate to strong buoyancy
and large PW (potentially 2 inches or greater) will support a threat
of localized downbursts. One or more small clusters could develop
and pose a threat for more concentrated wind damage, but confidence
in the details of this potential scenario remains low.

...High Plains...
Moderate buoyancy is expected to develop across parts of the central
and northern High Plains this afternoon. Large-scale ascent will
generally be nebulous in the wake of a departing shortwave trough,
but at least isolated storm development is possible near the
adjacent higher terrain. Effective shear of 30-40 kt will support
some storm organization. Initial discrete cells may pose a threat of
hail, while some outflow amalgamation could eventually occur, with a
threat of strong to locally severe gusts spreading eastward into the
evening.

Farther south, scattered to numerous thunderstorms are expected into
parts of the southern High Plains. Deep-layer shear will be weak
across this region, but localized strong to severe outflow gusts
will be possible.

..Dean/Thornton.. 07/24/2025

$$

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ACUS01 KWNS 241232
SWODY1
SPC AC 241230

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0730 AM CDT Thu Jul 24 2025

Valid 241300Z - 251200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
THE GREAT LAKES INTO THE MIDWEST...CENTRAL/SOUTHERN PLAINS...AND
HIGH PLAINS...

...SUMMARY...
Locally damaging thunderstorm wind gusts will be possible from parts
of the Great Lakes to the central and southern Plains, mainly this
afternoon and evening. Isolated severe storms will also pose a risk
of hail and severe wind gusts over portions of the northern and
central High Plains.

...Synopsis...
Modestly enhanced westerly mid-level flow will be maintained today
between an upper trough progressing slowly eastward over central
Canada and the north-central CONUS, and upper ridging across the
Southeast and Mid-Atlantic. Multiple mid-level MCVs evident on
satellite and radar should move generally east-northeastward across
parts of the Midwest and Great Lakes today. At the surface, a
convectively reinforced front will be draped from Ontario/Quebec
southwestward to the southern Plains. This front will likely serve
as a focused for additional scattered to numerous thunderstorms this
afternoon and evening, some of which could become strong to severe
on an isolated basis.

...Great Lakes into the Midwest and Central/Southern Plains...
A moist and rather unstable airmass will exist along/ahead of the
front today, as diurnal heating aids in the gradual steepening of
low-level lapse rates. Stronger mid-level flow and related
deep-layer shear should be present across parts of MI and vicinity.
Some enhancement to the low/mid-level winds and modest ascent
associated with an MCV over northeast WI this morning may also aid
in thunderstorm development and organization downstream into parts
of northern Lower MI by early afternoon. This area appears to have
the best combination of forecast instability and shear, and any
thunderstorms which can form here could become severe while posing a
threat for both isolated hail and damaging winds. However, low-level
flow along/near the front is generally expected to remain veered to southwesterly, which should limit low-level convergence to some
extent. Therefore, confidence in overall coverage of severe
convection remains too low to include greater severe probabilities
across northern Lower MI at this time.

Mid-level flow and effective bulk shear values will decrease with
southward extent across the Midwest into the southern Plains, away
from any remnant MCV influences. This should tend to limit updraft
organization with thunderstorms that develop this afternoon across
these regions. Still, some potential should exist for loosely
organized clusters given the linear low-level forcing. And with
steep low-level lapse rates and moderate to strong instability, some
of this convection may be capable of producing strong to locally
severe winds through the early evening hours before eventually
weakening with the loss of daytime heating.

...High Plains...
Moderate instability should develop across parts of the
northern/central High Plains this afternoon. Large-scale ascent will
be weak behind a departing mid-level shortwave trough. Even so,
convective development should occur near the adjacent higher terrain
this afternoon. Effective shear of 25-40 kt will support some
updraft organization. Initially discrete cells may pose an isolated
threat for hail. Some outflow amalgamation/mergers could eventually
occur, with a threat of strong to locally severe gusts spreading
eastward into the evening before convection eventually weakens.
Farther south across portions of the southern High Plains, scattered
to numerous thunderstorms are also expected to develop this
afternoon/early evening. Deep-layer shear will remain weak across
this region, but localized strong to severe outflow gusts may still
be possible.

..Gleason/Grams.. 07/24/2025

$$

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ACUS01 KWNS 241636
SWODY1
SPC AC 241634

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1134 AM CDT Thu Jul 24 2025

Valid 241630Z - 251200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE MIDWEST/GREAT LAKES...

...SUMMARY...
Locally damaging thunderstorm wind gusts are possible from parts of
the Great Lakes to the central and southern Plains this afternoon
and evening. Isolated severe storms will also pose a risk of hail
and severe wind gusts over portions of the northern and central High
Plains.

...Northern Lower Michigan...
Ahead of an MCV, a well-organized cluster of storms will pose at a
short-term severe risk across far northern Lower Michigan early this
afternoon, although there is some potential for additional
development southwestward along the front this afternoon.

...Midwest/Lake Michigan vicinity to south-central Plains...
Aside from an MCV nearing northern Lake Michigan, at least one
additional eastward-moving MCV exists across eastern Iowa, nearing
the southwest Wisconsin/northwest Illinois border vicinity as of
midday. Some multi-layer cloud debris still persists, and a
pre-frontal veering of winds (westerly component) has occurred in
some areas. However, heating of a very moist air mass (70s F surface
dewpoints) will lead to strong destabilization (2500-4000 J/kg
MLCAPE) and relatively weak boundary-layer inhibition this afternoon
near/ahead of the front. Most 12z global guidance/HREF members are
more aggressive in the coverage/intensity of convection than morning HRRR/RRFS/MPAS runs, particularly for northern portions of
Illinois/Indiana into Lower Michigan.

Where deep convection does develop/sustain this afternoon, MCV-aided enhancement of low/mid-tropospheric flow will support some
well-organized bands/clusters of storms with wind damage as the most
common severe risk across northern Missouri, northern portions of Illinois/Indiana, into Lower Michigan. A more localized/pulse-type
severe risk is anticipated farther southwest into southern
Kansas/northwest Oklahoma.

...High Plains...
Moderate instability will develop across parts of the
northern/central High Plains this afternoon. Large-scale ascent will
tend to be weak behind a departing mid-level shortwave trough. Even
so, convective development should occur near the adjacent higher
terrain this afternoon. Effective shear of 25-40 kt will support
some updraft organization. Initially discrete cells may pose an
isolated threat for hail. Some outflow amalgamation/mergers could
eventually occur, with a threat of strong to locally severe gusts
spreading eastward into the evening before convection eventually
weakens. Farther south across portions of the southern High Plains,
scattered to numerous thunderstorms are also expected to develop
this afternoon/early evening. Deep-layer shear will remain weak
across this region, but localized strong to severe outflow gusts may
still be possible.

..Guyer/Supinie.. 07/24/2025

$$

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ACUS01 KWNS 241954
SWODY1
SPC AC 241952

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0252 PM CDT Thu Jul 24 2025

Valid 242000Z - 251200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THERE IS A SLIGHT
RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MIDWEST/GREAT
LAKES...

...SUMMARY...
Locally damaging thunderstorm wind gusts are possible from parts of
the Great Lakes to the central and southern Plains this afternoon
and evening. Isolated severe storms will also pose a risk of hail
and severe wind gusts over portions of the northern and central High
Plains.

...20z Update...
The previous forecast largely remains on track. Thunderstorm
development is underway across portions of northern IL, which should
intensify and track into northern IN and southern MI through the
evening hours. Severe hail/wind risk probabilities were reduced
across far northern lower MI due to the recent passage of deep
convection and an influx of cooler/lower theta-e air. See the
previous discussion below as well as MCDs #1771 and #1772 for
additional details.

..Moore.. 07/24/2025

.PREV DISCUSSION... /ISSUED 1134 AM CDT Thu Jul 24 2025/

...Northern Lower Michigan...
Ahead of an MCV, a well-organized cluster of storms will pose at a
short-term severe risk across far northern Lower Michigan early this
afternoon, although there is some potential for additional
development southwestward along the front this afternoon.

...Midwest/Lake Michigan vicinity to south-central Plains...
Aside from an MCV nearing northern Lake Michigan, at least one
additional eastward-moving MCV exists across eastern Iowa, nearing
the southwest Wisconsin/northwest Illinois border vicinity as of
midday. Some multi-layer cloud debris still persists, and a
pre-frontal veering of winds (westerly component) has occurred in
some areas. However, heating of a very moist air mass (70s F surface
dewpoints) will lead to strong destabilization (2500-4000 J/kg
MLCAPE) and relatively weak boundary-layer inhibition this afternoon
near/ahead of the front. Most 12z global guidance/HREF members are
more aggressive in the coverage/intensity of convection than morning HRRR/RRFS/MPAS runs, particularly for northern portions of
Illinois/Indiana into Lower Michigan.

Where deep convection does develop/sustain this afternoon, MCV-aided enhancement of low/mid-tropospheric flow will support some
well-organized bands/clusters of storms with wind damage as the most
common severe risk across northern Missouri, northern portions of Illinois/Indiana, into Lower Michigan. A more localized/pulse-type
severe risk is anticipated farther southwest into southern
Kansas/northwest Oklahoma.

...High Plains...
Moderate instability will develop across parts of the
northern/central High Plains this afternoon. Large-scale ascent will
tend to be weak behind a departing mid-level shortwave trough. Even
so, convective development should occur near the adjacent higher
terrain this afternoon. Effective shear of 25-40 kt will support
some updraft organization. Initially discrete cells may pose an
isolated threat for hail. Some outflow amalgamation/mergers could
eventually occur, with a threat of strong to locally severe gusts
spreading eastward into the evening before convection eventually
weakens. Farther south across portions of the southern High Plains,
scattered to numerous thunderstorms are also expected to develop
this afternoon/early evening. Deep-layer shear will remain weak
across this region, but localized strong to severe outflow gusts may
still be possible.

$$

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ACUS01 KWNS 250101
SWODY1
SPC AC 250059

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0759 PM CDT Thu Jul 24 2025

Valid 250100Z - 251200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
KS/NORTHWEST OK NORTHEASTWARD INTO THE LOWER GREAT LAKES...AND ALSO
ACROSS THE HIGH PLAINS...

...SUMMARY...
Locally damaging thunderstorm wind gusts remain possible tonight
from parts of Missouri into the lower Great Lakes region. Isolated
hail and strong to severe gusts are also possible across parts of
the central and northern High Plains.

...Parts of MO into the lower Great Lakes...
A loosely organized MCS has developed across parts of northeast MO
this evening. This system may continue moving east-northeast along a
surface boundary tonight, aided by very rich downstream moisture and
moderate buoyancy (as observed in the 00Z ILX sounding). While this
system has largely remained subsevere thus far, and low/midlevel
flow is forecast to remain relatively modest, locally damaging gusts
cannot be ruled out as it approaches parts of central/northern IL
and northwest IN later tonight.

Farther east, convection has generally weakened or moved into
Ontario from southern lower MI this evening. Strong storms remain
over parts of southeast Ontario, and these storms may approach parts
of western NY with isolated strong to locally damaging gusts before
subsiding.

...Central/northern High Plains...
Widely scattered strong to locally severe storms may continue
through at least dusk across parts of the central and northern High
Plains, within a moderately unstable environment. Effective shear of
25-35 kt will support potential for hail with the strongest discrete
cells, while isolated strong to severe gusts also remain possible,
especially if any notable outflow consolidation occurs later this
evening.

..Dean.. 07/25/2025

$$

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ACUS01 KWNS 250602
SWODY1
SPC AC 250600

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Fri Jul 25 2025

Valid 251200Z - 261200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR MUCH OF NORTH
DAKOTA...

...SUMMARY...
Scattered strong to severe thunderstorms will pose a risk of
damaging wind gusts across parts of New England and the northern Mid
Atlantic later today. Severe storms will also be possible across
much of North Dakota.

...Northeast into the northern Mid Atlantic...
A vigorous mid/upper-level shortwave trough will move across
southern Quebec and northern New England later today. A cold front
will move across the Northeast and northern Mid Atlantic through the
day and into the evening. Moderate buoyancy is expected to develop
along/ahead of the front during the afternoon. Storm coverage is
somewhat uncertain due to veered low-level flow and relatively weak
frontal convergence, but isolated to widely scattered storm
development will be possible along/ahead of the front. Effective
shear of 25-35 kt will be favorable for some storm organization, and
a few organized clusters and/or marginal supercells may develop,
with a primary threat of damaging gusts during the afternoon and
evening before convection weakens or moves offshore.

...Northern Great Plains...
A midlevel shortwave trough and surface low will move eastward
across parts of AB/SK today. A surface trough will extend southward
from the low across the northern High Plains vicinity. Relatively
rich low-level moisture will stream northward ahead of the surface
trough, beneath steepening midlevel lapse rates. Moderate buoyancy
may develop as far west as eastern MT this afternoon, with very
strong buoyancy (MLCAPE of 2500-4000 J/kg) expected over the
Dakotas.

Stronger large-scale ascent will be across Canada, resulting in
uncertainty regarding storm coverage and evolution during the
afternoon and evening. The bulk of 00Z HREF guidance depicts at
least isolated development near the surface trough across parts of
southeast MT, potentially aided by one or more low-amplitude
midlevel vorticity maxima moving through southwesterly flow aloft.
Some guidance also initiates storms farther east into
central/eastern ND, within a weakly capped but also weakly forced
environment.

Deep-layer flow will be relatively modest, but sufficient to support
effective shear of 25-35 kt. Initially high-based convection across
eastern MT may intensify as it moves eastward into ND, with some
potential for development of a storm cluster or MCS capable of
producing strong to severe gusts. Any diurnal development across central/eastern ND would pose a threat of hail, localized severe
gusts, and possibly a tornado, given modestly enlarged low-level
hodographs. A Slight Risk has been added where there is sufficient
consensus among CAM and global guidance for storm development within
a generally favorable environment.

...Central Plains into the Midwest...
Multiple MCVs may impact areas from the central Plains into the
Midwest later today. The most prominent of these is expected to move
northeast across parts of KS, within a very moist and unstable
environment. Deep-layer shear may become sufficient for organized
clusters or marginal supercell structures, with a threat of
localized damaging gusts. Depending on the extent of low-level SRH
enhancement (which varies among guidance), a tornado may also be
possible.

Other MCVs may move from parts of MO/IL into IN/OH through the day
and into the evening. Their impact on organized severe potential is
uncertain, but if sufficient destabilization can occur ahead of
these features, then localized wind damage will be possible.

..Dean/Squitieri.. 07/25/2025

$$

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ACUS01 KWNS 251255
SWODY1
SPC AC 251253

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0753 AM CDT Fri Jul 25 2025

Valid 251300Z - 261200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
EVENING FOR MUCH OF NORTH DAKOTA...AND FOR PORTIONS OF SOUTHERN NEW
ENGLAND INTO THE NORTHERN MID-ATLANTIC REGION...

...SUMMARY...
Scattered strong to severe thunderstorms will pose a risk of
damaging wind gusts across parts of New England and the northern Mid
Atlantic later today. Severe storms will also be possible across
much of North Dakota.

...Northeast States...
Morning water vapor imagery shows a fast-moving shortwave trough
progressing eastward across Ontario. The associated cold front will
move through the St Lawrence Valley this morning and southward
across New England this afternoon. Relatively hot/humid conditions
ahead of the front will lead to widely scattered afternoon
thunderstorms across southern New England and eastern NY/PA. These
storms will track southeastward toward the coast through the early
evening. Coverage of intense storms is uncertain, but conditions
will be favorable for gusty/damaging winds in the cells that form.

...Northern Plains...
An upper ridge remains centered over the central Plains, with a weak southern-stream trough currently moving across UT into WY. Weak
lift and increased mid-level moisture ahead of the system will aid
in the development of scattered thunderstorms by late afternoon
across parts of eastern MT/northeast WY. Thermodynamic parameters
appear favorable for large hail in the stronger cells. Model
guidance varies on handling this activity as it spreads eastward.
However, it appears reasonable that portions of this early activity
will persist through the evening and pose a risk of hail and locally
damaging winds across parts of ND. Later CAM solutions will
hopefully help better focus this threat area.

...KS/MO...
A large area of overnight convection has resulted in a
convectively-aided shortwave trough that will move into eastern KS
this afternoon. Thunderstorms will likely re-develop near/east of
the remnant MCV and track into western MO during the evening.
Assuming sufficient heating can occur this afternoon along the
southeastern edge of the remnant clouds, a corridor of MRGL severe
threat will likely develop. Isolated damaging wind gusts would be
the main concern.

..Hart/Grams.. 07/25/2025

$$

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ACUS01 KWNS 251644
SWODY1
SPC AC 251642

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1142 AM CDT Fri Jul 25 2025

Valid 251630Z - 261200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHEAST...NORTHERN PLAINS...AND PARTS OF EASTERN KANSAS/WESTERN
MISSOURI...

...SUMMARY...
Scattered strong to severe thunderstorms will pose a risk of
damaging wind gusts across parts of New England and the northern
Mid-Atlantic States this afternoon. Severe storms will also be
possible across much of North Dakota as well as eastern Kansas into
western Missouri.

...Northeast/Mid-Atlantic States...
Midday vapor imagery shows a fast-moving shortwave trough
progressing eastward into Quebec. An associated cold front will move south-southeastward across New England this afternoon. Relatively
hot/humid conditions ahead of the front will lead to widely
scattered afternoon thunderstorms across southern New England and
eastern portions of New York/Pennsylvania. These storms will track southeastward toward the coast through the early evening with
damaging winds possible.

...Northern Plains including North Dakota...
An upper ridge remains centered over the central Plains, with a weak southern-stream trough currently moving across Utah into Wyoming.
Weak lift and increased mid-level moisture ahead of the system will
aid in the development of scattered thunderstorms by late afternoon
across parts of eastern Montana and northeast Wyoming. Thermodynamic
parameters are favorable for large hail in the stronger cells. It
seems that these storms will tend to persist east-northeastward this
evening and pose a risk of hail and locally damaging winds across
North Dakota.

...Eastern Kansas/western Missouri...
Regional WSR-88D VWP data continues to sample modestly enhanced low/mid-tropospheric flow in relation to a slow-moving MCV, notable
from KEAX where 35-40 kt west-southwesterly flow persists between
3-5 km AGL. With a very moist air mass in place (low to middle 70s F
surface dewpoints), intensifying storms could include supercells
given some likely persistence of the enhanced flow field. Especially
with a convectively reinforced surface boundary, a semi-focused
corridor of damaging winds and brief tornado potential could evolve
this afternoon into early evening.

...Northern California/western Nevada...
Aside from the dry thunderstorm potential (see Fire Weather Day 1
Outlook), sufficient moisture/buoyancy may exist on the eastern and
northern periphery of the slow-moving upper low, where mid-level
temperatures (-12C at 500mb) are semi-cool, to allow for some hail
and/or convectively enhanced wind gusts this afternoon through
around sunset.

..Guyer/Supinie.. 07/25/2025

$$

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ACUS01 KWNS 251959
SWODY1
SPC AC 251957

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0257 PM CDT Fri Jul 25 2025

Valid 252000Z - 261200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTHEAST AND MID ATLANTIC...PARTS OF THE MID MISSOURI VALLEY...AND
ACROSS THE NORTHERN PLAINS....

...SUMMARY...
Scattered strong to severe thunderstorms remain capable of damaging
wind gusts across parts of New England and the northern Mid-Atlantic
States this afternoon/evening. Severe storms will also be possible
across much of North Dakota as well as eastern Kansas into western
Missouri.

...20z Update Northeast...
Scattered to numerous thunderstorms ongoing ahead of a weak cold
front across the Northeast and northern Mid Atlantic states will
continue to pose a risk for isolated damaging gusts through this
evening. The main focus for storm development/intensification along
the front will continue to shift southeastward this afternoon.
Trimming was done to the MRGL area mainly where the wind shift has
already moved offshore. Otherwise the SLGT risk area was adjusted to
better match the higher storm coverage and threat for damaging
gusts.

...KS/MO...
To the west, scattered severe storms should continue to
develop/intensify this afternoon ahead of an MCV/shortwave trough
across parts of KS and MO. Very moist surface conditions are present
with mid 70s F dewpoints contributing to moderate destabilization
despite weak low and mid-level lapse rates. Enhanced mid-level wind
fields observed by area VADs should support a few stronger storms
including supercells capable of damaging gusts and possibly brief
tornadoes this afternoon and evening.

...Great Basin...
Isolated to scattered high-based thunderstorms remain likely across
northern CA and western NV this evening. Steep low-level lapse rates
will favor dry microburst potential with these storms or any more
persistent clusters of storms able to evolve. Have adjusted the MRGL
risk slightly west to better capture storms developing near the
higher terrain.

Otherwise, see the previous discussion for additional information.

..Lyons.. 07/25/2025

.PREV DISCUSSION... /ISSUED 1142 AM CDT Fri Jul 25 2025/

...Northeast/Mid-Atlantic States...
Midday vapor imagery shows a fast-moving shortwave trough
progressing eastward into Quebec. An associated cold front will move south-southeastward across New England this afternoon. Relatively
hot/humid conditions ahead of the front will lead to widely
scattered afternoon thunderstorms across southern New England and
eastern portions of New York/Pennsylvania. These storms will track southeastward toward the coast through the early evening with
damaging winds possible.

...Northern Plains including North Dakota...
An upper ridge remains centered over the central Plains, with a weak southern-stream trough currently moving across Utah into Wyoming.
Weak lift and increased mid-level moisture ahead of the system will
aid in the development of scattered thunderstorms by late afternoon
across parts of eastern Montana and northeast Wyoming. Thermodynamic
parameters are favorable for large hail in the stronger cells. It
seems that these storms will tend to persist east-northeastward this
evening and pose a risk of hail and locally damaging winds across
North Dakota.

