Mesoscale Discussion regarding Severe Thunderstorm Watch

   Mesoscale Discussion 1787
   NWS Storm Prediction Center Norman OK
   0740 AM CDT Sun Aug 18 2019

   Areas affected...southeast Wisconsin...
   northeast    Illinois...northwest Indiana
   ...and southwest Michigan

   Concerning...Severe Thunderstorm Watch 597...

   Valid 181240Z - 181445Z

   The severe weather threat for Severe Thunderstorm Watch 597
   continues.



   SUMMARY...Thunderstorms continue this morning across the region.
   Moderate instability and sufficient shear should continue to support
   a severe threat this morning.

   DISCUSSION...Initial line of thunderstorms has weakened considerably
   this morning as increasing precipitation ahead of the line --
   stemming from thunderstorms that developed south-southwest of
   Chicago -- has acted to stabilize the airmass across north-central
   Illinois and southern Wisconsin. The strongest thunderstorm cluster
   from this original band of storms is currently located across
   southeast Wisconsin and will have the potential to pose a severe
   threat for another couple hours before moving east over Lake
   Michigan.

   As previously mentioned, additional thunderstorms developed to the
   south-southwest of Chicago, ahead of the original line of storms.
   These thunderstorms are within a better severe thunderstorm
   environment than those to the north given less convective coverage
   allowing most-unstable CAPE values to approach 2000 J/kg, and thus
   have a greater potential to pose a severe wind or hail threat. At
   present, these storms will move across the greater Chicago metro
   over the next 1-2 hours, with hail and wind threats likely. These
   storms will continue east-northeast through the morning, eventually
   moving over Lake Michigan.
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