ACUS01 KWNS 251250
SWODY1
SPC AC 251248
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0748 AM CDT Sun May 25 2025
Valid 251300Z - 261200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN PLAINS...
...SUMMARY...
Severe thunderstorms, including the risk for very large hail, swaths
of severe winds with isolated 75+ mph gusts, and a few tornadoes,
are expected across parts of the southern Plains this afternoon and
evening. Scattered severe thunderstorms with large hail and damaging
winds will also be a concern across the lower Mississippi Valley
into the Deep South.
...Synopsis...
A weak upper trough will advance slowly eastward today across the
Southwest and southern Rockies, while upper ridging gradually
becomes more suppressed over the southern/central Plains by a
low-amplitude shortwave trough moving northeastward from northern
Mexico. A belt of enhanced mid-level flow associated with upper
troughing over the Northeast is expected to remain mostly displaced
to the north of the warm sector in place across the Ozarks into the
lower MS Valley and Southeast. At the surface, a convectively
reinforced front extending eastward from a weak surface low over the
southern High Plains will likely serve as a focus for renewed severe thunderstorm development this afternoon and evening. The northward
advance of this front with eastward extent into the lower MS
Valley/Mid-South and TN Valley remains somewhat uncertain. But, most
guidance still shows it generally draped from northwest to southeast
across these regions by this afternoon.
...Central/Southern Plains into the Lower Mississippi Valley and
Southeast this Morning/Afternoon...
A 30-35 kt south-southwesterly low-level jet will continue to aid
mostly elevated thunderstorms across southern KS into the Ozarks
this morning. With strong deep-layer shear in place, some of this
convection may continue to pose an isolated threat for hail/wind
over the next few hours, even with greater low-level moisture and
related instability confined farther south along the
outflow-reinforced boundary. As filtered diurnal heating occurs
downstream of this morning activity, an increasingly unstable
airmass is likely to exist from parts of eastern OK into AR and the Mid-South/lower MS Valley, along and south of the front. Various
NAM/RAP forecast soundings across this region suggest that stronger
deep-layer shear will tend to remain to the north of the surface
boundary. Still, there will likely be sufficient shear to foster
some updraft organization, with both clusters and embedded supercell
structures possible.
One or more well organized clusters/bowing line segments may
eventually develop across the lower MS Valley/Mid-South vicinity
this afternoon/evening, possibly related to the ongoing convection
this morning across south-central KS and northeast OK/northwest AR.
Regardless of its origin, the overall environment should support at
least scattered severe/damaging winds and occasional large hail as
these thunderstorms spread east-southeastward through the afternoon
and early evening. Consideration was given to including higher wind probabilities across part of this region, but confidence was not
high enough in a more concentrated corridor of severe wind gusts to
do so at this time. Severe probabilities have been expanded
southward across the lower MS Valley to account for one or more
thunderstorm clusters with associated damaging wind threat spreading southeastward this evening into the early overnight hours, before
eventually weakening.
...Southern High Plains into the ArkLaTex this Afternoon through
Tonight...
A low-amplitude mid-level shortwave trough over northern Mexico this
morning will move northeastward across the southern High Plains by
this afternoon/evening. Ahead of this feature, ample daytime heating
will likely aid in the development of moderate to strong instability
by mid afternoon amid a moist low-level airmass. A surface front
will extend from eastern NM across northwest TX and the TX Panhandle
into parts of western/central OK, with a dryline extending southward
from the front across west TX. Both of these surface boundaries will
likely prove instrumental, in combination with modest large-scale
ascent associated with the shortwave trough, to focus intense
thunderstorm development later today. While mid/upper-level winds
are not expected to be overly strong, veering and gradual
strengthening with height should support around 30-45 kt of
deep-layer shear. Stronger shear is forecast near the front.
Convective temperatures will likely be reached by 20-22Z, and
explosive thunderstorm development is expected in this time frame
across west/northwest TX along the front and dryline.
A mix of supercells and clusters will likely form and spread
east-northeastward across the southern High Plains through the late
afternoon and early evening. Very large hail (2-3 inches in
diameter) will be possible with any initial supercells given
favorably steep mid-level lapse rates and relatively long/straight
hodographs at mid/upper levels. By early evening, consolidation into
a bowing complex appears likely across northwest TX and vicinity. An
increasing threat for scattered to numerous severe winds will exist
with this cluster as it develops generally eastward into western
north TX and southwest OK through the evening. Given steepened
low-level lapse rates and the presence of strong to locally extreme instability, some wind gusts of 75+ mph appear possible with the
bowing cluster. The potential for supercells to develop separately
farther east along the front in western/central OK remains unclear.
If thunderstorms can form here, they would likely become severe
quickly, and pose a threat for very large hail. Some risk for a few
tornadoes may also exist this evening (either embedded with the bow
or with semi-discrete supercells) as a southerly low-level jet and
related 0-1 km SRH gradually strengthens. A continued threat for severe/damaging winds may continue into the early overnight hours
across parts of OK and north/central TX. Severe probabilities have
been expanded southward some to account for latest guidance trends
showing the potential for the bow to persist with some intensity
farther south/east in TX.
A somewhat separate area of at least isolated supercell potential is
also evident across northeast to east-central NM this afternoon in a
modest low-level upslope flow regime along and north of the front.
Large hail should be the main threat with this activity. The
eastward extent of the severe threat will likely be confined by
weaker instability into the OK Panhandle and northern TX Panhandle.
...Florida...
Compared to the prior couple of days, mid/upper-level winds appear
somewhat weaker across the FL Peninsula today. Mid-level
temperatures are also slightly warmer per area 12Z soundings. Even
so, another day of scattered thunderstorm development is anticipated
over much of the FL Peninsula, with various sea breezes acting as
foci for initiation. Moderate instability coupled with modest
deep-layer shear may still support an isolated threat for marginally
severe hail and gusty winds with the stronger cores that can develop
this afternoon.
..Gleason/Leitman.. 05/25/2025
$$
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