(All days are valid from 12 UTC - 12 UTC the following day)
Note: A severe weather area depicted in the Day 4-8 period indicates 15%, 30% or higher probability for severe thunderstorms within 25 miles of any point.
PREDICTABILITY TOO LOW is used to indicate severe storms may be possible based on some model scenarios. However, the location or occurrence of severe storms are in doubt due to: 1) large differences in the deterministic model solutions, 2) large spread in the ensemble guidance, and/or 3) minimal run-to-run continuity.
POTENTIAL TOO LOW means the threat for a regional area of organized severe storms appears unlikely (i.e., less than 15%) for the forecast day.
ZCZC SPCSWOD48 ALL
ACUS48 KWNS 260843
SPC AC 260843
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0343 AM CDT Tue Sep 26 2023
Valid 291200Z - 041200Z
For most of the day 4-8 period, an upper trough is forecast to
affect much of the western CONUS, making little progress eastward as
the trough becomes a large cut-off low over the Great Basin, and an
upper high remains over the lower MO/mid MS Valley region.
A surface high from the Midwest into the Northeast will be a primary
mitigating factor for severe weather potential, as moisture return
across the plains will be minimal as a result. Pockets of strong
instability > 1000-1500 J/kg are forecast to exist primarily over
the northern Plains/Upper MS Valley, well ahead of the western
trough. While scattered thunderstorms will be possible from parts of
MT eastward across parts of the Dakotas and MN from Friday through
at least Sunday, neither instability nor shear would appear to favor
any widespread severe potential, although isolated hail or wind
reports may occur during this time frame.
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