Storm Prediction Center Mesoscale Discussion 1949

   Mesoscale Discussion 1949
   NWS Storm Prediction Center Norman OK
   0904 AM CDT Wed Aug 12 2026

   Areas affected...northern and central Illinois into western Indiana

   Concerning...Severe Thunderstorm Watch 574...

   Valid 121404Z - 121600Z

   The severe weather threat for Severe Thunderstorm Watch 574
   continues.

   SUMMARY...Damaging winds with gusts up to 75 mph are expected to
   continue with an ongoing bow echo. The severe weather threat may
   develop east of the watch area by 1530Z, likely requiring a new
   severe thunderstorm watch.

   DISCUSSION...The northern extension of an MCS has sustained a bowing
   structure over northern IL with an eastward system motion of around
   40 kt. An outflow boundary associated with an area of thunderstorms
   farther east extends from the vicinity of the bow echo
   south-southeast through eastern IL into southwest IN. The presence
   of that boundary may result in the MCS turning more to the southeast
   over the next hour to two, fueled by a strongly unstable
   environment, per the 12Z DVN sounding.

   The current DVN VWP is sampling 35-50 kt west-northwesterly winds in
   the 1-6 km layer, which are oriented largely perpendicular to the
   bow, likely maintaining a robust rear-inflow jet. As such, damaging
   winds are expected to continue with gusts up to 75 mph possible as
   the system advances toward northwest and west-central IN.
   Extrapolation of the current motion takes it to the eastern edge of
   the watch by 1530Z, likely requiring an additional watch.

   ..Mead.. 08/12/2026

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

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

   LAT...LON   41909007 41758803 41268700 40498663 40088648 39578665
               39578722 39588774 39848855 40268968 40819028 41499046
               41909007 

   MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
   MOST PROBABLE PEAK WIND GUST...65-80 MPH
   MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN