Mesoscale Discussion 1348
   NWS Storm Prediction Center Norman OK
   0738 PM CDT Thu Jun 29 2023

   Areas affected...Parts of southern IL...southern IN...and western KY

   Concerning...Severe Thunderstorm Watch 420...

   Valid 300038Z - 300245Z

   The severe weather threat for Severe Thunderstorm Watch 420
   continues.

   SUMMARY...Risk of large hail and perhaps locally severe gusts
   continues across parts of southern IL and IN this evening, and could
   persist for another few hours. A new watch issuance is not currently
   expected upon the expiration of WWs 417 and 420.

   DISCUSSION...Latest water vapor imagery depicts a low-amplitude
   shortwave impulse overspreading parts of central IL/IN this evening
   -- accompanied by 60-70 kt of midlevel flow (per regional VWP data).
   A strengthening low-level jet impinging on a remnant cold pool over
   southern IL/IN is favoring regenerative convection along/atop the
   outflow-cooled air. While surface observations and RAP forecast
   soundings suggest this activity should remain elevated given the
   increased boundary-layer stability, 70-80 kt of effective shear is
   still favoring semi-discrete supercells capable of large hail. And,
   given the potential for strong midlevel mesocyclones which could
   locally modify the near-storm environment, locally damaging gusts
   cannot be entirely ruled out. With a reservoir of elevated
   instability and the aforementioned deep-layer shear, the severe
   threat could continue for a few more hours. Currently, a new watch
   issuance is not expected upon the expiration of Severe Thunderstorm
   Watches 417 and 420 given the limited areal coverage and uncertainty
   on convective intensity, though convective trends will be monitored.

   ..Weinman/Hart.. 06/30/2023

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

   ATTN...WFO...LMK...IND...PAH...ILX...LSX...

   LAT...LON   37878793 38348868 38598877 38788873 38998847 39048820
               38738730 38538675 38238631 37938618 37378645 37338692
               37488739 37878793