...Eastern Kansas/western Missouri...
Regional WSR-88D VWP data continues to sample modestly enhanced low/mid-tropospheric flow in relation to a slow-moving MCV, notable
from KEAX where 35-40 kt west-southwesterly flow persists between
3-5 km AGL. With a very moist air mass in place (low to middle 70s F
surface dewpoints), intensifying storms could include supercells
given some likely persistence of the enhanced flow field. Especially
with a convectively reinforced surface boundary, a semi-focused
corridor of damaging winds and brief tornado potential could evolve
this afternoon into early evening.

...Northern California/western Nevada...
Aside from the dry thunderstorm potential (see Fire Weather Day 1
Outlook), sufficient moisture/buoyancy may exist on the eastern and
northern periphery of the slow-moving upper low, where mid-level
temperatures (-12C at 500mb) are semi-cool, to allow for some hail
and/or convectively enhanced wind gusts this afternoon through
around sunset.

$$

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ACUS01 KWNS 260102
SWODY1
SPC AC 260101

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0801 PM CDT Fri Jul 25 2025

Valid 260100Z - 261200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF
NORTH DAKOTA AND VICINITY...

...SUMMARY...
Scattered strong to severe thunderstorms remain capable of damaging
wind gusts and large hail across portions of the northern Plains.
Isolated strong to severe storms will also be possible from the
mid-Atlantic west through the Ohio Valley and central/southern
Plains, and across northern California and northwest Nevada.

...Northeast/mid-Atlantic...
Isolated strong/severe storms continue across PA in advance of a
weak frontal boundary, while storms farther east continue to move
offshore across portions of NJ/NY. Latest objective analysis shows
pockets of moderate instability (MLCAPE at or above 2000 J/kg)
across the northern Delmarva Peninsula, and some potential for a
stronger storm or two will exist in this area this evening. Overall,
the severe threat should remain isolated through the remainder of
the evening, and diminish thereafter with the onset of gradual
nocturnal cooling/increasing CINH.

...Western Oklahoma/Eastern Kansas into the OH Valley...
A few clusters of thunderstorms continue within a moderate/strongly
unstable air mass in the vicinity of a nearly stationary frontal
boundary from northern KS east across the OH Valley, and along a
confluence zone across western OK. The magnitude of instability will
remain sufficient for pockets of damaging wind potential with any
cluster that can become more organized this evening.

...Great Basin/Northern CA...
Thunderstorms will continue this evening within a weakly unstable
air mass east of an upper-level trough. Steep low-level lapse rates
will result in an isolated damaging wind risk with stronger
updrafts.

...Central/northern Plains...
A couple clusters of strong/severe thunderstorms continue in the
general vicinity of the MT/ND border region, with reports of large
hail over the past couple hours. These storms are located along the
southern periphery of somewhat stronger mid-level flow, and will
moving into a strongly unstable air mass over ND with MLCAPE in the
2000 to 4000 J/kg range. Storms continue to show signs of
organization this evening, and a more concentrated risk for damaging
winds and large hail will exist in association with recently issued
Severe Thunderstorm Watch 543.

..Bunting.. 07/26/2025

$$

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ACUS01 KWNS 260559
SWODY1
SPC AC 260558

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1258 AM CDT Sat Jul 26 2025

Valid 261200Z - 271200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
THE NORTHERN PLAINS...

...SUMMARY...
Severe thunderstorms accompanied by damaging wind gusts will be
possible Saturday afternoon and evening in parts of the northern
Plains. Isolated strong to severe storms will be possible from the
Ohio Valley and lower Great Lakes into the mid-Atlantic region, and
across the central High Plains and much of Montana.

...Synopsis...
An expansive upper-level cyclone over the southeast U.S. will move
little on Saturday, as a broad upper-level trough persists along the
West Coast. A modest belt of stronger mid-level westerlies will
extend across the northern CONUS. A quasi-stationary surface front
will extend east-west across the northern Ohio Valley and southeast
across the mid-Atlantic.

...MT east across the northern/central Plains...
Embedded impulses within the western U.S. upper trough, most notably
now moving northeast across UT, will pivot east across MT and the
northern Plains during the day Saturday. Storms may be in progress
Saturday morning, with additional development along a surface trough
across western SD southward into the central High Plains as
large-scale ascent overspreads the area. Storms over western SD
should evolve upscale over time while moving east/northeast, with an
increasing risk for damaging winds, especially across the Slight
Risk area, where strong instability with eastward extent (MLCAPE
over 3000 J/kg across) will be in place. Deep-layer shear will be
supportive of supercell potential with any semi-discrete storm that
develops, with an attendant risk for large hail.

More isolated storms that develop along the surface trough across
western NE/northeast CO will also have the potential for
strong/severe gusts within a very deep/well-mixed boundary layer.

Isolated stronger storms will also be possible across MT, where weak instability and steep low-level lapse rates will promote some
potential for strong/severe gusts.

...Ohio Valley/Mid-Atlantic Region...
A moist air mass (low-mid 70s surface dew points) will remain in
place south of the quasi-stationary front during the day. Morning
storms will likely be ongoing at 12z Saturday over northern portions
of MO/IL/IN, with some diurnal uptick in coverage/intensity during
the afternoon as a convectively augmented mid-level impulse moves
east across this area. Twenty to 30 kts of deep-layer shear will
result in organized updrafts with a risk for isolated strong wind
gusts and perhaps hail during the afternoon. Isolated storms will
also be possible across the mid-Atlantic, where moderate/strong
mixed-layer instability and modest west-northwest mid-level flow
will support the potential for strong gusts.

..Bunting/Squitieri.. 07/26/2025

$$

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ACUS01 KWNS 261154
SWODY1
SPC AC 261153

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0653 AM CDT Sat Jul 26 2025

Valid 261300Z - 271200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING AND
TONIGHT ACROSS PARTS OF THE DAKOTAS AND NORTHWEST MINNESOTA...

...SUMMARY...
Severe thunderstorms accompanied by damaging wind gusts will be
possible this afternoon through tonight in parts of the northern
Plains. Isolated strong to severe storms will be possible from the
Ohio Valley and lower Great Lakes into the mid-Atlantic region, and
across the central High Plains and much of Montana.

...Northern Plains...
Current water vapor loop shows a well-defined shortwave trough and
associated mid-level speed max over parts of UT. As this feature
tracks northeastward today, large-scale lift and subtle cooling
aloft will overspread parts of northeast WY and central/eastern MT. Northerly/upslope surface winds, combined with strong heating and
moderate CAPE values, will promote the development of scattered
high-based gusty thunderstorms by late afternoon. Storms that move
into western SD will encounter progressively higher CAPE and likely
grow upscale through the evening with a greater risk of organized
severe winds. Latest model guidance suggests some potential for
this activity to persist deep into the night and spread across
eastern ND and parts of northern MN. Damaging winds will remain the
main concern, along with some risk of hail and a tornado or two.

...Midwest into Mid-Atlantic Region...
A large cluster of thunderstorms is ongoing this morning across
parts of IA/IL. The associated outflow boundaries and clouds will
result in an effective baroclinic zone today from northern MO/IL
into southern Lower MI. Along and south of this boundary, hot/humid
conditions will lead to large CAPE values. Scattered afternoon
thunderstorms are expected, with the strongest cells capable of
gusty/damaging winds. This regime will extend eastward into parts
of PA and the Chesapeake Bay area with a few strong afternoon
thunderstorms possible.

..Hart/Grams.. 07/26/2025

$$

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ACUS01 KWNS 261648
SWODY1
SPC AC 261646

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1146 AM CDT Sat Jul 26 2025

Valid 261630Z - 271200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTHERN PLAINS AND MID-ATLANTIC...

...SUMMARY...
Severe thunderstorms accompanied by damaging wind gusts are possible
this afternoon through tonight in parts of the northern
Plains. Isolated strong to severe storms will also be possible from
the Ohio Valley and lower Great Lakes into the mid-Atlantic region,
and across the central High Plains and much of Montana.

...Northern Plains...
Ahead of an upper low over northern California/western Nevada,
midday water vapor imagery reflects a lead shortwave trough moving northeastward over northern Utah/eastern Idaho and western Wyoming.
In this regime, forcing for ascent and gradual cooling aloft will
occur through late today over northern Wyoming and southern/eastern
Montana. Northerly/upslope surface winds, combined with strong
heating and moderate CAPE values, will promote the development of
scattered high-based gusty thunderstorms by late afternoon. This
will initially occur across southern Montana and toward the Big
Horns/northeast Wyoming. Additional high-based storm development is
expected near the surface low and southward-extending surface trough
into the central High Plains. Storms that move into the western
Dakotas will encounter progressively higher CAPE and likely grow
upscale through the evening with a greater risk of organized severe
winds, aside from some continued hail potential. As least some
late-night severe risk will probably persist across North
Dakota/eastern South Dakota into Minnesota.

...Midwest to Mid-Atlantic States/Delmarva...
Multiple clusters of have persisted and/or reinvigorated early today
in a corridor spanning north-central Illinois/northern Indiana, as
well as central Pennsylvania. Moist/humid conditions will exist
south of the convectively reinforced boundary and away from areas of
persistent cloud debris (such as northward into Lower Michigan),
with a reservoir of ample buoyancy contributing to a diurnal
intensification of storms as multiple convectively enhanced
mid-level disturbances interface with the effective front and nearby
warm sector. The strongest storms will be capable of damaging winds,
and a somewhat more favorable corridor for severe thunderstorms/wind
damage appears to exist across the Mid-Atlantic States including south/southeast parts of Pennsylvania toward the Delmarva/Chesapeake
Bay.

..Guyer/Thornton.. 07/26/2025

$$

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ACUS01 KWNS 262000
SWODY1
SPC AC 261959

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0259 PM CDT Sat Jul 26 2025

Valid 262000Z - 271200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN PLAINS AND MID-ATLANTIC...

...SUMMARY...
Severe thunderstorms accompanied by damaging wind gusts are possible
this afternoon through tonight in parts of the northern
Plains. Isolated strong to severe storms will also be possible from
the Ohio Valley and lower Great Lakes into the Mid-Atlantic region,
and across the central High Plains and much of Montana.

...20Z Update...
The forecast remains on track, and only minor changes were made with
this update. The Marginal risk was expanded slightly eastward in
northern MN, where an ongoing cluster of storms (preceding a remnant
MCV) may pose a risk of strong/severe gusts through the afternoon.
For details on the near-term severe risks in the Mid-Atlantic and
Midwest, reference MCDs 1790/1791.

..Weinman.. 07/26/2025

.PREV DISCUSSION... /ISSUED 1146 AM CDT Sat Jul 26 2025/

...Northern Plains...
Ahead of an upper low over northern California/western Nevada,
midday water vapor imagery reflects a lead shortwave trough moving northeastward over northern Utah/eastern Idaho and western Wyoming.
In this regime, forcing for ascent and gradual cooling aloft will
occur through late today over northern Wyoming and southern/eastern
Montana. Northerly/upslope surface winds, combined with strong
heating and moderate CAPE values, will promote the development of
scattered high-based gusty thunderstorms by late afternoon. This
will initially occur across southern Montana and toward the Big
Horns/northeast Wyoming. Additional high-based storm development is
expected near the surface low and southward-extending surface trough
into the central High Plains. Storms that move into the western
Dakotas will encounter progressively higher CAPE and likely grow
upscale through the evening with a greater risk of organized severe
winds, aside from some continued hail potential. As least some
late-night severe risk will probably persist across North
Dakota/eastern South Dakota into Minnesota.

...Midwest to Mid-Atlantic States/Delmarva...
Multiple clusters of have persisted and/or reinvigorated early today
in a corridor spanning north-central Illinois/northern Indiana, as
well as central Pennsylvania. Moist/humid conditions will exist
south of the convectively reinforced boundary and away from areas of
persistent cloud debris (such as northward into Lower Michigan),
with a reservoir of ample buoyancy contributing to a diurnal
intensification of storms as multiple convectively enhanced
mid-level disturbances interface with the effective front and nearby
warm sector. The strongest storms will be capable of damaging winds,
and a somewhat more favorable corridor for severe thunderstorms/wind
damage appears to exist across the Mid-Atlantic States including south/southeast parts of Pennsylvania toward the Delmarva/Chesapeake
Bay.

$$

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ACUS01 KWNS 270104
SWODY1
SPC AC 270102

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0802 PM CDT Sat Jul 26 2025

Valid 270100Z - 271200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTH-CENTRAL U.S....

...SUMMARY...
Severe thunderstorms with damaging wind gusts and hail will be
possible this evening into tonight across parts of the northern
Plains from eastern Montana into the Dakotas and southward to
Nebraska. Isolated damaging wind gusts will also be possible this
evening from parts of the mid Mississippi Valley eastward into the Mid-Atlantic.

...Central and Northern Plains/Northern Rockies...
At mid-levels, a ridge will remain located over the northern Plains
this evening, as a shortwave trough approaches from the southwest.
The shortwave is moving northeastward across the central and
northern Rockies, which is evident on water vapor imagery. Ahead of
this feature, large-scale ascent will overspread a moist airmass
located across the central and northern Plains. Surface dewpoints
within this airmass are mostly from the mid 60s to mid 70s F. This
is contributing to a large pocket of strong instability across the
Dakotas, where MLCAPE is estimated to be in the 3500 to 5500 J/kg
range, according to RAP analysis data. Moderate instability extends
southward into the central Plains. Along the western edge of the
stronger instability, a broken line of thunderstorms is ongoing from
central South Dakota southward into western Nebraska.

Moderate deep-layer shear is analyzed by the RAP over much central
and northern Plains. The stronger flow is a result of upper-level
jets located over far southern Canada and central Nebraska. RAP
forecast soundings from western Nebraska northward into the central
Dakotas generally show 0-6 km shear in the 30 to 40 knot range, with directional shear located in the low to mid-levels. This will be
favorable for supercell development this evening, mainly with cells
that remain semi-discrete. Supercells will likely have an isolated
large hail threat, mainly from central South Dakota into southern
and eastern North Dakota, where the strongest instability is
located. Hailstones greater than 2 inches in diameter will be
possible. In addition, organized line segments with wind-damage
potential are expected.

Further west into parts of the northern High Plains, scattered
thunderstorms are ongoing across central and northeast Montana. As
the shortwave trough moves across the region this evening,
convective coverage is expected to gradually increase. A severe
threat will be possible along an near an axis of moderate
instability, which the RAP currently shows from northwestern North
Dakota into north-central Montana. Very steep low to mid-level lapse
rates would be favorable for damaging wind gusts with the stronger
storms.

....Mid Mississippi and Ohio Valleys/Central
Appalachians/Mid-Atlantic...
A mid-level trough is currently evident on water vapor imagery over
the central and southern Great Lakes. Scattered thunderstorms are
ongoing along the southern edge of this feature from the mid
Mississippi Valley eastward into the central Appalachians. Along
this east-to-west corridor, surface dewpoints are from the 70s into
the lower 80s F. This is contributing to moderate instability, which
is present over most of the region. The unstable environment should
support a marginal wind-damage threat associated with the stronger
multicells this evening.

..Broyles.. 07/27/2025

$$

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ACUS01 KWNS 270554
SWODY1
SPC AC 270552

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1252 AM CDT Sun Jul 27 2025

Valid 271200Z - 281200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE UPPER MISSISSIPPI VALLEY AND WESTERN GREAT LAKES...

...SUMMARY...
Severe thunderstorms will be possible this afternoon and evening
from parts of the upper Mississippi Valley into the western Great
Lakes. Marginally severe storms will also be possible in parts of
the northern Plains, central Appalachians, Mid-Atlantic and eastern
North Carolina.

...Upper Mississippi Valley/Western Great Lakes/Northern Plains...
A shortwave mid-level trough will move eastward into the western
Great Lakes today, as a ridge moves into the northern Plains. At the
surface, a cold front will advance southeastward across the northern
Plains, as a moist and unstable airmass remains over much of the
upper Mississippi Valley. As surface temperatures warm during the
day, thunderstorm development will be likely from the front in
north-central Minnesota eastward to near the tip of Lake Superior.
Convective coverage is forecast to expand in coverage during the
late afternoon as a line segment organizes and moves eastward across
the region.

Ahead of the front, surface dewpoints are expected to be mostly in
the 70s F. This will contribute to the development of strong
instability by afternoon. RAP forecast soundings by 21Z near the
instability axis have MLCAPE in the 2500 to 3500 J/kg range. In
addition, 0-6 km shear is forecast to be around 30 knots, which
should be sufficient for isolated supercell development. Large hail
will be possible with any cell that can become locally intense.
Although supercells will be possible, the most common storm mode
should be multicellular. Some model forecasts suggest that a broken
line segment will develop and move from central and eastern
Minnesota into northern Wisconsin during the mid to late afternoon.
These storms should have wind-damage potential. Additional
development should occur as the low-level jet gradually ramps up,
further to the southwest across parts of far eastern South Dakota
and south-central Minnesota. Isolated large hail and wind damage may
occur with these storms as well.

Further west into parts of northern North Dakota and northern
Montana, moderate instability is expected to develop in some areas
by late afternoon and early evening. Isolated to scattered
thunderstorms may develop across parts of this post-frontal airmass.
RAP forecast soundings by late afternoon from northeast Montana into
northwest North Dakota suggest that moderate deep-layer shear and
steep mid-level lapse rates will be in place. This should support an
isolated severe threat. However, the severe threat should be
marginal, mainly due to limited large-scale ascent.

...Central Appalachians/Mid-Atlantic/Eastern North Carolina...
Northwest mid-level flow will be in place today across much of the
northeastern U.S., as a subtle shortwave trough moves southeastward
across the region. A north-to-south axis of moisture and instability
is forecast to be in place by afternoon from eastern North Carolina
into the Mid-Atlantic. Isolated to scattered thunderstorms are
expected to develop in the afternoon near the instability axis, and
in the higher terrain of the central Appalachians. RAP forecast
soundings late this afternoon near the instability axis have MLCAPE
peaking around 3000 J/kg, with steep low-level lapse rates and
surface dewpoints in the upper 70s F. This environment should
support a marginal wind-damage threat with the stronger multicells.

..Broyles/Squitieri.. 07/27/2025

$$

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ACUS01 KWNS 271139
SWODY1
SPC AC 271138

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0638 AM CDT Sun Jul 27 2025

Valid 271300Z - 281200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
EVENING ACROSS PARTS OF THE UPPER MISSISSIPPI VALLEY INTO THE
WESTERN GREAT LAKES REGION...

...SUMMARY...
Severe thunderstorms will be possible this afternoon and evening
from parts of the upper Mississippi Valley into the western Great
Lakes. Marginally severe storms will also be possible in parts of
the northern Plains, central Appalachians, Mid-Atlantic and eastern
North Carolina.

...Northern MN This Morning...
A persistent bowing MCS is over northern MN headed toward the
Arrowhead region. These storms have produced locally damaging wind
gusts through much of the night, but have shown signs of weakening
on the north end of the bow during the past 1-2 hours. One intense
cells remains on the south end of the bow, headed toward the Hibbing
vicinity. This activity may continue to pose a risk of damaging
winds or hail for awhile this morning.

...Upper MS Valley into western Great Lakes...
A convectively aided shortwave trough is currently tracking across
ND. This feature will move into northern MN this afternoon with an
associated surface cold front sagging into central MN. Steep
mid-level lapse rates and strong heating ahead of the front will
result in a very unstable airmass this afternoon, with MLCAPE values
of 3000-4000 J/kg. A consensus of CAM solutions suggests the
development of a few discrete supercells along the front by mid/late
afternoon. These storms will be capable of very large hail and
perhaps a few tornadoes during the first couple of hours. After
that, upscale growth is likely with damaging winds becoming the main
concern as storms build southeastward across southern MN and into
central WI.

...Mid Atlantic/Central Appalachians...
Scattered afternoon thunderstorms are expected once again today from
parts of PA/WV into VA/NC. Similar to previous days, mid-level
lapse rates will be weak and considerable mid-level moisture will
limit overall severe concerns. However, the strongest cells will be
capable of occasional gusty/damaging winds.

...MT...
Strong heating will occur this afternoon across much of
central/eastern MT, where deep boundary-layer mixing will lead to
inverted-v profiles. Scattered thunderstorms are forecast to
develop along a corridor from southwest into central MT by late
afternoon. These high-based storms may pose a risk of a few
damaging wind gusts.

..Hart/Grams.. 07/27/2025

$$

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ACUS01 KWNS 271702
SWODY1
SPC AC 271700

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1200 PM CDT Sun Jul 27 2025

Valid 271630Z - 281200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS
SOUTHERN/EASTERN MINNESOTA AND FAR EASTERN SOUTH DAKOTA...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
MID-ATLANTIC STATES...

...SUMMARY...
Severe thunderstorms are expected this afternoon and evening across
parts of the Upper Midwest to western Great Lakes. Other severe
storms will also be possible in parts of the northern Plains,
central Appalachians, and Mid-Atlantic.

...Upper Midwest/western Great Lakes including MN/eastern SD...
A convectively enhanced mid-level shortwave trough over
northern/eastern North Dakota will continue generally eastward
toward northern Minnesota, with a modest flattening of the
downstream upper-level ridge into tonight. A modest deepening of the
surface low will occur across eastern South Dakota toward the
southwest Minnesota border vicinity, with intense thunderstorm
development later today generally expected to focus along the southeastward-advancing front, although differential heating and a
convectively aided cluster/possible MCV across northeast South
Dakota at midday may also be factors.

Given the strong buoyancy near/south of the front, and very steep
lapse rates/elevated mixed layer impinging from the west-southwest,
modestly strong wind profiles will be sufficient for intense
supercell development with initial storms, including large hail
potential (higher magnitudes possible especially eastern South
Dakotas and southwest Minnesota) and some tornado risk. Multiple southeastward-moving clusters should evolve this evening with an
increasing likelihood of damaging wind across southern Minnesota
into western/northern Wisconsin. Portions of the region have been
upgraded to an Enhanced Risk.

...Mid-Atlantic/Central Appalachians...
Scattered afternoon thunderstorms will continue to increase
regionally. Similar to previous days, mid-level lapse rates will be
weak and considerable mid-level moisture will keep the overall
potential somewhat limited/isolated. However, the strongest cells
will be capable of occasional gusty/damaging winds, with a somewhat
higher probability of wind damage seemingly existing across eastern
Virginia where buoyancy will be greater.

...Montana...
Strong heating will occur this afternoon across much of
central/eastern Montana, where deep boundary-layer mixing will lead
to inverted-v profiles. Scattered thunderstorms are forecast to
develop along a corridor from southwest into central Montana by late
afternoon. These high-based storms may pose a risk of a few
severe-caliber wind gusts.

..Guyer/Thornton.. 07/27/2025

$$

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ACUS01 KWNS 272002
SWODY1
SPC AC 272000

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 PM CDT Sun Jul 27 2025

Valid 272000Z - 281200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS
SOUTHERN/CENTRAL MINNESOTA AND FAR EASTERN SOUTH DAKOTA...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
MID-ATLANTIC STATES...

...SUMMARY...
Severe thunderstorms are expected this afternoon and evening across
parts of the Upper Midwest to western Great Lakes. Other severe
storms are also possible in parts of the northern Plains, central
Appalachians, and Mid-Atlantic.

...20Z Update...
Both the Slight and Enhanced risks were expanded slightly
west-southwestward in eastern SD with this update. Here, the latest
guidance has come into relatively good agreement, depicting
convective development ahead of a gradually evolving surface low
into this evening. Very steep deep-layer lapse rates/extreme
surface-based buoyancy and 40-50 kt of effective shear will promote supercells/organized clusters capable of producing large hail and
severe wind gusts.

Farther east, the Marginal risk was expanded southward across
southeastern NC into northern SC. Strong heating/destabilization
will promote damaging wind gusts with any small thunderstorm
clusters that evolve.

..Weinman.. 07/27/2025

.PREV DISCUSSION... /ISSUED 1200 PM CDT Sun Jul 27 2025/

...Upper Midwest/western Great Lakes including MN/eastern SD...
A convectively enhanced mid-level shortwave trough over
northern/eastern North Dakota will continue generally eastward
toward northern Minnesota, with a modest flattening of the
downstream upper-level ridge into tonight. A modest deepening of the
surface low will occur across eastern South Dakota toward the
southwest Minnesota border vicinity, with intense thunderstorm
development later today generally expected to focus along the southeastward-advancing front, although differential heating and a
convectively aided cluster/possible MCV across northeast South
Dakota at midday may also be factors.

Given the strong buoyancy near/south of the front, and very steep
lapse rates/elevated mixed layer impinging from the west-southwest,
modestly strong wind profiles will be sufficient for intense
supercell development with initial storms, including large hail
potential (higher magnitudes possible especially eastern South
Dakotas and southwest Minnesota) and some tornado risk. Multiple southeastward-moving clusters should evolve this evening with an
increasing likelihood of damaging wind across southern Minnesota
into western/northern Wisconsin. Portions of the region have been
upgraded to an Enhanced Risk.

...Mid-Atlantic/Central Appalachians...
Scattered afternoon thunderstorms will continue to increase
regionally. Similar to previous days, mid-level lapse rates will be
weak and considerable mid-level moisture will keep the overall
potential somewhat limited/isolated. However, the strongest cells
will be capable of occasional gusty/damaging winds, with a somewhat
higher probability of wind damage seemingly existing across eastern
Virginia where buoyancy will be greater.

...Montana...
Strong heating will occur this afternoon across much of
central/eastern Montana, where deep boundary-layer mixing will lead
to inverted-v profiles. Scattered thunderstorms are forecast to
develop along a corridor from southwest into central Montana by late
afternoon. These high-based storms may pose a risk of a few
severe-caliber wind gusts.

$$

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ACUS01 KWNS 280102
SWODY1
SPC AC 280100

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0800 PM CDT Sun Jul 27 2025

Valid 280100Z - 281200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR FAR EASTERN
SOUTH DAKOTA INTO CENTRAL AND SOUTHERN MINNESOTA...

...SUMMARY...
Severe-wind producing storms remain a threat through tonight across
the Upper Mississippi Valley, with more isolated strong storms
possible over the northern Plains. Strong wind gusts will remain a
concern for eastern North Carolina for a few more hours.

...Synopsis and Discussion...
Surface ridging persists across the central and eastern CONUS, with
multiple mid-level perturbations traversing the ridge and supporting
episodic strong to severe thunderstorms from the northern Plains to
the East Coast.

Across the Upper MS Valley, a loosely organized MCS with intense
embedded multicells and supercells, with a history of all severe
hazards, continues to sag southward. The MCS line orientation
roughly aligns with the mean wind and deep-layer shear vector, which
appears to be the main inhibiting factor for a higher-end severe
threat. Nonetheless, given 4000-6000 J/kg MLCAPE preceding these
storms, additional severe gusts appear likely, and a couple
tornadoes cannot be ruled out wherever mesovortices or embedded
supercell mesocyclones can materialize. To the southwest, along a
diffuse frontal boundary, isolated storms continue to percolate in
intensity. It is not clear how long these storms will persist. The
current thinking is that these storms may pose an isolated threat
for all severe hazards for at least a couple more hours, before
nocturnal cooling and MLCINH increase.

More isolated storms may persist from central MT or southwestern
Manitoba as they approach the northern Plains. Any storms that do
sustain themselves should be isolated, though the presence of strong instability and 40+ kts of effective bulk shear suggest that severe
hail/wind could accompany any storm that can mature. It is possible
that an MCS could evolve over eastern MT into western ND a couple of
hours before the 12Z timeframe, which might involve a higher
concentration of severe winds. However, overall confidence in MCS
organization before 12Z is low at this time.

Multicells sagging southward across NC should wane in intensity
tonight. However, for at least a couple more hours, enough
instability may be in place to support a damaging gust or two.

..Squitieri.. 07/28/2025

$$

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ACUS01 KWNS 280557
SWODY1
SPC AC 280555

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1255 AM CDT Mon Jul 28 2025

Valid 281200Z - 291200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
EASTERN SOUTH DAKOTA INTO FAR WESTERN MINNESOTA...

...SUMMARY...
A derecho is likely across portions of the northern Plains, with
several gusts expected to exceed 75 mph. A few line-embedded
tornadoes and instances of severe hail may also occur. Isolated to
potentially scattered storms may product severe wind and hail over
portions of Montana.

...Synopsis...
An upper ridge will dominate the upper-pattern across the CONUS
today, with multiple mid-level perturbations poised to crest the
upper ridge through the period. The first impulse is expected to
trigger a cluster of thunderstorms that will rapidly grow upscale
into an intense MCS and produce a widespread severe wind swath with
embedded 75+ mph gusts across portions of the northern Plains. A
second mid-level impulse will traverse the northern Rockies, amid
favorable wind shear and buoyancy, to support a severe threat.

...Northern Plains...
Multicellular convection is expected to initiate and grow upscale
into an MCS across the northern High Plains at some point in the
morning to early afternoon time frame. As the MCS propagates
eastward across the Dakotas, and matures with a deepening cold pool,
it will encounter an elongated corridor of extreme buoyancy, where
mid 70s surface dewpoints beneath 9+ C/km mid-level lapse rates will
boost MLCAPE to well over 5000 J/kg. Guidance consensus shows 50+
kts of effective bulk shear coinciding this extreme instability
axis, with some hodographs depicting modest low-level
size/curvature. This buoyancy/shear profile should support an
intense MCS capable of producing a derecho, with widespread severe
winds expected, and several 75+ mph gusts likely. Given anticipated
strong low-level shear (e.g. 300+ m2/s2 effective SRH), a few
tornadoes may occur with the stronger, more persistent leading-line system-scale mesovortices.

Some CAM guidance differs slightly on the position of the
derecho-producing MCS, including the possibility of a secondary bow
echo developing closer to the SD/NE border. The track of the parent
bow echo will be largely dependent on where the baroclinic boundary
from an MCS (ongoing along the MN/IA border) sets up with daytime
airmass modification. Therefore, some adjustments in the position of probabilities may be needed in future outlooks. Regardless of the aforementioned details, a higher-end severe wind event should unfold
across the northern Plains, especially over central into eastern SD.

...Montana...
Scattered thunderstorms will develop by afternoon peak heating in a post-frontal airmass. Despite a drier low-level airmass, 8-9 C/km
troposheric lapse rates amid straight and elongated hodographs
(effective bulk/speed shear near 50 kts) will support multicells and
supercell structures capable of severe wind and hail.

..Squitieri/Dean.. 07/28/2025

$$

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ACUS01 KWNS 281227
SWODY1
SPC AC 281225

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0725 AM CDT Mon Jul 28 2025

Valid 281300Z - 291200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
AND TONIGHT OVER PORTIONS OF EASTERN SOUTH DAKOTA AND SOUTHWESTERN MINNESOTA....

...SUMMARY...
Numerous severe thunderstorms capable of widespread damaging winds
are likely across portions of the northern Plains, with several
gusts expected to exceed 75 mph. A few line-embedded tornadoes and
instances of severe hail may also occur. Widely scattered storms may
produce severe wind and hail over portions of Montana.

...Northern Plains...
A convectively active afternoon and evening is expected across parts
of the Dakotas/MN/IA/WI, where numerous intense thunderstorms are
expected. An overnight MCS has temporarily stabilized/modified the
air mass across much of MN/IA. A consensus of model guidance
appears to have handled this scenario well, and depicts rapid return
of low-level moisture and heating across this region by
mid-afternoon. Meanwhile upstream in eastern MT and western ND/SD,
a subtle shortwave trough will top the ridge and spread large scale
forcing into the region, leading to scattered thunderstorm
development. Very steep mid-level lapse rates are in place across
ND/SD, where easterly low-level winds and evapo-transpiration will
help surface dewpoints to rise to near 70F. Forecast soundings show
extreme instability will develop (MLCAPE values over 6000 J/kg)
aiding in rapid intensification of supercells across central SD.
Large hail, damaging winds, and a few tornadoes may occur with this
early activity.

The most likely scenario for evening convective activity continues
to be for an organized and fast-moving linear MCS to develop and
race eastward across eastern SD into parts of MN/IA. One or more
corridors of widespread/significant wind damage are expected,
possibly achieving derecho criteria. Have extended the ENH/SLGT
risk areas a little farther east into parts of MN/IA/WI, where a few
overnight CAM solutions suggest the bowing complex persists before
weakening late tonight.

...Central MT...
Easterly low-level winds across MT will advect moisture westward
into the mountains, where scattered thunderstorm development is
expected by late afternoon. These storms will spread into central
MT during the evening, with sufficient CAPE and vertical shear for a
risk of large hail and damaging wind gusts.

..Hart/Grams.. 07/28/2025

$$

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ACUS01 KWNS 281631
SWODY1
SPC AC 281630

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1130 AM CDT Mon Jul 28 2025

Valid 281630Z - 291200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
INTO TONIGHT FROM EASTERN SOUTH DAKOTA ACROSS SOUTHERN MINNESOTA AND
NORTHERN IOWA...

...SUMMARY...
Severe storm clusters are expected to form this afternoon in South
Dakota and then spread southeastward into Minnesota and Iowa through
tonight. Swaths of damaging winds, potentially 75-90 mph, a few
tornadoes and isolated large hail will all be possible.

...Dakotas to MN/IA through tonight...
Around the northern periphery of a midlevel high covering the
southern Plains and Southeast, a series of embedded speed maxima
will progress from MT across the Dakotas to MN through early
Tuesday. Elevated convection is ongoing in association with two
such speed maxima - one over ND and another moving eastward over
eastern MT. At the surface, a lee cyclone is present near the SD/NE
border, and a baroclinic zone arcs into northeast SD and then
southeastward across southwest MN into northern IA. A prior outflow
boundary (from dissipated overnight convection) will become more
diffuse with time as a result of strong surface heating across
IA/NE/SD within the old cold pool.

The elevated convection across southern ND, and moving from MT into
southwest ND, could persist in the post-frontal environment with
weak warm advection atop the frontal surface. Steep midlevel lapse
rates and 40-50 kt midlevel flow suggests a continued threat for
occasional severe outflow gusts and isolated large hail. The more
substantial severe-storm threat is expected to evolve farther
southeast by mid-late afternoon along the baroclinic zone in SD, to
the northeast of the lee cyclone. Strong surface heating, continued
moisture advection and evapotranspiration will lead to the
development of strong-extreme buoyancy (3000-4500+ J/kg MLCAPE)
beneath an elevated mixed layer with 8.5-9 C/km midlevel lapse
rates. Storms that form in SD are then expected to congeal into a
cluster or two that will subsequently spread east-southeastward
along the more northwest-southeast oriented baroclinic zone now
noted in visible imagery and surface observations from southwest MN
into northern IA. The thermodynamic environment will favor both
intense updrafts and downdrafts, while deep-layer vertical shear
will be sufficient for an organized/bowing MCS. Thus, there will be
the potential for swaths of significant-severe outflow (75-90 mph),
as well as isolated large hail and a few tornadoes (either with
initially discrete supercells or with embedded circulations with
bowing segments).

...Central MT this afternoon through early tonight...
An embedded speed max will crest the ridge and move from ID to
southwest MT this afternoon/evening. Residual boundary-layer
dewpoints in the mid-upper 50s in the post-frontal environment,
along with surface heating and the north edge of the steeper
midlevel lapse rates will favor scattered thunderstorm development
by early-mid afternoon (near and just northeast of the higher
terrain southwest into central MT). MLCAPE of 1500-2000 J/kg,
effective bulk shear in excess of 40 kt and seasonably cool midlevel temperatures suggest the potential for initial supercells with large
hail (1-2.5 inches in diameter), and also the potential for upscale
growth into a cluster with the attendant threat for wind damage.

..Thompson/Thornton.. 07/28/2025

$$

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ACUS01 KWNS 282002
SWODY1
SPC AC 282000

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 PM CDT Mon Jul 28 2025

Valid 282000Z - 291200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
INTO TONIGHT FROM EASTERN SOUTH DAKOTA ACROSS SOUTHERN MINNESOTA AND
NORTHERN IOWA...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
CENTRAL MONTANA...

...SUMMARY...
Severe storm clusters are expected to form this afternoon in South
Dakota and then spread southeastward into Minnesota and Iowa through
tonight. Swaths of damaging winds, potentially 75-90 mph, a few
tornadoes and isolated large hail will all be possible.

...20Z Update...
The primary change with this update was removing the Slight risk
area across parts of the northern High Plains -- where the severe
risk has decreased behind an earlier cluster of storms. Elsewhere,
the previous forecast thinking remains the same. Thunderstorms are
evolving across the higher terrain in western MT, and will track
eastward into an increasingly moist/unstable air mass this
afternoon. Reference Severe Thunderstorm Watch 551 and MCD 1823 for
details.

Farther east, thunderstorms are developing along a baroclinic zone
extending across SD. These storms will pose a risk of severe
downbursts as they develop into a hot/deeply mixed air mass in
south-central SD and north-central NE this afternoon (see MCD 1824).
This activity, and potentially new development along the baroclinic
zone, should eventually spread eastward into eastern SD -- where intensification into one or more organized/intense clusters is still
expected into tonight.

..Weinman.. 07/28/2025

.PREV DISCUSSION... /ISSUED 1130 AM CDT Mon Jul 28 2025/

...Dakotas to MN/IA through tonight...
Around the northern periphery of a midlevel high covering the
southern Plains and Southeast, a series of embedded speed maxima
will progress from MT across the Dakotas to MN through early
Tuesday. Elevated convection is ongoing in association with two
such speed maxima - one over ND and another moving eastward over
eastern MT. At the surface, a lee cyclone is present near the SD/NE
border, and a baroclinic zone arcs into northeast SD and then
southeastward across southwest MN into northern IA. A prior outflow
boundary (from dissipated overnight convection) will become more
diffuse with time as a result of strong surface heating across
IA/NE/SD within the old cold pool.

The elevated convection across southern ND, and moving from MT into
southwest ND, could persist in the post-frontal environment with
weak warm advection atop the frontal surface. Steep midlevel lapse
rates and 40-50 kt midlevel flow suggests a continued threat for
occasional severe outflow gusts and isolated large hail. The more
substantial severe-storm threat is expected to evolve farther
southeast by mid-late afternoon along the baroclinic zone in SD, to
the northeast of the lee cyclone. Strong surface heating, continued
moisture advection and evapotranspiration will lead to the
development of strong-extreme buoyancy (3000-4500+ J/kg MLCAPE)
beneath an elevated mixed layer with 8.5-9 C/km midlevel lapse
rates. Storms that form in SD are then expected to congeal into a
cluster or two that will subsequently spread east-southeastward
along the more northwest-southeast oriented baroclinic zone now
noted in visible imagery and surface observations from southwest MN
into northern IA. The thermodynamic environment will favor both
intense updrafts and downdrafts, while deep-layer vertical shear
will be sufficient for an organized/bowing MCS. Thus, there will be
the potential for swaths of significant-severe outflow (75-90 mph),
as well as isolated large hail and a few tornadoes (either with
initially discrete supercells or with embedded circulations with
bowing segments).

...Central MT this afternoon through early tonight...
An embedded speed max will crest the ridge and move from ID to
southwest MT this afternoon/evening. Residual boundary-layer
dewpoints in the mid-upper 50s in the post-frontal environment,
along with surface heating and the north edge of the steeper
midlevel lapse rates will favor scattered thunderstorm development
by early-mid afternoon (near and just northeast of the higher
terrain southwest into central MT). MLCAPE of 1500-2000 J/kg,
effective bulk shear in excess of 40 kt and seasonably cool midlevel temperatures suggest the potential for initial supercells with large
hail (1-2.5 inches in diameter), and also the potential for upscale
growth into a cluster with the attendant threat for wind damage.

$$

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ACUS01 KWNS 290037
SWODY1
SPC AC 290036

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0736 PM CDT Mon Jul 28 2025

Valid 290100Z - 291200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FROM SOUTHEAST
SOUTH DAKOTA INTO SOUTHERN MINNESOTA AND NORTHERN IOWA...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER MUCH OF
CENTRAL MONTANA...

...SUMMARY...
A corridor of significant damaging winds remains possible from
southeast South Dakota and into southern Minnesota and northern
Iowa. Sporadic large hail or an isolated tornado may also occur.

...SD...MN...NE...IA...
Scattered severe storms persist this evening from far northern NE
across eastern SD and into west-central MN. A complex mixture of
storm modes currently exists, but latest trends indicate a
larger-scale damaging wind risk may be evolving.

Previously tornadic supercells over SD are now moving generally
eastward along the SD/NE border, with additional cells filling in
into northeast SD and western MN. Of particular concern are storms
west through southwest of the Sioux Falls area. If these can congeal
further with a more consolidated outflow, the very moist and
unstable air mass may support significant damaging gusts downstream
into northern IA and southern MN later this evening/tonight.

The line of storms currently over west-central MN is also becoming
better organized, with strong deep-layer mean winds across this
region. This may counteract the lesser instability values over this
area and toward the MS River later this evening.

Finally, it is unclear how far south the southern fringe of the
severe wind risk may be. The OAX 00Z sounding remains very unstable,
with a surmountable warm nose given an organized convective system.
As such, severe probabilities were nudged a bit farther south.

...MT...
A complex of thunderstorms is moving east across central MT, with
areas of severe hail and wind indicated on radar. Moderate
deep-layer shear and steep lapse rates aloft are allowing for a few longer-lived cells with hail. Capping will be slow to materialize
this evening given the moist low-level air mass, and as such a few
severe storms may be possible into east-central MT.

..Jewell.. 07/29/2025

$$

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ACUS01 KWNS 290612
SWODY1
SPC AC 290611

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0111 AM CDT Tue Jul 29 2025

Valid 291200Z - 301200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM SOUTHERN
MONTANA ACROSS EASTERN WYOMING...NEBRASKA...AND INTO WESTERN IOWA...

...SUMMARY...
Severe thunderstorms are expected from southern Montana into the
central High Plains, and across much of Nebraska and western Iowa.
Areas of damaging winds will be possible, with hail most likely over
western areas.

...Much of NE into IA...
A cold front is likely to extend from northeast Co into northern NE
and IA during the afternoon, while low pressure develops over
western KS. Winds aloft will be relatively weak at these latitudes,
only averaging near 15-20 kt. Winds below 500 mb will also be
relatively weak, except for within the deeply mixed boundary layer
with gusty south winds.

Indications are that thunderstorms will develop by late afternoon
across eastern CO and western NE, with increasing coverage and vigor
near the stalled front across NE and into northern IA. Models
indicate numerous storms during the evening, with a general eastward propagation. Given such weak winds below 500 mb, it appears
widespread and potentially shorter lived convection will be
possible. However, an eventual aggregation into an MCS is expected,
which could yield greater overall coverage of strong to severe
gusts. Isolated significant gusts cannot be ruled out as storms move
into the strongly heated air mass/deeply mixed boundary layer.

...MT into WY...
High pressure will exist over southern Canada with northeast surface
winds across much of the northern Plains. Dewpoints in the 50s to
near 60 F will remain with in this air mass from eastern MT into WY,
and daytime heating will yield MUCAPE over 2000 J/kg by afternoon.
Cool temperatures aloft will exist in the mid and upper levels,
along with 20-30 kt westerlies. Storms will form over the higher
terrain during the late afternoon, aided by upslope flow. Given the
backed low-level wind fields, sufficient shear will favor large
hail, perhaps into the 1.75 to 2.00" range in the strongest cells.
Locally damaging gusts will also be likely.

..Jewell/Squitieri.. 07/29/2025

$$

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ACUS01 KWNS 291204
SWODY1
SPC AC 291203

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0703 AM CDT Tue Jul 29 2025

Valid 291300Z - 301200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
INTO TONIGHT FROM PARTS OF THE NORTHERN HIGH PLAINS INTO THE CENTRAL
PLAINS....

...SUMMARY...
Severe thunderstorms are expected from southern Montana into the
central High Plains, and across much of Nebraska and western Iowa.
Areas of damaging winds will be possible, with hail most likely over
western areas.

