ACUS48 KWNS 151002
SWOD48
SPC AC 151000

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CST Sun Feb 15 2026

Valid 181200Z - 231200Z

...DISCUSSION...
Medium-range model output suggests that amplified large-scale
troughing, initially centered near the Pacific coast at the outset
of the period, will gradually develop eastward, across and east of
the Rockies during the latter half of the week into next weekend.
It appears that this will occur in generally piecemeal fashion, as a
series of smaller-scale/lower amplitude perturbations. However,
given the presence of an initially seasonably warm environment to
the lee of the Rockies, potential exists for periodic lee surface
cyclogenesis, possible strong.

To this point, guidance has exhibited rather poor predictability
with these features, but there does appear at least somewhat greater
certainty in potential for substantive surface cyclogenesis by
Thursday, across the central Great Plains toward the Great Lakes
region. Even so, it still appears that preceding Gulf
boundary-layer moistening and inland return flow will only support
limited moistening within the developing warm sector across the
middle Mississippi Valley through much of the day Thursday. By
Thursday night, there are indications that a modest late moisture
surge into the lower Ohio Valley could contribute to increasing
convective potential, but the extent of the severe threat remains
unclear at this time.

Guidance still indicates that better low-level moisture return may
commence ahead of the cold front trailing the cyclone, across parts
of the Ohio/Tennessee Valleys through Ark-La-Tex and southern Great
Plains Friday into Saturday, as upstream perturbations begin to
emerge from the West. However, current model output suggests that
renewed cyclogenesis may be more subdued, and it is possible that
convection may tend to develop and train along and to the cool side
of the front and/or outflow, with uncertain severe weather
potential.

..Kerr.. 02/15/2026

= = =
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (1:2320/105)

ACUS48 KWNS 161002
SWOD48
SPC AC 161000

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CST Mon Feb 16 2026

Valid 191200Z - 241200Z

...DISCUSSION...
Medium-range guidance indicates that a sub-1000 mb surface cyclone,
centered across the central Great Plains at the outset of the
period, may undergo a period of further deepening as it migrates
across and northeast of the lower Missouri Valley, toward the Great
Lakes, late Thursday afternoon or evening. Perhaps most notable,
latest model output appears a bit more aggressive than last night
concerning a corridor of warm sector moisture return into the
vicinity of the confluence of the Mississippi and Ohio Rivers. It
now appears that this may include surface dew points increasing as
high as the upper 50s to lower 60s F by around 20/00Z, which may
advect at least a bit further east-northeastward through the lower
Ohio Valley, before being cut off later Thursday evening. Though
still somewhat modest, and perhaps only supportive of CAPE on the
order of 500 J/kg, this probably will be conducive to severe
thunderstorm development, in the presence of more than sufficient
deep-layer shear and large-scale ascent to support organized
convection. This may include supercells with potential to produce
tornadoes, and perhaps an upscale growing cluster with strong to
severe gusts for a period Thursday evening.

It appears that this cyclone will weaken substantively across the
Great Lakes region on Friday, with renewed cyclogenesis possible to
the east of the Blue Ridge, or perhaps primarily offshore of the Mid
Atlantic coast. So, while increasing low-level moisture return may
continue into the warm sector across parts of the Southeast and Mid
Atlantic, the extent to which mid/upper support remains conducive to
severe weather potential remains unclear.

By late this coming weekend into at least next Monday, convective
potential appears likely to diminish as large-scale mid/upper
ridging expands across and east of the Rockies toward the Atlantic
Seaboard.

..Kerr.. 02/16/2026

= = =
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (1:2320/105)

ACUS48 KWNS 170952
SWOD48
SPC AC 170950

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0350 AM CST Tue Feb 17 2026

Valid 201200Z - 251200Z

...DISCUSSION...
In general, the latest medium-range guidance indicates that an
initially notable surface cyclone over the upper Great Lakes region
at the outset of the period will undergo substantive weakening, as a
supporting short wave impulse becomes sheared and weakens to the
south of a blocking mid-level ridge centered over southern Hudson
Bay. It appears that secondary cyclogenesis across and offshore of
the Mid Atlantic coast Friday through Friday night will be subdued,
with a trailing cold front stalling across the southern Atlantic
through Gulf coast vicinity into Saturday, near the southern
periphery of the seasonably strong westerlies.

Forcing for ascent associated with trailing short wave
perturbations, emerging from larger-scale mid-level troughing
progressing out of the West, may remain largely to the cool side of
the surface frontal zone. However, further moistening along it
could support sufficient destabilization for vigorous, perhaps
upscale growing and training, thunderstorm development, which could
pose at least some risk for producing severe hail and wind. While
severe thunderstorm probabilities are being maintained at less than
15 percent in this outlook, it is still possible that this could
change in later outlook updates for the Friday/Saturday time period.

Thereafter, amplifying mid/upper flow across the eastern
mid-latitude Pacific into North America through early next week
appears likely to include building large-scale ridging inland of the
Pacific coast through the Mississippi Valley. Beneath the confluent
regime in the wake of digging downstream troughing, cold surface
ridging is forecast to build southward to the lee of the Rockies,
through much of the Gulf Basin. Associated low-level drying and
stabilization probably will tend to limit convective potential
through the remainder of the period.

..Kerr.. 02/17/2026

= = =
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (1:2320/105)

ACUS48 KWNS 180957
SWOD48
SPC AC 180956

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0356 AM CST Wed Feb 18 2026

Valid 211200Z - 261200Z

...DISCUSSION...
Latest medium-range guidance indicates little further amplification
of large-scale mid-level troughing across the eastern mid-latitude
Pacific, but a broad embedded cyclonic circulation, with a number of
shorter wavelength perturbations pivoting around its periphery, may
continue to evolve through this coming weekend. These may be
accompanied by multiple areas of surface cyclogenesis, including one
cyclone with an occluding front which may advance into northern
Pacific coastal areas late Saturday night into early Sunday.
However, it appears that the coldest mid-level air, supportive of boundary-layer based destabilization conducive to thunderstorms,
might remain offshore.

At the same time, downstream amplification of mid-level ridging may
continue across the Rockies and Great Plains Saturday into Sunday,
with subsequent amplification of troughing east of the Mississippi
Valley through areas offshore of the southern Atlantic Seaboard
Sunday through Monday. This is likely to be accompanied by cold
surface ridging building south-southeastward to the lee of the
Rockies, through much of the Gulf Basin, which probably will
suppress convective potential through the remainder of the period.

While the environment may be at least conditionally supportive of
strong to severe thunderstorm development along a frontal zone
across parts of the eastern Gulf Coast into southern Atlantic Coast
early this coming weekend, surface frontal wave development across
inland areas on Saturday is forecast to remain weak, tending to
minimize this potential.

..Kerr.. 02/18/2026

= = =
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (1:2320/105)

ACUS48 KWNS 190950
SWOD48
SPC AC 190948

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0348 AM CST Thu Feb 19 2026

Valid 221200Z - 271200Z

...DISCUSSION...
Downstream of initially amplified mid/upper ridging forecast to
expand east of the Rockies through the Mississippi Valley, models
indicate that troughing will amplify further, into and across the
southern Atlantic Seaboard late this coming weekend into early next
week. As it does, much more substantive cyclogenesis appears likely
to ensue offshore of the southern Mid Atlantic coast, toward the
western north Atlantic, while cold surface ridging builds southward
through much of the Gulf Basin before gradually weakening.

Around the same time, and thereafter, guidance indicates that the
blocked regime across the central into eastern mid-latitude Pacific
will become suppressed. It appears that the initially broad
offshore cyclonic mid-level circulation will become more compact,
and remain offshore, while flow inland of the Pacific coast through
the Atlantic Seaboard trends less amplified and generally
west-northwesterly through the middle to latter portion of next
week.

Beneath this regime, surface troughing may initially deepen across
the Great Plains, before a cold front, associated with a short wave perturbation digging from the higher latitudes, advances south of
the Canadian/U.S. border through much of the central and eastern
U.S. by the end of the period. However, even by that time, it
appears that Gulf boundary-layer moistening and inland return flow
will be too limited to support an appreciable risk for severe
storms.

..Kerr.. 02/19/2026

= = =
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (1:2320/105)

ACUS48 KWNS 190956
SWOD48
SPC AC 190954

Day 4-8 Convective Outlook RESENT 1
NWS Storm Prediction Center Norman OK
0354 AM CST Thu Feb 19 2026

Valid 221200Z - 271200Z

...DISCUSSION...
Downstream of initially amplified mid/upper ridging forecast to
expand east of the Rockies through the Mississippi Valley, models
indicate that troughing will amplify further, into and across the
southern Atlantic Seaboard late this coming weekend into early next
week. As it does, much more substantive cyclogenesis appears likely
to ensue offshore of the southern Mid Atlantic coast, toward the
western north Atlantic, while cold surface ridging builds southward
through much of the Gulf Basin before gradually weakening.

Around the same time, and thereafter, guidance indicates that the
blocked regime across the central into eastern mid-latitude Pacific
will become suppressed. It appears that the initially broad
offshore cyclonic mid-level circulation will become more compact,
and remain offshore, while flow inland of the Pacific coast through
the Atlantic Seaboard trends less amplified and generally
west-northwesterly through the middle to latter portion of next
week.

Beneath this regime, surface troughing may initially deepen across
the Great Plains, before a cold front, associated with a short wave perturbation digging from the higher latitudes, advances south of
the Canadian/U.S. border through much of the central and eastern
U.S. by the end of the period. However, even by that time, it
appears that Gulf boundary-layer moistening and inland return flow
will be too limited to support an appreciable risk for severe
storms.

..Kerr.. 02/19/2026

= = =
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (1:2320/105)

ACUS48 KWNS 200914
SWOD48
SPC AC 200913

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0313 AM CST Fri Feb 20 2026

Valid 231200Z - 281200Z

...DISCUSSION...
The forecast period will begin with a highly amplified upper-air
pattern with a ridge over the Rockies and a deep trough over the
eastern US. By the middle of the next week, this mid-level flow
regime will transition to one characterized as broadly northwest
flow from the Pacific Northwest toward the Southeast United States.
This flow regime will help drive a mid-level trough/surface cold
front southeast through the Plains toward the end of next week.
However, limited moisture return ahead of this trough/cold front
should temper any severe potential.

The front is expected to push south into at least the northern Gulf.
This resulting cold/dry air intrusion into the northern Gulf will
limit the potential for appreciable moisture return and subsequent thunderstorm/severe thunderstorm potential through the rest of the
forecast period.

..Marsh.. 02/20/2026

= = =
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (1:2320/105)

ACUS48 KWNS 210932
SWOD48
SPC AC 210931

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0331 AM CST Sat Feb 21 2026

Valid 241200Z - 011200Z

...DISCUSSION...
At the start of the forecast period, a dry airmass will remain
across much of the United States. The culprit being a large surface
anticyclone located across the northern Gulf Coast states
suppressing moisture return. By late Tuesday (Day 4), the
anticyclone will have moved into the eastern Gulf, with southerly
winds advecting moisture northward into the Southern Plains.

Thunderstorm chances may return to portions of the Southern Plains
into the Southeast overnight Wednesday into Thursday as a surface
cold front pushes south into the area. At this time, the quality of
the moisture return and poor lapse rates suggests limited, if any,
severe potential as the front moves through.

The aforementioned front will stall/wash out across the northern
Gulf states late on Thursday into Friday (Days 6 and 7) with modest
moisture return developing across the Southern Plains Friday into
Saturday (Days 7 and 8). This will be short lived as ensemble
guidance suggests a seasonably strong cold front moving into/through
the Southern Plains next weekend or early the following week. Once
again, current guidance indicates the quality of moisture return and
poor lapse rates should limit any severe potential.

..Marsh.. 02/21/2026

= = =
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (1:2320/105)

ACUS48 KWNS 221000
SWOD48
SPC AC 220958

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0358 AM CST Sun Feb 22 2026

Valid 251200Z - 021200Z

...DISCUSSION...
A sharp mid-level trough will move across the US early in the
forecast period (Wednesday and Thursday -- Days 4 and 5). This wave
will induce surface cyclogenesis across the Central Plains on
Wednesday, and this low will quickly move east across the Ohio
Valley on Thursday. Southerly winds ahead of the low will draw Gulf
moisture northward across much of the Southeast.

Showers and perhaps a few thunderstorms will develop on Thursday
along and head of an eastward advancing cold front to the south of
the aforementioned surface low. Forecast soundings and low-level
wind fields show strong low-level wind fields atop a cool, moist
boundary layer. Despite little to any instability, strong
convergence along the cold front may support a narrow band of forced
ascent. Given the strength of the low-level wind fields, a few
strong wind gusts may reach the surface across portions of the
Tennessee Valley on Thursday afternoon/evening, even absent
lightning. Confidence in the specifics of this evolution are too low
to warrant severe probabilities, but will be monitored in subsequent
forecasts.

This cyclone will push a front south toward the northern Gulf coast
by Friday, where southward advancement will stall. This front should
wash out/redevelop northward next weekend as southerly flow takes
hold and begins to advect moisture northward.

..Marsh.. 02/22/2026

= = =
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (1:2320/105)

ACUS48 KWNS 230838
SWOD48
SPC AC 230837

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0237 AM CST Mon Feb 23 2026

Valid 261200Z - 031200Z

...DISCUSSION...
The upper-air pattern across the US will remain characterized as
broad, fast, northwest flow for most of the forecast period.
Embedded within this flow, a series of shortwave troughs will move
across the US. The first, and potentially most impactful of these
troughs will move across the eastern US on Thursday and Friday (Days
4 and 5).

A surface low will develop across portions of the Tennessee Valley
early in the day Thursday in response to increasing large-scale
ascent associated with the aforementioned shortwave trough. This low
will quickly move east then northeast, pushing a cold front through
much of the Southeast US. A couple days of moisture return will
result in surface dewpoints in the 50Fs to perhaps low 60Fs ahead of
this cold front. Despite poor lapse rates and meager buoyancy
profiles, strong convergence along the front should yield a narrow
band of forced ascent/convection. A strong low-level jet and curved
low-level hodographs indicated in forecast soundings may support a
few isolated damaging wind gusts or perhaps a brief tornado or two
with this convection, even absent widespread lightning. Although
confidence is increasing that a band of strongly forced convection
will occur along the cold front, confidence remains too low in where
damaging wind gusts/brief tornado may occur to introduce
unconditional 15% severe probabilities.

In the wake of this cold front, the severe potential looks to be
rather limited as surface moisture is suppressed south into the
northern Gulf until next weekend at the earliest, when southerly
return flow should develop across Texas and Oklahoma.

..Marsh.. 02/23/2026

= = =
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (1:2320/105)

ACUS48 KWNS 240947
SWOD48
SPC AC 240946

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0346 AM CST Tue Feb 24 2026

Valid 271200Z - 041200Z

...DISCUSSION...
The severe potential will remain low through this forecast period as
the atmosphere undergoes a pattern change.

Ensemble guidance is in good agreement that in the wake of a
departing trough, a frontal boundary will stall across the northern
Gulf Coast on Friday (Day 4), largely confining appreciable
low-level moisture to the Gulf. The front remains loosely in place
until late this weekend (Sunday -- Day 6) when it washes out and
redevelops farther north. This occurs coincident with a transition
of the upper-air pattern from a single belt of broadly northwest
flow to a split flow regime (ridge over trough).

By early next week (Days 7 and 8) an expansive upper-level ridge
will take shape across much of the US while a closed low develops
and then opens up beneath this ridge across the Southwest. The
position and evolution of the closed low should place modest
southwest flow across much of the Plains by the end of the forecast
period. Southerly winds to the east of the resulting High Plains lee
trough should support a gradual moistening of the Plains' low-level environment.

Although ensemble guidance is in relatively good agreement about the large-scale pattern evolution, considerable differences exist with
the finer details, such as quality and northward extent of the
moisture return, timing of specific feature evolution, and resulting
placement of any precipitation potential -- including thunderstorms.
In any event, the overall resulting pattern and pattern recognition
favors an increase in thunderstorm and perhaps severe potential
across the central US just beyond this forecast period.

..Marsh.. 02/24/2026

= = =
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (1:2320/105)

ACUS48 KWNS 250954
SWOD48
SPC AC 250953

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0353 AM CST Wed Feb 25 2026

Valid 281200Z - 051200Z

...DISCUSSION...
Ensemble guidance continues to support a large-scale change to the
overall upper-air pattern during this forecast period. The western ridge/eastern trough should flip, evolving toward a western trough
and eastern ridge. As this happens, southwest mid-level flow into
the central US will support a gradual warming/moistening of the
Plains' low-level environment. Details of how far north and the
overall quality of the moisture return remain to be seen.

This moisture return will begin in earnest on Saturday (Day 4) as
southerly winds take hold across the central US. However, a cold
front will suppress this low-level moisture south into central Texas
on Sunday and Monday (Days 5 and 6), with some guidance members
suggesting a reinforcing frontal push on Tuesday.

By the middle of next week (Days 7 and 8), the frontal boundary
should weaken across Texas and redevelop northward. This will allow
low-level moisture to begin advancing northward into the Central
Plains. However the speed and strength of this low-level moisture
advection varies greatly between different ensembles and even within
the membership of specific ensembles. As such, the overall potential
for organized severe weather on any day looks to be too low for
unconditional probabilities. However, pattern recognition suggests
thunderstorm (and severe) potential should increase across portions
of the central US just beyond this forecast period.

