ACUS02 KWNS 210617
SWODY2
SPC AC 210616

Day 2 Convective Outlook CORR 1
NWS Storm Prediction Center Norman OK
0116 AM CDT Sun Sep 21 2025

Valid 221200Z - 231200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
SOUTHWEST/SOUTH-CENTRAL KANSAS...WESTERN/CENTRAL OKLAHOMA...AND THE
EASTERN TEXAS/OKLAHOMA PANHANDLES...

...SUMMARY...
Scattered severe thunderstorms will be possible on Monday across
portions of the central and southern High Plains.

...Synopsis...
On Monday, a mid-level trough will move from the upper
Midwest/Missouri Valley to the Great Lakes/Ohio Valley during the
period. Farther west, a more complicated pattern will develop as a
ridge builds into the Pacific Northwest. As this ridge builds, a
mid-level jet streak will be shunted south across the central
Rockies. This will deepen a mid-level low with a closed circulation
likely developing across the central High Plains region by 12Z
Tuesday. In addition, a closed low will persist off the southern
California coast for much of the period. High pressure will be
present across much of the western CONUS with weak lee troughing
along the central and southern High Plains. The surface pattern will
be somewhat less defined farther east with a weak remnant front
likely through the Upper Midwest to the western Great Lakes. High
pressure will dominate areas east of the Appalachians.

...Central Plains...
Moderate to strong instability will develop by Monday afternoon in
the wake of a morning MCS across Oklahoma/Kansas. Forecast soundings
show a strongly capped airmass across Kansas/Oklahoma and given the
relatively weak forcing amid modest height falls, do not expect much
thunderstorm development until after 00Z. After this time, the
mid-level trough will start to overspread the Plains with a
strengthening low-level jet potentially approaching 50 knots.
Cooling temperatures aloft and strong isentropic ascent should
result in thunderstorm development after sunset Monday evening. Seep
mid-level lapse rates and strengthening effective shear (40 to 50
knots) will support the potential for supercells with some hail
threat. As upscale growth continues, the severe wind threat should
increase and continue into the overnight period into portions of
central/northern Oklahoma.

...NE/IA to Lake Michigan...
Diurnal thunderstorm development is possible along a diffuse frontal
zone from Nebraska to southern Wisconsin. Modest lapse rates and
moderate instability along this zone will support some multicells
capable of some hail or damaging wind gusts. However, mostly weak
deep-layer shear (20 knots) and weak upper forcing should keep the
overall threat along this zone relatively isolated.

...Tennessee Valley to the eastern Great Lakes...
A weak mid-level shortwave trough is forecast to move through the
Ohio Valley on Monday with moderate instability forecast ahead of
it. An uncapped airmass and some moderate upper-level support in a
broader zone of weak, but persistent isentropic ascent should
support scattered thunderstorm development. Lapse rates will be
poor, but modest effective shear amid 30 to 35 knots of mid-level
flow may support some organized multicells capable of damaging wind
gusts Monday afternoon/evening.

..Bentley.. 09/21/2025

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