SPC AC 260550
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1250 AM CDT Tue Sep 26 2023
Valid 271200Z - 281200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
KENTUCKY...INDIANA...SOUTHWEST OHIO...AND MIDDLE TENNESSEE...
Thunderstorms producing a few strong gusts or marginally severe hail
will be possible across parts of the Ohio Valley into Middle
Tennessee on Wednesday.
An upper low and associated shortwave trough over the Pacific
Northwest Wednesday morning will weaken/fill rapidly as it sweeps
east across MT, with height falls overnight into the northern High
Plains. To the east, a weaker upper low will drift from IL into IN,
with little progress into OH and Lower MI.
At the surface, cool air with high pressure will extend from Quebec
southwestward across the Great Lakes and into the northern Plains,
as well as along the East Coast. A relatively weak surface trough
between the pressure ridges will exist across the OH Valley, where
westerly flow in the low levels may maintain moisture and
instability for scattered daytime storms.
Strong daytime heating will occur across the region, with steep
low-level lapse rates roughly from St. Louis to Louisville. Although
moisture will be meager with dewpoints struggling to exceed 60 F,
cool midlevel temperatures with the upper low will maximize
instability with around 750-1000 J/kg MLCAPE in spots. Wind shear
will be marginally favorable for a few longer-lived cells, but
storms should remain relatively disorganized as they redevelop from
IN into central KY and arcing southward toward Middle TN. The
favorable time of day may favor isolated marginal hail in the
strongest cells, and locally damaging gusts cannot be ruled out
given the deep mixed layers and sufficient instability.
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NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z