...CO/NE/IA...
Morning water vapor loops show a large ridge over the central US,
with a plume of ample mid-level moisture moving northward across the
southern Rockies. Northeasterly surface winds across northeast CO
will help moisten/destabilize the region, leading to thunderstorms
off the foothills of central CO by mid-afternoon. These storms will
be in a region of moderate CAPE, but rather weak vertical shear and
winds aloft. Clusters of storms capable of small hail and gusty
winds will build eastward through the afternoon into a progressively
more moist/unstable airmass, and may eventually intensify into an
organized MCS across NE/western IA. This activity may persist well
into the night with a risk of locally damaging wind gusts.

...WY/MT...
Multiple weak shortwave troughs are tracking northward across the
Great Basin today toward the northern Rockies. This will lead to
scattered afternoon thunderstorms over the mountains of southwest MT
and northern WY. Surface dewpoints in the 50s along with strong
daytime heating will result in considerable CAPE, along with
sufficient westerly winds aloft for some convective organization.
Initial storms over the higher terrain will pose some risk of hail
and gusty winds. As the activity builds eastward into the plains, a
greater risk for large hail and severe winds will likely develop
through the evening.

..Hart/Grams.. 07/29/2025

$$

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ACUS01 KWNS 291633
SWODY1
SPC AC 291632

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1132 AM CDT Tue Jul 29 2025

Valid 291630Z - 301200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
INTO TONIGHT FROM PARTS OF THE NORTHERN HIGH PLAINS INTO THE CENTRAL
PLAINS...

...SUMMARY...
Severe thunderstorms are expected from southern Montana into the
central High Plains, and across much of Nebraska and western Iowa.
Areas of severe gusts will be possible, with hail most likely over
western areas.

...CO/NE/IA...
Surface analysis indicates a frontal zone draped from IA
west-southwestward into the central High Plains. Moist conditions
either side of the boundary and ample heating will promote a very to
extremely unstable airmass as temperatures continue to warm through
the mid afternoon. Initial storms are progged over the central High
Plains with perhaps other activity continuing across the mid MS
Valley through the afternoon. Hail/wind will be possible with the
earlier storms, but a gradual increase in storm coverage is forecast
this evening into the overnight near/north of the boundary. Severe
gusts will tend to be the main severe hazard tonight.

...WY/MT...
Water-vapor imagery late this morning shows a prominent shortwave
trough over the northern Great Basin moving into eastern ID/WY this
afternoon. A moist (dewpoints in the 50s to lower 60s) and
destabilizing boundary layer near/northeast of a residual frontal
zone, coupled with orographic and large-scale ascent, will lead to
scattered afternoon thunderstorms. Easterly flow beneath moderate
westerlies will yield effective shear supporting organized storms,
including a few supercells and organized clusters. Hail/wind will
be the primary severe hazards before a tendency for upscale growth
into linear clusters during the evening.

...Southeast OR...
A mid-level trough over the Sierra into the northern Great Basin,
embedded within larger-scale trough over the West Coast, will move
northward through this evening across the northern Great Basin into
southern OR/ID. Scattered high-based thunderstorms will probably
focus along the leading edge of ascent as low to mid tropospheric
lapse rates exceed 9 deg C/km. A relatively dry sub-cloud layer
will promote evaporatively cooled downdrafts capable of isolated
severe gusts (60-70 mph) with the stronger cores/clusters, mainly
during the 22-04 UTC period.

..Smith/Halbert.. 07/29/2025

$$

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ACUS01 KWNS 291955
SWODY1
SPC AC 291954

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0254 PM CDT Tue Jul 29 2025

Valid 292000Z - 301200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THERE IS A SLIGHT
RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO TONIGHT FROM PARTS
OF THE NORTHERN HIGH PLAINS INTO THE CENTRAL PLAINS...

...SUMMARY...
Severe thunderstorms are expected from southern Montana into the
central High Plains, and across much of Nebraska and western Iowa.
Areas of severe gusts will be possible, with hail most likely over
western areas.

...20z Update...
The forecast largely remains on track with the early stages of
convective initiation underway across portions of north/northwest WY
and along the central High Plains per recent satellite imagery and
regional radar composites. The primary change for this forecast
update was the introduction of significant hail/wind areas to
portions of the northern Rockies. Latest GOES imagery shows
convection beginning to develop across northern WY/southern MT ahead
of a shortwave trough over the Great Basin. Regional 18z soundings
continue to sample steep (8-9 C/km) mid-level lapse rates, and GOES
imagery suggests 30-40 knot mid-level winds are overspreading the
region. As such, a favorable environment for a few supercells
appears to be in place and should support the potential for very
large hail. This activity should grow upscale through late evening
with the potential for a few significant (75+ mph) wind gusts. See
MCD #1833 for additional short-term details.

Across the Plains, the significant wind risk area has been adjusted
to better align with recent convective development along a
stationary boundary draped from southwest to northeast across NE and
where boundary-layer mixing appears to be deepest (based on observed
dewpoint depressions), which should favor stronger downdrafts and a
higher potential for significant gusts. See MCD #1834 for additional
short-term details.

..Moore.. 07/29/2025

.PREV DISCUSSION... /ISSUED 1132 AM CDT Tue Jul 29 2025/

...CO/NE/IA...
Surface analysis indicates a frontal zone draped from IA
west-southwestward into the central High Plains. Moist conditions
either side of the boundary and ample heating will promote a very to
extremely unstable airmass as temperatures continue to warm through
the mid afternoon. Initial storms are progged over the central High
Plains with perhaps other activity continuing across the mid MS
Valley through the afternoon. Hail/wind will be possible with the
earlier storms, but a gradual increase in storm coverage is forecast
this evening into the overnight near/north of the boundary. Severe
gusts will tend to be the main severe hazard tonight.

...WY/MT...
Water-vapor imagery late this morning shows a prominent shortwave
trough over the northern Great Basin moving into eastern ID/WY this
afternoon. A moist (dewpoints in the 50s to lower 60s) and
destabilizing boundary layer near/northeast of a residual frontal
zone, coupled with orographic and large-scale ascent, will lead to
scattered afternoon thunderstorms. Easterly flow beneath moderate
westerlies will yield effective shear supporting organized storms,
including a few supercells and organized clusters. Hail/wind will
be the primary severe hazards before a tendency for upscale growth
into linear clusters during the evening.

...Southeast OR...
A mid-level trough over the Sierra into the northern Great Basin,
embedded within larger-scale trough over the West Coast, will move
northward through this evening across the northern Great Basin into
southern OR/ID. Scattered high-based thunderstorms will probably
focus along the leading edge of ascent as low to mid tropospheric
lapse rates exceed 9 deg C/km. A relatively dry sub-cloud layer
will promote evaporatively cooled downdrafts capable of isolated
severe gusts (60-70 mph) with the stronger cores/clusters, mainly
during the 22-04 UTC period.

$$

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ACUS01 KWNS 300043
SWODY1
SPC AC 300042

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0742 PM CDT Tue Jul 29 2025

Valid 300100Z - 301200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE NORTHERN
HIGH PLAINS INTO PARTS OF THE CORN BELT...

...SUMMARY...
Severe thunderstorms remain possible this evening from southeast
Montana ad eastern Wyoming across parts of South Dakota, Nebraska,
and Iowa.

...Northern High Plains...
Widely scattered cells producing severe hail persist this evening in
the post frontal/upslope regime from southeast MT into eastern WY. A
narrow instability plume ahead of these storms may support a
continued hail risk approaching the Black Hills later this evening.
For more information see mesoscale discussion 1838.

...NE into western IA...
Clusters of storms continue to evolve within a weak shear
environment from northwest KS across central NE and into southeast
SD where more substantial outflow is present. The primary deep-layer
theta-e axis remains across the NE into IA zone, and this strongly
unstable and moist air mass will continue to support swaths of
damaging winds and marginal hail. The weak wind fields below 500 mb
will continue to be a limiting factor to overall severity.

..Jewell.. 07/30/2025

$$

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ACUS01 KWNS 300540
SWODY1
SPC AC 300538

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1238 AM CDT Wed Jul 30 2025

Valid 301200Z - 311200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
THE NORTHEAST...THE NORTHERN TO CENTRAL HIGH PLAINS...AND LOWER MID
MISSISSIPPI VALLEY TO MIDWEST AREA...

...SUMMARY...
Widely scattered strong to severe thunderstorms are possible from
the mid Missouri/Mississippi Valley, over parts of the
Mid-Atlantic/Northeast region, and from southern Montana across
Wyoming and Colorado.

...Synopsis...
A large upper low/trough will exist over eastern Canada, with a belt
of strong upper-level winds across the Northeast. Meanwhile, upper
highs will exist over FL and AZ/NM, with a weak upper trough
affecting the Great Basin into the Pacific Northwest.

At the surface, a large area of high pressure will stretch from the
northern Plains across the Great Lakes, with a leading cold front
pushing into northern Mid Atlantic region during the afternoon. The
western extension of this front, south of the surface high, will
stretch across parts of the Midwest and into the central Plains
through 00Z.

Ahead/south of this front, a moist air mass will remain in place
with 60s to 70s F dewpoints, with daytime heating aiding
destabilization and scattered storm development.

...Northeast...
A narrow plume of modest instability will develop with daytime
heating ahead of the cold front. A midlevel temperature gradient
will exist across the region, with 500 mb temperatures from -10 C
southern areas and approaching -15 C over northern ME. Deep-layer
shear near 50 kt will result in lengthy straight hodographs, which
will favor cellular storm mode. Hail appears to be the primary issue
with the strongest cells, but overall severe coverage looks to be
isolated.

...Southern MT...WY...CO...
Minimal upper ridging will remain over the Rockies ahead of the
western trough, and midlevel temperatures will be rather cool.
Daytime heating combined with 50s F dewpoints into MT, central WY
and toward the Front Range will support scattered strong to locally
severe storms during the afternoon over the higher terrain. Both
marginal hail and severe gusts will be possible, especially over WY.


...Mid MO/MS Valley...
Storms are forecast to be ongoing early this morning from eastern NE
into IA. Veering winds around 850 mb as well as the southward
sinking front with outflow should allow for a continuation of this
activity into IL and eventually MO, where clusters of storms may
produce locally strong to damaging gusts. Shear will be weak, and
therefore the overall threat most likely localized. Some of this
activity may reach into IN by evening.

..Jewell/Squitieri.. 07/30/2025

$$

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ACUS01 KWNS 301216
SWODY1
SPC AC 301215

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0715 AM CDT Wed Jul 30 2025

Valid 301300Z - 311200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
THE NORTHEAST...THE NORTHERN TO CENTRAL HIGH PLAINS...AND LOWER MID
MISSISSIPPI VALLEY TO MIDWEST AREA...

...SUMMARY...
Widely scattered strong to severe thunderstorms are possible from
the Lower Missouri/Mid Mississippi Valleys, over parts of the Mid-Atlantic/Northeast region, and from southern Montana across
Wyoming and Colorado.

...Mid MS Valley...
A long-lived linear MCS is tracking eastward across parts of IA/MO
this morning. This activity is expected to persist through much of
the day and affect parts of IL/IN/OH/Lower MI. Ample low-level
moisture is present across this region, and the convectively-aided
shortwave trough associated with the MCS will provide sufficient
vertical shear for some concern for a few severe wind gusts through
the day. An upgrade to SLGT risk was considered for this region,
but given the expansive shield of clouds ahead of the storms,
coupled with a consensus of model guidance showing limited intensity
to the storms, chose to maintain MRGL risk and re-evaluate at 1630z.


...High Plains...
Similar to yesterday, ample mid-level moisture is present across the
central Rockies into WY. This will lead to scattered thunderstorms
by early afternoon from parts of central CO into central/western WY.
Winds aloft are slightly stronger than yesterday, which will
provide an uptick in vertical shear and convective organization.
Hail and gusty winds will be possible with storms that form over the
higher terrain and spread into the adjacent plains through the
afternoon and early evening.

...Northeast...
A weak surface cold front will sag southward across New England and
parts of NY/PA today, with a moist and moderately unstable air mass
expected ahead of the boundary. Low-level convergence along the
front will be weak, with only widely scattered thunderstorm coverage
expected. However, cool temperatures aloft and steep low-level
lapse rates will promote a risk of gusty/damaging winds and at least
small hail in the storms that form this afternoon.

..Hart/Grams.. 07/30/2025

$$

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ACUS01 KWNS 301632
SWODY1
SPC AC 301630

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1130 AM CDT Wed Jul 30 2025

Valid 301630Z - 311200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
THE NORTHEAST...THE NORTHERN TO CENTRAL HIGH PLAINS...AND KANSAS
INTO THE SOUTHERN GREAT LAKES...

...SUMMARY...
Widely scattered strong to severe thunderstorms are possible from
Kansas into the Mid Mississippi Valley and southern Great Lakes, and
over parts of the Mid-Atlantic/Northeast region, and from southern
Montana across Wyoming and Colorado.

...Mid MS Valley...
Radar/visible-satellite mosaic shows a sub-severe squall line from
near Saint Louis into northern IL moving slowly east-southeastward
across the Corn Belt. Some rejuvenation of storm intensity may
occur with storms along the leading edge of the cold pool as it
moves into eastern IL/IN/OH/Lower MI. Isolated 50-65 mph gusts
capable of wind damage may occur with this activity. Farther west,
a weak mid-level shortwave disturbance is implied in satellite
imagery near the KS/NE border, and a surface low was analyzed over south-central KS along the trailing frontal zone. These features
may aid in focusing scattered storms this afternoon over parts of
central and eastern KS. The boundary layer continues to
heat/destabilize with surface dewpoints ranging from the upper 60s
to mid 70s across central and eastern KS. Isolated severe gusts and
possibly large hail may accompany the stronger storms late this
afternoon into the evening.

...High Plains...
A seasonably moist airmass resides across the central and northern
Rockies and adjacent plains late this morning. Water-vapor imagery
and earlier radar mosaic data implied a weak disturbance cresting a
ridge over the northern WY/southern MT border. Influence from this
disturbance and westerly 40-50 kt high-level flow will support some
storm organization potential. Forecast soundings across central WY
show 1000-1500 J/kg MLCAPE and effective shear 30-40 kt. This may
support a couple of supercells capable of threat for large hail.
Upscale growth into a linear cluster may evolve in central WY late
this afternoon into the early evening, coincident with a risk for
severe gusts. Farther south, storm coverage may be locally greater
across the Front Range and I-25 corridor from Denver to Pueblo.
Isolated to widely scattered wind/hail seem likely with the stronger cores/outflow. Elsewhere, it appears an isolated risk for severe
will encompass the larger general area from southern MT into eastern
CO.

...Northeast...
A weak surface cold front will sag southward into a moist/adequately
unstable airmass across New England and parts of NY/PA this
afternoon into the evening. Low-level convergence along the front
will be weak and will limit overall storm coverage. However, cool
temperatures aloft and steep low-level lapse rates will promote a
risk of gusty/damaging winds and at least small hail in the storms
that form this afternoon. For short-term details regarding the
severe risk in portions of northern New England, refer to MCD #1846.

..Smith/Halbert.. 07/30/2025

$$

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ACUS01 KWNS 301946
SWODY1
SPC AC 301945

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0245 PM CDT Wed Jul 30 2025

Valid 302000Z - 311200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THERE IS A
MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
NORTHEAST...THE NORTHERN TO CENTRAL HIGH PLAINS...AND KANSAS INTO
THE SOUTHERN GREAT LAKES...

...SUMMARY...
Widely scattered strong to severe thunderstorms are possible from
Kansas into the Mid Mississippi Valley and southern Great Lakes, and
over parts of the Mid-Atlantic/Northeast region, and from southern
Montana across Wyoming and Colorado.

...20z Update...
The previous forecast largely remains on track with only minor
adjustments needed. Hail/wind risk probabilities were adjusted
across portions of KS into MO and IL to better align with ongoing
convection and the progression of a residual outflow boundary in
IL/MO and a southward moving cold front in KS. See the previous
discussion below and MCDs #1847 and 1848 for additional details.

..Moore.. 07/30/2025

.PREV DISCUSSION... /ISSUED 1130 AM CDT Wed Jul 30 2025/

...Mid MS Valley...
Radar/visible-satellite mosaic shows a sub-severe squall line from
near Saint Louis into northern IL moving slowly east-southeastward
across the Corn Belt. Some rejuvenation of storm intensity may
occur with storms along the leading edge of the cold pool as it
moves into eastern IL/IN/OH/Lower MI. Isolated 50-65 mph gusts
capable of wind damage may occur with this activity. Farther west,
a weak mid-level shortwave disturbance is implied in satellite
imagery near the KS/NE border, and a surface low was analyzed over south-central KS along the trailing frontal zone. These features
may aid in focusing scattered storms this afternoon over parts of
central and eastern KS. The boundary layer continues to
heat/destabilize with surface dewpoints ranging from the upper 60s
to mid 70s across central and eastern KS. Isolated severe gusts and
possibly large hail may accompany the stronger storms late this
afternoon into the evening.

...High Plains...
A seasonably moist airmass resides across the central and northern
Rockies and adjacent plains late this morning. Water-vapor imagery
and earlier radar mosaic data implied a weak disturbance cresting a
ridge over the northern WY/southern MT border. Influence from this
disturbance and westerly 40-50 kt high-level flow will support some
storm organization potential. Forecast soundings across central WY
show 1000-1500 J/kg MLCAPE and effective shear 30-40 kt. This may
support a couple of supercells capable of threat for large hail.
Upscale growth into a linear cluster may evolve in central WY late
this afternoon into the early evening, coincident with a risk for
severe gusts. Farther south, storm coverage may be locally greater
across the Front Range and I-25 corridor from Denver to Pueblo.
Isolated to widely scattered wind/hail seem likely with the stronger cores/outflow. Elsewhere, it appears an isolated risk for severe
will encompass the larger general area from southern MT into eastern
CO.

...Northeast...
A weak surface cold front will sag southward into a moist/adequately
unstable airmass across New England and parts of NY/PA this
afternoon into the evening. Low-level convergence along the front
will be weak and will limit overall storm coverage. However, cool
temperatures aloft and steep low-level lapse rates will promote a
risk of gusty/damaging winds and at least small hail in the storms
that form this afternoon. For short-term details regarding the
severe risk in portions of northern New England, refer to MCD #1846.

$$

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ACUS01 KWNS 310102
SWODY1
SPC AC 310100

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0800 PM CDT Wed Jul 30 2025

Valid 310100Z - 311200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
KANSAS AND THE CENTRAL TO NORTHERN HIGH PLAINS...

...SUMMARY...
A few instances of severe wind/hail remain possible across parts of
Kansas and the central/northern High Plains this evening.

...Synopsis...
Mid-level troughing persists across the western U.S. as an upper
ridge remains in place over the central CONUS. A mid-level trough
continues to progress across the Northeast, albeit with diminishing
buoyancy. Thunderstorm clusters will persist for many areas west of
the Rockies given large-scale lift and adequate buoyancy. Storms
east of the Rockies are thriving primarily on rich low-level
moisture and residual buoyancy from strong diurnal heating. A chance
for an additional instance of severe wind or hail remain with storms
across Kansas, where buoyancy is strongest in the central/southern
Plains. Storms are strengthening along and to the east of the
central/northern Rockies where both buoyancy and deep-layer are
maximized (i.e. 1000-2000 J/kg MLCAPE and 30-50 kts in place), and
it is here where isolated severe wind and hail may still be
observed.

..Squitieri.. 07/31/2025

$$

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ACUS01 KWNS 310601
SWODY1
SPC AC 310600

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Thu Jul 31 2025

Valid 311200Z - 011200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
THE MID ATLANTIC AND THE CENTRAL HIGH PLAINS...

...SUMMARY...
A few strong storms, capable of mainly damaging winds, are possible
across the Mid-Atlantic and Arkansas during the afternoon. Severe
wind and hail producing storms are also expected across the northern
Rockies into the central High Plains.

...Synopsis...
An upper trough will traverse the Northeast while an upper ridge
persists over the Central U.S. and broad upper troughing becomes
established over the Interior West today. A surface low will develop
across the Mid-Atlantic this afternoon with the passage of an
embedded mid-level impulse within the broader trough, which will
encourage widespread strong thunderstorm development. Across
portions of Arkansas and immediate adjacent areas, a weak impulse
will support the development of at least scattered strong
thunderstorms amid ample buoyancy. Across the northern Rockies into
the northern and central High Plains, an embedded mid-level impulse
will result in the initiation of several thunderstorm clusters,
which will move over the higher terrain during the afternoon. Given
adequate buoyancy and shear in these regions, strong to severe
storms are possible.

...Mid Atlantic...
Thunderstorms should develop during the afternoon, as surface
temperatures warm well into the 80s F, and quickly translate
eastward given 40+ kts of 500 mb westerly flow. Surface dewpoints
will reach well into the 70s F, supporting 2000-3000 J/kg MLCAPE
despite mediocre mid-level lapse rates. The strong instability and
30-40 kts of effective bulk shear will encourage the development of
strong multicells and perhaps a transient supercell. Damaging gusts
are the main threat, though an instance or two of hail are possible,
mainly during the afternoon and early evening hours.

...Arkansas...
By early afternoon, clusters of thunderstorms will develop amid
strong heating and minimal MLCINH. While lapse rates will be modest,
surface dewpoints in the mid 70s F will boost MLCAPE to around 4000
J/kg. Despite weak shear, strong pulse-cellular and multicellular
clusters will develop with wet downburst potential, the strongest of
which may produce a couple of damaging gusts.

...Parts of the Northern Rockies into the Central High Plains...
By mid-afternoon, at least scattered thunderstorms will develop atop
the higher terrain of the Rockies, driven by a glancing mid-level
impulse and orographic lift. These storms will progress eastward
toward the northern/central High Plains amid 8+ C/km mid-level lapse
rates (contributing to 2000 J/kg MLCAPE) and 20-40 kts of effective
bulk shear. Forecast soundings show hodographs with modest
elongation and some curvature, suggesting that both multicellular
complexes and supercells are possible. The stronger storms will
support a severe hail/wind threat, with the best chance of hail
being with supercells.

..Squitieri.. 07/31/2025

$$

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