Subj : DAY48SVR: Nws Storm Prediction Center Norman Ok
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Thu Sep 11 2025 08:55:43

ACUS48 KWNS 110855
SWOD48
SPC AC 110854

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0354 AM CDT Thu Sep 11 2025

Valid 141200Z - 191200Z

....DISCUSSION...
Model guidance is in fairly good agreement that the upper trough
over the central US will continue to lift northeastward into the
northern Plains and Upper Midwest through early next week. This will
drag a surface low and cold front slowly eastward with seasonably
high moisture in place. The low will begin to fill as it also lifts
into southern Canada. Scattered to numerous thunderstorms appear
likely over the Northern Plains and Upper Midwest, and along the
trailing front over the southern/central Plains each afternoon, as
increasingly meridional flow will parallel the slow moving cold
front. This will favor continued storm development/training along
the boundary with limited air mass destabilization/recovery.
Mid-level lapse rates should also weaken as the upper trough begins
to fill. While some marginal severe risk is evident over the
northern Plains near the low and front, mainly D4/Sunday,
significant uncertainty exists regarding boundary-layer
destabilization and its impacts on severe potential through
D5/Monday.

By D6/Tuesday, mid-level ridging behind the trough is forecast to
temporarily strengthen, weakening upper-level flow across the CONUS.
A second upper trough over the northern Rockies will begin to
approach behind the central US ridge, while a cutoff low develops
over the Southeast. This should limit broader overlap of instability
and stronger mid-level flow across much of the CONUS. Widespread
severe weather appears unlikely through next week.

...Lyons.. 09/11/2025

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