Mesoscale Discussion 1193
   NWS Storm Prediction Center Norman OK
   0717 PM CDT Sat Jul 11 2020

   Areas affected...eastern Iowa into central Illinois

   Concerning...Severe Thunderstorm Watch 359...

   Valid 120017Z - 120115Z

   The severe weather threat for Severe Thunderstorm Watch 359
   continues.

   SUMMARY...Damaging wind gusts and large hail will remain likely with
   a complex of strong thunderstorms moving into western Illinois this
   evening.

   DISCUSSION...Numerous reports of severe wind gusts and large hail
   have occurred across the western portions of WW359 over the last
   several hours. The cluster of multicell and occasional supercells is
   ongoing ahead of a mid-level shortwave trough and jet max across the
   upper Midwest and central Plains. Height falls ahead of the
   approaching trough will help to maintain the already destabilized
   airmass ahead of the ongoing storms. MLCAPE of 2500-3500 J/kg and
   30-40 kt of effective shear across Illinois will likely continue to
   support robust updraft development/ organization over the next
   several hours. Steep mid-level lapse rates around 8 C/km and deep
   updrafts from the strong buoyancy will support large hail growth
   with the stronger storms. However, it appears likely that upscale
   growth and storm interactions will shift the primary severe threat
   toward damaging winds later this evening. A few significant wind
   gusts may also be possible with any small bowing segments that can
   develop. 

   Earlier day convection across Indiana may serve to limit the
   eastward extent of the severe threat where convective overturning
   has taken place. However, a reservoir of deeper moisture and
   stronger buoyancy remains in place to the immediate south and west
   of the more stable air. Increasing ascent from the approaching
   trough and weak low-level warm advection may be sufficient to
   destabilize the airmass enough to support a continued severe threat
   later this evening. Convective trends will be monitored for a
   possible watch downstream of 359.

   ..Lyons/Hart.. 07/12/2020

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

   ATTN...WFO...IND...LOT...ILX...DVN...ARX...DMX...

   LAT...LON   42669214 40829218 39518747 41078775 41618844 42669214