Storm Prediction Center Mesoscale Discussion 1774

   Mesoscale Discussion 1774
   NWS Storm Prediction Center Norman OK
   0439 PM CDT Thu Jul 24 2025

   Areas affected...portions of northern Illinois...northern
   Indiana...southern parts of Lower Michigan

   Concerning...Severe Thunderstorm Watch 540...

   Valid 242139Z - 242315Z

   The severe weather threat for Severe Thunderstorm Watch 540
   continues.

   SUMMARY...Scattered strong to severe thunderstorms should persist
   across portions of the OH Valley through the remainder of the
   evening, with severe gusts the main threat. Convective trends will
   be monitored for the need of a Severe Thunderstorm Watch issuance in
   southeast Lower MI.

   DISCUSSION...Scattered multicells and short bowing segments have
   been percolating in intensity over northern IL to far southwestern
   Lower MI over the past few hours. Multiple damaging gusts have been
   reported, some measured over 50 kts in magnitude. Though vertical
   wind shear remains modest across the southern Great Lakes (e.g.
   25-35 kts of effective bulk shear), over 2500 J/kg MLCAPE exist in
   some spots, which will encourage additional water-loaded downdrafts
   given 1.8-2.0 inch PWATs in place. Strong to severe gusts remain a
   concern through the remainder of the afternoon. It is unclear how
   far east the severe gust threat will persist. However, convective
   trends will continue to be monitored for the need of a Severe
   Thunderstorm Watch issuance should the severe threat persist.

   ..Squitieri/Mosier.. 07/24/2025

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...DTX...IWX...GRR...LOT...ILX...DVN...

   LAT...LON   40958974 42358664 42908537 43308366 43478258 43198237
               42778249 42478276 42218311 41988342 41858386 41488531
               41118643 40778738 40648804 40578921 40958974 

   MOST PROBABLE PEAK WIND GUST...55-70 MPH
   MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN