Storm Prediction Center Mesoscale Discussion 2237

   Mesoscale Discussion 2237
   NWS Storm Prediction Center Norman OK
   0901 PM CDT Fri Sep 04 2026

   Areas affected...parts of southeastern Wisconsin...northeastern
   Illinois...southwestern Lower Michigan...northern Indiana and
   northwestern Ohio

   Concerning...Severe potential...Watch possible 

   Valid 050201Z - 050500Z

   Probability of Watch Issuance...40 percent

   SUMMARY...Initially scattered intensifying thunderstorm development,
   posing some risk to produce marginally severe hail and locally
   strong surface gusts, is possible through 10 PM-midnight.  There
   appears potential for activity to eventually consolidate and evolve
   into an organized cluster with increasing risk to produce a swath of
   strong to severe surface gusts later this evening or overnight. 
   Trends are being monitored for the possibility of a severe weather
   watch.

   DISCUSSION...An apparent mesoscale cyclonic vorticity center,
   associated with an earlier small cluster of storms over northeastern
   Iowa, is now approaching areas to the north-northwest of Rockford IL
   with a renewed increase in convective development slowly underway. 
   This appears generally focused near and just to the warm side of a
   quasi-stationary/slow moving low-level baroclinic zone extending
   east-southeastward across southern portions of Lake Michigan/Lower
   Michigan/northern Indiana and northwestern Ohio.  Downstream, to the
   cool side of the frontal zone, low-level warm advection also appears
   to be contributing to a gradual increase in convective development.

   Thermodynamic profiles along this zone are relatively warm, but with
   high low-level moisture content and characterized by at least
   modestly steep lower/mid-tropospheric lapse rates supporting large
   CAPE.  Coupled with favorable shear beneath modest northwesterly
   mid-level flow along the southwestern periphery of the westerlies,
   the environment appears conducive to gradually increasing and
   intensifying thunderstorm development over the next few hours.  This
   may eventually consolidate and organize into a cluster with
   increasing potential to produce damaging surface gusts later this
   evening across southern portions of the Great Lakes region, or
   overnight into the middle Ohio Valley.

   ..Kerr/Smith.. 09/05/2026

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

   ATTN...WFO...DTX...IWX...GRR...LOT...MKX...

   LAT...LON   42858882 42868609 42398464 41898396 41248427 40938483
               40898503 40918610 41338767 41988920 42298884 42858882 

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