Storm Prediction Center Mesoscale Discussion 1683

   Mesoscale Discussion 1683
   NWS Storm Prediction Center Norman OK
   0830 PM CDT Mon Jul 20 2026

   Areas affected...west-central Illinois

   Concerning...Severe Thunderstorm Watch 504...

   Valid 210130Z - 210300Z

   The severe weather threat for Severe Thunderstorm Watch 504
   continues.

   SUMMARY...The potential for locally damaging wind gusts will
   continue and may develop south of the watch area. Convective trends
   are being monitored for a possible downstream watch.

   DISCUSSION...As of 0115Z, a small cluster of thunderstorms was
   centered over Hancock and McDonough Counties, IL, with a system
   motion of 325/25 kt. While distant from the radar, base velocity
   data from KDVN show 60+ kt outbound values at ~7 kft above the
   ground. Latest objective fields indicate poor low-level lapse rates
   and increasing convective inhibition, which are likely limiting the
   potential for the stronger winds aloft from reaching the ground.
   These factors are expected to limit the potential for a more robust
   damaging wind threat; however, isolated wind gusts of 60-65 mph will
   remain possible for the next several hours.

   ..Mead.. 07/21/2026

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

   ATTN...WFO...ILX...LSX...DVN...

   LAT...LON   39829105 40139147 40589147 40769081 40069032 39779059
               39829105 

   MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
   MOST PROBABLE PEAK WIND GUST...55-70 MPH
   MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN