Areas affected...the Mississippi River Valley into Illinois

   Concerning...Severe Thunderstorm Watch 537...

   Valid 190428Z - 190630Z

   The severe weather threat for Severe Thunderstorm Watch 537

   SUMMARY...The threat of hail and locally severe gusts continues, and
   may eventually affect areas south of WW 537. While local watch
   extensions in space may need to be considered later tonight,
   additional watches are not anticipated at this time.

   DISCUSSION...Several clusters of storms persist across the region,
   with the strongest activity over western IL near the MS River. Other
   sporadic cores have developed farther northwest into southeast IA,
   with indications of severe hail.

   Given the cooling boundary layer, effective parcels are somewhat
   elevated, with 925-850 mb winds out of the west. While still
   unstable, this air mass may dry a bit aloft as seen in water vapor 
   trends. In the near term, existing clusters of storms may pose a
   hail or wind threat, aided by moderate northwest flow aloft.
   However, the combination of drying midlevels as well as cooling low
   levels may result in increasing CIN, and gradually decreasing storm