..Marsh.. 02/25/2026

= = =
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (1:2320/105)

ACUS48 KWNS 251040
SWOD48
SPC AC 251039

Day 4-8 Convective Outlook RESENT 1
NWS Storm Prediction Center Norman OK
0439 AM CST Wed Feb 25 2026

Valid 281200Z - 051200Z

...DISCUSSION...
Ensemble guidance continues to support a large-scale change to the
overall upper-air pattern during this forecast period. The western ridge/eastern trough should flip, evolving toward a western trough
and eastern ridge. As this happens, southwest mid-level flow into
the central US will support a gradual warming/moistening of the
Plains' low-level environment. Details of how far north and the
overall quality of the moisture return remain to be seen.

This moisture return will begin in earnest on Saturday (Day 4) as
southerly winds take hold across the central US. However, a cold
front will suppress this low-level moisture south into central Texas
on Sunday and Monday (Days 5 and 6), with some guidance members
suggesting a reinforcing frontal push on Tuesday.

By the middle of next week (Days 7 and 8), the frontal boundary
should weaken across Texas and redevelop northward. This will allow
low-level moisture to begin advancing northward into the Central
Plains. However the speed and strength of this low-level moisture
advection varies greatly between different ensembles and even within
the membership of specific ensembles. As such, the overall potential
for organized severe weather on any day looks to be too low for
unconditional probabilities. However, pattern recognition suggests
thunderstorm (and severe) potential should increase across portions
of the central US just beyond this forecast period.

..Marsh.. 02/25/2026

= = =
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (1:2320/105)

ACUS48 KWNS 260958
SWOD48
SPC AC 260956

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0356 AM CST Thu Feb 26 2026

Valid 011200Z - 061200Z

...DISCUSSION...
Early in the forecast period a transition across the western US will
take place as the low-amplitude ridge over the Great Basin/Southwest
shifts eastward, giving way to an amplifying trough over the West.
Several speed maxima are forecast to traverse the flow while it
remains primarily northwesterly over the central US early in the
period. At the surface, uncertainty remains regarding the southern
extent of the arctic front pushing into the Plains on Day 3.
Uncertainties in the position of this front will cause low
confidence in the projected quality of the low-level moisture
recovery across the southern Plains through Tuesday. As the
upper-air pattern across the central US transitions from
northwesterly to southwesterly, and return flow commenses, the
shallow nature of the modified arctic airmass may initially limit
the northward penetration of the richest theta-e air.

As the period progresses into Wednesday and Thursday, ensemble
guidance remains in general agreement regarding the transition to an
amplified western trough and central-to-eastern ridge. However, the
timing and phasing of individual shortwaves moving into the Plains
remains a source of forecast uncertainty.

The first meaningful shortwave is forecast to eject into the Plains
early Wednesday, inducing surface cyclogenesis that should support a
northward advancement of the warm sector. Any severe risk with this
trough on Wednesday (Day 7) will be predicated on the evolution of
the moisture return on prior days.

On Thursday, a second, more potent trough is forecast to approach
the Plains. Current ensemble guidance shows quite a bit more
variance with the timing, amplitude, and evolution of this second
trough. Some guidance brings this wave out as single, potent trough,
with other guidance suggesting a series of more subtle shortwave
troughs ejecting into the Plains from Thursday into Saturday. These discrepancies will have an impact on the location, timing, and
magnitude of any potential severe weather threat.

Despite these timing differences, the synoptic setup (increasing
low-level moisture, strengthening southwest flow aloft, repeated
cyclogenesis) is favorable for organized severe weather over the
Plains and lower Mississippi Valley. While the severe weather threat
should increase by Wednesday and Thursday (Days 7 and 8), the
specific orientation of frontal boundaries and the northward extent
of the moisture return will be highly dependent on the evolution of
the upper-lows. Given that models tend to struggle with handling the
details of pattern changes, will hold off on trying to highlight any
specific corridor for severe probabilities for Wednesday and
Thursday at this time.

