Subj : DAY1SVR: Day 1 Convective Outlook
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Tue Sep 09 2025 19:42:13

ACUS01 KWNS 091942
SWODY1
SPC AC 091940

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0240 PM CDT Tue Sep 09 2025

Valid 092000Z - 101200Z

....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
EASTERN COLORADO...WESTERN KANSAS...AND THE OKLAHOMA/TEXAS
PANHANDLES...

....SUMMARY...
Widely scattered severe storms are possible over the central and
southern High Plains late this afternoon and evening.

....20z Update - Central/Southern High Plains...

The Slight risk (level 2 of 5) has been expanded southward to
include southwest KS and portions of the OK/TX Panhandles. This
change is based on latest modified RAP/NAM/HRRR/RRFS forecast
soundings, CAMs trends, as well as observation trends.

Temperatures have warmed into the upper 80s to low 90s F across the
region, nearing convective temperatures. Visible satellite imagery
shows cumulus developing in southeast CO within modest low-level
upslope flow, with minor convergence along the theta-e gradient and
surface trough from the northeast TX Panhandle toward the CO/KS
border. Isolated to widely scattered thunderstorms are expected to
develop by late afternoon and spread east/southeast into this
evening.

Vertically veering wind profiles, with forecast hodographs becoming
elongated/straight above 1-2 km, will support supercells. Steep low
and midlevel lapse rates and 1000-2500 J/kg MLCAPE values amid
favorable shear will favor large hail, with some potential for
stones greater than 2 inch diameter possible. Strong gusts may also
accompany stronger convection.

...Leitman.. 09/09/2025

..PREV DISCUSSION... /ISSUED 1121 AM CDT Tue Sep 09 2025/

....Central and Southern High Plains...
The upper ridge axis will remain over the Rockies today, with
northwest flow aloft across the Plains states.  High-based
thunderstorms are expected to develop off the high terrain of
central CO and northern NM by mid-afternoon, while isolated cells
form over a remnant boundary over eastern CO/western KS.  Backed
low-level winds, steep low and mid-level lapse rates, and CAPE
values ranging from 1000-2500 J/kg will promote a risk of a few
severe storms through the afternoon.  Large hail appears to be the
main concern, with gusty/damaging winds also possible in the
strongest cells.  Activity may persist through much of the evening
as it progresses eastward into an increasingly moist boundary layer
air mass.  12z CAMs show a consistent signal of multiple rounds of
storms affecting parts of eastern CO/western KS, so have added a
small SLGT risk for this region.

$$

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