Subj : DAY1SVR: Day 1 Convective Outlook
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Thu Aug 21 2025 00:41:36

ACUS01 KWNS 210041
SWODY1
SPC AC 210039

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0739 PM CDT Wed Aug 20 2025

Valid 210100Z - 211200Z

....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF CENTRAL MONTANA INTO NORTHERN NORTH DAKOTA AND ACROSS PORTIONS OF
THE LOWER MISSISSIPPI VALLEY...

....SUMMARY...
Isolated severe thunderstorms are possible from central Montana into
northern North Dakota tonight. A few wind gusts may also be noted
with storms over the lower Mississippi Valley early this evening.

....01z Update...

Early-evening water-vapor imagery depicts an upper trough extending
across southeast BC into the northern Rockies. This feature is
forecast to advance to near the AB/SK border by the end of the
period, with modest mid-level height falls expected across northeast
MT into ND. As 500mb speed max strengthens over southern SK later
tonight some increase in LLJ should be noted across western ND -
just ahead of the progressive surface front. Isolated robust
convection has developed ahead of the short wave from southwest SK
into central MT. This activity may continue to generate gusty winds
and hail, but new updrafts are expected downstream across western ND
with time. Vis imagery suggests high-based updrafts are deepening
across southeast MT into southwest ND, and isolated severe may
ultimately evolve along the northern edge of this steep lapse rate
plume, immediately ahead of the front.

Boundary-layer heating was instrumental in scattered-widespread
convection across the northern Gulf States this afternoon. While
considerable convective overturning has occurred, a pocket of modest
instability persists across much of LA. Cluster of strong-locally
severe thunderstorms will drift south across this region over the
next several hours. Boundary-layer cooling will negate updraft
intensity by mid evening.

...Darrow.. 08/21/2025

$$

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