..Marsh.. 02/26/2026

= = =
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (1:2320/105)

ACUS48 KWNS 271001
SWOD48
SPC AC 270959

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CST Fri Feb 27 2026

Valid 021200Z - 071200Z

...DISCUSSION...
...Monday/Day 4 to Tuesday/Day 5...
At mid-levels, a trough is forecast to move across California on
Monday as zonal flow remains in place over the central and eastern
U.S. On Tuesday, the trough is forecast to move eastward across the
Desert Southwest, as flow becomes southwesterly in the south-central
states. A moist airmass will likely be in place on Monday and
Tuesday from eastern parts of the southern Plains into the lower to
mid Mississippi Valley. Thunderstorm development will be possible
each afternoon and evening across parts of the moist airmass. In
areas that destabilize the most, a marginal severe threat may
develop.

...Wednesday/Day 6 to Friday/Day 8...
On Wednesday, the trough is forecast to move into the southern and
central High Plains, as an associated mid-level jet ejects
northeastward across the southern High Plains. At the surface, a
cold front is forecast to move into the southern Plains, as a moist
airmass spreads northward from north Texas into southern and eastern
Oklahoma. As surface temperatures warm during the day, thunderstorms
appear most likely to form along the cold front, and further south
across parts of the warm sector. Moderate deep-layer shear is
evident on model forecasts which should support a severe threat
during the afternoon and evening, with a potential for large hail
and severe wind gusts. While confidence is high enough to add a
severe threat area across the southern Plains, variance does exist
concerning the timing of the shortwave trough. If the trough moves
across the southern Plains faster, then the area could need to be
adjusted.

On Thursday, the mid-level trough is forecast to eject northeastward
into the Great Lakes region, as a large upper-level trough digs into
the Desert Southwest. Southwesterly mid-level flow will likely be in
place over parts of the Great Plains, with a moist and unstable
airmass remaining over much of Texas and Oklahoma. As surface
temperatures warm, isolated strong to severe storms will be possible
in areas that destabilize the most. At this time, there is
uncertainty regarding the magnitude of the threat because some
solutions move a shortwave ridge northeastward across the
south-central U.S.

On Friday, model forecasts suggest that a large-scale upper-level
trough will move through the western U.S. Ahead of this feature,
thunderstorms will continue to be possible over parts of the
southern and central Plains, where a moist and unstable airmass is
forecast to be in place. However, a significant amount of variance
exists among the model solutions, suggesting that uncertainty is
substantial concerning the magnitude and spacing of any severe
threat.

..Broyles.. 02/27/2026

= = =
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (1:2320/105)

ACUS48 KWNS 280954
SWOD48
SPC AC 280952

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0352 AM CST Sat Feb 28 2026

Valid 031200Z - 081200Z

...DISCUSSION...
...Tuesday/Day 4 and Wednesday/Day 5...
On Tuesday, a mid-level trough will move eastward across the Desert
Southwest, as southwesterly flow remains in place over the southern
Plains. As the trough approaches Tuesday night, scattered elevated thunderstorms will be possible from the Red River northeastward into
the mid Mississippi Valley. From Tuesday night into Wednesday, a
moist airmass will spread northward from east-central Texas into the
Arklatex and Ozarks. Thunderstorm development will be possible near
the boundary from central Oklahoma into southern Missouri during the
day on Wednesday, and further southeast across the warm sector in
the afternoon and evening. Model forecasts continue to show moderate instability ahead of the front. In addition, a mid-level jet streak
is forecast to pass through the southern Plains during the
afternoon, creating deep-layer shear sufficient for severe storms.
Supercells with wind damage and isolated large hail will be
possible. Model solutions are in better agreement this run,
suggesting the severe threat will be a bit further east than was
previously forecast. For this reason, the severe threat area has
been adjusted eastward towards the Ark-La-Tex.

...Thursday/Day 6 to Saturday/Day 8...
On Thursday, the shortwave trough is forecast to move through the
mid Mississippi Valley, as the cold front advances southeastward
into the Ark-La-Tex and mid Mississippi Valley. Thunderstorms will
be possible near the front during the day into the evening.
Deep-layer shear and instability are forecast to be somewhat
limited, which should keep any severe threat marginal.

From Thursday night into Friday, southwesterly mid-level flow is
forecast to strengthen over the south-central states. In response,
moisture advection will likely continue over the southern Plains as
moderate instability re-develops across much of the southern Plains.
Scattered thunderstorms should form over parts of this airmass
Thursday night from west-central Texas north-northeastward into
parts of the central Plains. The potential for storm development
should continue into Friday along the northern edge of the moist
airmass from north-central Texas northeastward into the Ozarks.
Although a severe threat could develop over parts of the southern
Plains and Ozarks Friday afternoon and evening, there is
considerable uncertainty, mainly due to variance among model
solutions.

