Storm Prediction Center Mesoscale Discussion 1925

   Mesoscale Discussion 1925
   NWS Storm Prediction Center Norman OK
   1142 AM CDT Tue Aug 11 2026

   Areas affected...northeast Illinois into far southwest lower
   Michigan and northern and central Indiana

   Concerning...Severe Thunderstorm Watch 563...565...

   Valid 111642Z - 111845Z

   The severe weather threat for Severe Thunderstorm Watch 563, 565
   continues.

   SUMMARY...Damaging winds with significant gusts up to 75-85 mph are
   expected to continue with the ongoing bow echo. Brief tornadoes are
   also possible.

   DISCUSSION...An intense bow echo with a history of 85-95+ mph wind
   gusts across Chicagoland has shifted into far northwest IN as of
   1635Z. System movement is east at 55 to 60 kt. Considerable
   downstream convection present from the vicinity of the bow echo to
   north of Muncie has hindered daytime heating and resultant air mass
   destabilization within the inflow region of the bow echo.
   Nonetheless, the presence of an organized cold pool with an intense
   rear-inflow jet will support the continuation of damaging winds with
   significant gusts up to 75-85 mph for at least the next hour or two
   across portions of northern IN and perhaps far southwest lower MI.
   Brief tornadoes are also possible, especially with mesovortices
   forming near or north of the apex of the bow.

   Some recent CAM guidance suggests that a longer-duration significant
   wind threat could materialize within the southern flank of the bow
   echo and preceding convective band over central into southeast IN.
   That scenario appears plausible given the influx of a strongly
   unstable air mass from central IL into the region.

   ..Mead.. 08/11/2026

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

   ATTN...WFO...IWX...IND...LOT...ILX...

   LAT...LON   40898785 41428750 41698735 41848649 41828585 41638518
               40958502 40538500 40268510 40088535 39968574 39878640
               40358759 40898785 

   MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
   MOST PROBABLE PEAK WIND GUST...75-90 MPH
   MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN