ACUS01 KWNS 081221
SWODY1
SPC AC 081219

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0719 AM CDT Mon Sep 08 2025

Valid 081300Z - 091200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE CENTRAL AND SOUTHERN HIGH PLAINS...

...SUMMARY...
Isolated large to very large hail and severe gusts are forecast over
portions of southwestern Kansas, northwest Oklahoma, and the Texas
Panhandle late this afternoon into the evening.

...Central/Southern High Plains...
Morning water-vapor imagery shows a mid-level shortwave trough
moving east-southeast across the central High Plains.  Scattered
showers/thunderstorms are ongoing from northern KS into the
northeast TX Panhandle associated with low-level warm-air advection.
This convection will likely remain weak and slowly shift
east-southeast before largely diminishing 18-21z.  As the
aforementioned disturbance moves into central KS by late afternoon,
a differential heating zone arcing northward in wake of the
convection will intersect with a moisture plume extending northward
from west TX into the TX/OK/KS border region.

Heating will contribute to a moderate to very unstable airmass
(2000-3000 J/kg MLCAPE) from the TX Panhandle into southwest KS.
Weak low-level convergence should prove instrumental in convective
initiation late this afternoon into the early evening.  Isolated to
scattered thunderstorms are probable with the locally highest risk
for severe in the northeast TX Panhandle into adjacent parts of
northwest OK and southwest KS.  Model forecast hodographs are
elongated, which will favor supercells and hail growth given the
magnitude of buoyancy.  Large to very large hail (1 to 3 inches in
diameter) is possible with the stronger storms.  A brief tornado
cannot be ruled out during the early evening transition when
low-level shear increases.  Severe gusts may also accompany the
stronger cores through much of the evening before this activity
diminishes 03-05z.

...Upper MS Valley Vicinity...
Northern stream short-wave trough is forecast to dig southeast
across southern MB/ND into the upper Red River region by early
evening.  This should aid in the development and intensification of
a southwesterly LLJ forecast to overspread the Upper Midwest during
the period.  Large-scale forcing favors elevated convection along
the nose of this jet, especially across the Arrowhead of MN/Lake
Superior.  Relatively steeper lapse rates may permit a few robust
updrafts to evolve shortly after peak heating with an attendant risk
for isolated marginally severe hail.

...Central OR...
A mid- to upper-level shortwave trough located to the west of the
northern CA coast will move east-northeast into southwest OR by late
tonight.  Heating coupled with large-scale ascent associated with
the disturbance will favor scattered thunderstorms developing this
afternoon near and east of the Cascades.  Forecast soundings show
500-mb temperatures around -15 deg C and weak buoyancy.  A couple of
the stronger updrafts may yield a near-severe hail threat (0.50-1.00
inch in diameter) for a few hours.

..Smith/Broyles.. 09/08/2025

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