ACUS11 KWNS 121945
SWOMCD
SPC MCD 121944=20
MIZ000-INZ000-ILZ000-122145-

Mesoscale Discussion 1935
NWS Storm Prediction Center Norman OK
0244 PM CDT Tue Aug 12 2025

Areas affected...southern/eastern IL...western/northern
IN...southwest Lower MI

Concerning...Severe potential...Watch unlikely=20

Valid 121944Z - 122145Z

Probability of Watch Issuance...5 percent

SUMMARY...Sporadic strong gusts of 45-60 mph and generally small
hail to 1 inch in diameter will be possible with a broken band of
thunderstorms slowly progressing from Illinois into parts of Indiana
and Lower Michigan. A Severe Thunderstorm Watch is not expected.

DISCUSSION...Along a band of low-level confluence, thunderstorms
have become increasingly numerous from southeast MO into southwest
Lower MI. With surface temperatures of 86-91 F common ahead of this
activity, to the west/north of separate convective outflow in
central IN, potential for sporadic downbursts exists amid weak
lower-level flow. Area VWP data indicate 0-6 km shear around 20 kts
across IL into IN, to around 25 kts in southwest Lower MI. Speed
change with height is largely concentrated in the mid to upper
portion of the buoyancy profile. This suggests small to marginally
severe hail may accompany the strongest updrafts. Loose multicell
clustering may support a localized, marginal severe wind threat.
Based on latest trends, this could be centered in corridors across
the IL/IN/MI border area with ongoing storms near/south of
Chicagoland and separately to the east-northeast of storms near/east
of St. Louis.

..Grams/Smith.. 08/12/2025

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!5hXkCudAjTNjcOvTHrETxWhmzzYsmCbqMt9SaOw3VhC-029B8P8ykCq0fay5ztPW1qquZ1P5W= d0AvqgWe7lofSMfk68$ for graphic product...

ATTN...WFO...IWX...GRR...IND...LOT...ILX...LSX...

LAT...LON 42588622 42818602 42838532 42298496 41578551 40638690
38888858 38738939 38868968 39388949 40258868 41058804
41728729 41918683 42358633 42588622=20

MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN


=3D =3D =3D
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