Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0730 AM CDT Fri Sep 19 2025
Valid 191300Z - 201200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL PLAINS...
...SUMMARY...
Isolated severe thunderstorms may impact parts of southwestern
Nebraska into western and central Kansas late this afternoon and
evening, accompanied by some risk for severe hail and wind.
...Synopsis...
A weak upper trough/low will move eastward today from the northern
Plains to the Upper Midwest. An embedded mid-level shortwave trough
and speed maximum over eastern WY/western SD this morning will
rotate southeastward across parts of the central Plains this
afternoon and evening. Weak upper ridging will be maintained over
portions of the Southwest/Four Corners into the northern Great
Basin, with multiple low-amplitude perturbations forecast to spread
east-northeastward across these regions. At the surface, a weak low
over the eastern Dakotas should gradually fill through the day,
while a front stalls along/near the KS/NE border to the east of
modest lee cyclogenesis over the central High Plains.
...Central Plains...
It appears that increasing large-scale ascent associated with the
embedded shortwave trough and modestly enhanced west-northwesterly
jet may be sufficient to encourage isolated thunderstorms to develop
by late afternoon/early evening across parts of southwest NE into
western KS. This region should have a modestly moist low-level
airmass in place, with enough daytime heating forecast to support
around 1000-1500 J/kg of MLCAPE. Even though mid-level lapse rates
are not expected to become overly steep, strong deep-layer shear
should aid in convective updraft organization. There is still
considerable uncertainty with overall thunderstorm coverage this
afternoon/evening across the central Plains. Any thunderstorms that
can form and be sustained could produce isolated severe hail and/or
gusts as they spread southeastward across western/central KS through
the evening.
...Upper Midwest...
Modest west-southwesterly mid-level winds will be present today over
parts of the Upper Midwest on the eastern side of the upper-level
trough/low. Lapse rates aloft are forecast to remain rather poor,
which should limit the development of any more than weak instability
this afternoon. While scattered to numerous thunderstorms are
expected to develop later today, the overall thermodynamic/kinematic
environment appears too marginal to include low severe
probabilities.
...Southwest...
Showers and thunderstorms are ongoing this morning across parts of
central/eastern AZ into western NM and far west TX. This activity is
related to weak ascent aloft associated with minor perturbations
rotating through/around a weak upper ridge over the Southwest. Some
guidance shows potential for additional robust thunderstorm
development by late afternoon/early evening, likely aided by
orographic lift and other weak mid-level disturbances. Substantial
uncertainty exists regarding the intensity of these thunderstorms
later today owing to ongoing clouds/precipitation, lack of a notable
EML, and limited forecast instability/low-level lapse rates. Have
therefore not included any severe wind probabilities at this time.
..Gleason/Grams.. 09/19/2025
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