Subj : DAY48SVR: Nws Storm Prediction Center Norman Ok
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Thu Sep 18 2025 14:10:34

ACUS48 KWNS 181410
SWOD48
SPC AC 181409

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0909 AM CDT Thu Sep 18 2025

Valid 211200Z - 261200Z

....DISCUSSION...
An upper shortwave trough is forecast to move across the northern
Rockies on Day 4/Sun while low-amplitude, broad upper troughing
persists across the central portion of the CONUS. By Day 5/Mon, the
northern Rockies upper trough is expected to rapidly deepen as it
overspread the plains. Rich boundary layer moisture if forecast to
be in place across portions of the southern/central Plains into the
MS Valley as a strong cold front moves across parts of the Plains.
While the timing of the upper trough ejecting into the Plains is
uncertain, some severe potential could develop on Day 5/Mon across
the southern/central Plains toward the Mid/Lower MO Valley.
Uncertainty remains too high to include 15 percent probabilities at
this time however.

Beyond Day 5/Mon, uncertainty increases as large spread among model
guidance persists with regard to the evolution of a developing upper
low somewhere over the mid-section of the CONUS into Day 8/Thu.
Severe potential is uncertain, and the overall pattern may favor
heavy rain over organized severe heading into Day 6/Tue, but model
trends will continue to be monitored.

...Leitman.. 09/18/2025

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