(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.
Forecast Discussion
ZCZC SPCSWOD48 ALL
ACUS48 KWNS 230815
SPC AC 230815
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0315 AM CDT Wed Apr 23 2025
Valid 261200Z - 011200Z
...DISCUSSION...
...Days 5-7/Sun-Tue -- Great Plains to the Midwest...
Forecast guidance is in good agreement that a deepening upper trough
over the western states will eject eastward across the Plains and
Midwest early next week. Beginning Day 5/Sun, the upper trough will
extend from the central Rockies to the Southwest, with a belt of
strong southeasterly flow emerging over the central/southern High
Plains Sunday night. Surface lee low development is forecast over
the northern/central Plains Sunday afternoon, with the low moving
into SD/NE by Monday morning. Southerly low-level flow will
transport ample moisture northward across the Plains and Mid-MO
Valley on Sunday, with a sharpening dryline extending southward from
western NE into western TX. Some severe potential could develop
along the dryline and near the surface low/triple point. However,
forecast soundings maintain strong capping and any convective
development could be rather sparse. For now, this will preclude
severe probabilities for Day 5/Sun.
On Day 6/Mon, the upper trough will continue eastward, moving into
the Plains by Tuesday morning. Ahead of the trough, a belt of strong
southwesterly flow aloft will extend from OK into the Upper Midwest.
A deepening surface low over SD will shift east/northeast through
the period, with a trailing cold front shifting east/southeast
across the Plains. Rich boundary layer moisture within a moderate to
strongly unstable airmass and favorable shear parameter space will
support an all-hazards severe weather episode across a fairly broad
area from OK to MN/WI Monday afternoon into Monday night.
Severe potential is likely to continue into Day 7/Tue, though some
differences within medium range guidance with the evolution of the
upper trough and key surface features does result in a bit more
uncertainty compared to Monday, especially on the eastward extent of
severe potential. Nevertheless, strong forcing atop a broad warm
sector ahead of an eastward advancing cold front will continue to
support severe potential from northeast Texas into Lower MI.
..Leitman.. 04/23/2025
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