US Mesoscale Discussions

Storm Prediction Center Mesoscale Discussion 1404

   Mesoscale Discussion 1404
   NWS Storm Prediction Center Norman OK
   0409 AM CDT Tue Jun 25 2024

   Areas affected...East-Central/Southern WI...Far Northern
   IL...Western Lower MI

   Concerning...Severe Thunderstorm Watch 455...

   Valid 250909Z - 251045Z

   The severe weather threat for Severe Thunderstorm Watch 455

   SUMMARY...Threat for severe gusts continues across southeast WI,
   with large hail more likely across far western Lower MI. Additional
   development is occurring across southwest WI and convective trends
   are being monitored for possible watch across southern WI and
   northern IL.

   DISCUSSION...Ongoing MCS has accelerated notably over the past hour
   or so, with storm motion now closer to 55 kt. The MCS has trended
   towards a more southerly motion as well, favoring now north-south
   oriented instability gradient. This more southerly motion may limit
   the chance that this MCS fully crosses Lake Michigan, with the
   strongest portion of the MCS potentially tracking closer to the
   southwestern shore of the lake. Strong gusts have started reaching
   the surface, with gusts of 55, 53 and 50 kt recently observed at
   SBM, GRB, and MTW, respectively. Potential for strong gusts is
   expected to persist within the line for at least the next few hours.

   Farther southwest, new thunderstorm development has occurred in the
   IA/WI/IL border intersection vicinity, within the core of the
   southwesterly low-level jet extending across the region. There
   appears to be some potential for additional development in southern
   WI, which would fill in the gap between these storms and the ongoing
   MCS. This scenario is uncertain, but could lead to am additional
   severe threat across southern WI and northern IL. As a result,
   convective trends are being monitored closely. 

   Thunderstorms continue to intensify within the warm-air advection
   wing that is now over far western Lower MI. Primary threat with
   these storms is large hail, but a strong gust or two is possible as

   ..Mosier/Edwards.. 06/25/2024

   ...Please see for graphic product...


   LAT...LON   42919078 44978796 44568574 43048531 42458690 41978959

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