On Saturday, am amplified upper-level trough is forecast to develop
over the western U.S., as mid-level flow becomes south-southwesterly
from the Gulf Coast States into the mid Mississippi Valley. A moist
airmass is forecast over much of the Gulf Coast states, where
scattered thunderstorms will be possible during the day. Although a
severe threat could develop during the day, uncertainty is high
concerning the placement of a more concentrated severe threat area.

..Broyles.. 02/28/2026

= = =
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (1:2320/105)

ACUS48 KWNS 011001
SWOD48
SPC AC 010959

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CST Sun Mar 01 2026

Valid 041200Z - 091200Z

...DISCUSSION...
...Wednesday/Day 4 to Thursday/Day 5...
On Wednesday, model forecasts continue to move a mid-level shortwave
trough across the southern Plains. A cold front is forecast to
advance southeastward into Oklahoma as a moist and unstable airmass
resides southward from the front over much of the southern Plains.
Surface dewpoints across southeast Oklahoma and north-central to
northeast Texas should be in the lower to mid 60s F, and moderate
instability will be possible by afternoon. Thunderstorm development
appears likely across parts of this unstable airmass from the mid
afternoon into the evening. Moderate deep-layer shear should support
a severe threat, with a potential for large hail and damaging wind
gusts associated with supercells.

On Thursday, the shortwave trough is forecast to move into the mid
Mississippi Valley, as a much larger upper-level trough moves
through the Desert Southwest. A moist and unstable airmass should
remain in place over the southern Plains. However, large-scale
ascent should be weak between these two systems, which should dampen
the severe potential across most of the south-central U.S. The most
likely location for an isolated to marginal severe threat would be
in the Ark-La-Tex Thursday afternoon.

...Friday/Day 6 to Sunday/Day 8...
At mid-levels, southwest flow is forecast across much of the central
U.S. on Friday, as a large trough remains over the southwestern
states. Moisture advection is expected to continue over the Great
Plains and Upper Midwest along a corridor of strong low-level flow.
Model forecasts are in general agreement that moderate instability
will develop over much of this airmass by Friday afternoon, and that
scattered thunderstorms will form. Convective development will be
supported by the right entrance region of a mid-level jet ejecting northeastward through the central Plains. This mid-level jet will be
associated with moderate to strong deep-layer shear, supporting
scattered severe storms potentially across a large part of the moist
sector. The current thinking is that the severe threat will be
maximized during the late afternoon and evening from central Texas northeastward into the lower Missouri Valley. Large hail and
damaging wind gusts are expected to the primary threats, but a few
tornadoes remain possible.

On Saturday, the upper-level system in the central U.S. is forecast
to move into the Great Lakes region, as a cold front advances
quickly southeastward into the western Gulf Coast states, and lower
Mississippi Valley. An isolated severe threat could develop ahead of
the front Saturday afternoon, but confidence is low concerning the
spatial distribution of any threat. On Sunday, isolated to scattered thunderstorms will again be possible in the Gulf Coast region.
However, deep-layer shear is forecast to be weak over much of this
area, suggesting any severe potential should remain marginal.

..Broyles.. 03/01/2026

= = =
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (1:2320/105)

ACUS48 KWNS 020959
SWOD48
SPC AC 020958

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0358 AM CST Mon Mar 02 2026

Valid 051200Z - 101200Z

...DISCUSSION...
...Thursday/Day 4 and Friday/Day 5...
At mid-levels, a shortwave trough is forecast to move through the
mid Mississippi Valley on Thursday as flow remains southwesterly
across the south-central U.S. An upper-level system will be located
in the Desert Southwest. At the surface, moisture advection is
forecast across the southern Plains, where surface dewpoints will be
mostly in the 50s and 60s F by afternoon. As surface temperatures
warm during the day, an axis of moderate instability is forecast to
develop to the east of a dryline from west-central Texas
north-northeastward into the eastern Texas Panhandle and western
Oklahoma. Along this axis of instability, moderate deep-layer is
forecast, along with steep mid-level lapse rates. This will likely
support a severe threat during the afternoon and evening. Supercells
with large hail, damaging wind gusts and a tornado threat will be
possible.

On Friday, mid-level southwesterly flow will strengthen across parts
of the southern and central Plains, as a mid-level jet ejects
northeastward into the central U.S. At the surface, a moist airmass
with moderate instability is forecast to be in place by afternoon
from north-central Texas north-northeastward into the lower Missouri
Valley. Model forecasts are in agreement that scattered
thunderstorms will develop across this unstable airmass during the
afternoon and evening. Moderate deep-layer shear and steep mid-level
lapse rates should be favorable for supercells with large hail. Wind
damage and tornadoes will also be possible with supercells and
bowing line segments. Some solutions suggest that the threat will
persist into the overnight period as a low-level jet ramps up across
the region.

...Saturday/Day 6 to Monday/Day 8...
Mid-level southwesterly flow is expected to continue over the
south-central U.S. on Saturday, as a cold front moves southward
across the southern Plains and Ozarks. To the south of the front,
the models forecast pockets of moderate instability, and suggest
that scattered to numerous thunderstorms will develop. In addition,
moderate to strong deep-layer shear is forecast across the northern
edge of the moist sector. Model consensus suggests that a severe
threat will develop Saturday afternoon and evening, mainly from
west-central Texas northeastward into the western Ozarks.

The cold front is forecast to continue moving southward into the
western Gulf Coast states on Sunday. Scattered thunderstorms are
forecast to develop near and to the south of the front Sunday
afternoon, where an isolated severe threat will be possible.
Confidence is low concerning the spatial distribution of any
potential threat. On Monday, a shortwave ridge is forecast to move
over the top of a moist airmass in the southern Plains. This
scenario could support an isolated severe threat in the afternoon.
However, uncertainty is high at this range in the forecast period.

..Broyles.. 03/02/2026

= = =
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (1:2320/105)

ACUS48 KWNS 030954
SWOD48
SPC AC 030952

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0352 AM CST Tue Mar 03 2026

Valid 061200Z - 111200Z

...DISCUSSION...
...Friday/Day 4 and Saturday/Day 5...
A strong upper-level system is forecast to eject northeastward into
the central High Plains on Friday, as an associated 60 to 80 knot
mid-level jet translates northeastward ahead of the trough. At the
surface, a moist and unstable airmass will likely be in place from
central and east Texas northward into the lower Missouri Valley.
Warming surface temperatures and increasing low-level convergence
will support scattered convective initiation to the west of the
moist axis. Storms are expected to grow upscale in the mid to late
afternoon, moving eastward toward an axis of strong low-level flow.
Moderate instability, strong deep-layer shear and steep lapse rates
will be favorable for supercells. Supercells should be capable of
producing tornadoes, large hail and severe wind gusts. The greatest
potential is forecast from near the Red River in north Texas north-northeastward across eastern Oklahoma into eastern Kansas and northwestern Missouri, where a 30 percent contour has been added. A
severe threat is also forecast northeastward into parts of the mid
to upper Mississippi Valley, where strong deep-layer shear and
sufficient low-level moisture will be in place for a severe threat.

On Saturday, the upper-level system is forecast to move through the north-central U.S., as a cold front advances southeastward into the
Ark-La-Tex, mid Mississippi Valley, and lower Great Lakes. Scattered
to numerous thunderstorms are expected to develop ahead of the front
during the day as surface temperatures warm. It appears that a
marginal severe threat will develop during the mid to late afternoon
over much of the northwestern edge of the moist sector from the
Ark-La-Tex northeastward into the Ohio Valley.

...Sunday/Day 6 to Tuesday/Day 8...
On Sunday in the mid-levels, a 90 to 110 knot jet is forecast to
move into the northern U.S., as westerly flow remains over much of
the east-central U.S. A front is forecast to become quasi-stationary
from the Ozarks eastward into the southern Appalachians. Isolated to
scattered thunderstorms with a marginal severe threat may develop to
the south of the front during the afternoon.

On Monday and Tuesday, moisture advection is forecast to take place
from the central Plains into the Great Lakes, as mid-level flow
again becomes southwesterly. Moisture and instability should be
favorable for isolated severe storms Monday afternoon in areas that
heat up sufficiently. On Tuesday, models forecast a strong
upper-level system to eject northeastward into the south-central
U.S. If this scenario works out, a greater severe threat appears
possible Tuesday afternoon and evening over the southern and central
Plains. However, uncertainty is considerable at this range in the
forecast period due to a relatively wide spread in the model
guidance.

..Broyles.. 03/03/2026

= = =
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (1:2320/105)