ACUS48 KWNS 260845
SWOD48
SPC AC 260844

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0344 AM CDT Mon Aug 26 2024

Valid 291200Z - 031200Z

...DISCUSSION...
An upper low is forecast to move across the Canadian Prairie and
north-central U.S. through the first half of the Day 4/Thursday
period, before being shunted a bit northeastward into Ontario due to
pronounced downstream ridging.  Timing differences amongst the
medium-range global models with the advance of this feature,
similarly result in positional differences with the surface front.
Thus, while some severe risk may manifest during the
afternoon/evening hours across the Upper Midwest region given a
likely-to-be-sufficient kinematic and thermodynamic environment
ahead of the front, no risk areas will be highlighted at this time.

Similarly on Day 5/Friday, timing differences are evident as upper
troughing and the associated surface front shift across the Upper
Great Lakes/Midwest region.  While some severe risk would again be
possible within this general region, too much positional uncertainty
exists for areal outlines.

Beyond Day 5, a gradual expansion of cyclonic flow aloft is forecast
across roughly the eastern half of the country -- though to
different degrees in the various models.  As this occurs, the more
favorably moist low-level airmass will gradually be suppressed
southward, south of the faster belt of flow aloft, and thus a
general decrease in severe risk is expected across the U.S. overall.
This trend should continue through the end of the period, as a
pronounced intrusion of Canadian air gradually spreads across the
eastern two-thirds of the country through Labor Day and beyond.

..Goss.. 08/26/2024

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