Storm Prediction Center Mesoscale Discussion 1154

   Mesoscale Discussion 1154
   NWS Storm Prediction Center Norman OK
   1222 PM CDT Tue Jun 16 2026

   Areas affected...eastern Illinois...northern Indiana...lower
   Michigan

   Concerning...Severe potential...Watch likely 

   Valid 161722Z - 161915Z

   Probability of Watch Issuance...80 percent

   SUMMARY...Thunderstorm activity to increase through the afternoon
   with potential for damaging winds, large hail, and a couple of
   tornadoes.

   DISCUSSION...Thunderstorm activity is increasing across portions of
   lower Michigan ahead of a surface low/cold front located across
   Wisconsin. This activity will pose some risk for marginally severe
   hail in the near term.

   Additional development is expected back west near the cold front
   across Illinois by early afternoon. While thermo profiles ahead of
   the front remain meager, temperatures are steadily cooling aloft
   with the approach of the upper low. This will likely modify profiles
   quickly through the afternoon. Shear profiles support initial
   supercell modes along the front this afternoon across Illinois into
   northern Indiana and far southern Michigan. Given the steepening
   lapse rates and strong deep layer shear, large hail and damaging
   wind will be possible. Curved low-level hodographs will support some
   enhancement of SRH across northern Indiana into southern Michigan
   with potential for a tornado or two. Upscale growth is expected with
   time, with a shift in the main threat to become damaging wind with
   time. A watch will likely be needed for parts of the area to cover
   these potential threats in the next couple of hours.

   ..Thornton/Hart.. 06/16/2026

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

   ATTN...WFO...DTX...APX...IWX...GRR...IND...LOT...ILX...

   LAT...LON   40468891 40918847 41738756 44738412 44288294 43228273
               42218353 40848509 39848701 39818767 39888845 40468891 

   MOST PROBABLE PEAK TORNADO INTENSITY...85-110 MPH
   MOST PROBABLE PEAK WIND GUST...55-70 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN