Storm Prediction Center Mesoscale Discussion 1974

   Mesoscale Discussion 1974
   NWS Storm Prediction Center Norman OK
   1103 PM CDT Thu Aug 13 2026

   Areas affected...eastern Iowa...northern/central Illinois...and
   central Indiana

   Concerning...Severe potential...Watch possible 

   Valid 140403Z - 140600Z

   Probability of Watch Issuance...40 percent

   SUMMARY...Occasional stronger storms may produce small hail and
   gusty winds overnight.

   DISCUSSION...Thunderstorm activity is increasing within the warm
   advection regime across portions of eastern Iowa into northern
   Illinois/Indiana. This activity is ongoing north of a surface front
   extending from the central Plains across southern Illinois into
   southern Illinois/northern Kentucky. The air mass near the ongoing
   convection is only marginally unstable located on the northern
   fringes of more moderate to strong instability further south across
   southern Illinois into portions of southern Indiana/northern
   Kentucky. Forecast soundings suggest the presence of a fairly strong
   cap at the base of the EML across much of the region of greater
   buoyancy, which will likely inhibit surface based convection. 

   Generally boundary parallel flow will likely produce training storms
   overnight, with little organized severe potential. Later into the
   overnight/early morning, the low-level jet will increase into
   Illinois/Indiana. Should a cluster be able to develop and drop
   southward, there could be some damaging wind potential into the
   morning. A few instances of gusty winds and small hail will be
   possible with stronger cores. For now, confidence in a more
   organized severe risk remains low but trends will be monitored
   overnight.

   ..Thornton/Hart.. 08/14/2026

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

   ATTN...WFO...ILN...LMK...IWX...IND...LOT...ILX...LSX...DVN...

   LAT...LON   41788993 41859141 41379201 40489155 40219102 39588904
               38778560 38678459 39108416 39748424 40288456 41248686
               41638908 41788993 

   MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH
   MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN