Storm Prediction Center Mesoscale Discussion 1969

   Mesoscale Discussion 1969
   NWS Storm Prediction Center Norman OK
   0806 PM CDT Sat Aug 16 2025

   Areas affected...portions of northeastern Iowa southwest Wisconsin
   and northern Illinois

   Concerning...Severe potential...Watch unlikely 

   Valid 170106Z - 170230Z

   Probability of Watch Issuance...20 percent

   SUMMARY...Storms forming along a trailing outflow boundary may
   remain capable of sporadic hail and occasional strong wind gusts for
   a few hours this evening.

   DISCUSSION...As of 01 UTC, regional radar imagery showed several
   clusters of storms had redeveloped along a trailing outflow boundary
   from prior convection across portions of northern IL, eastern IA and
   southwestern WI. Several of these storms have shown periods of
   higher intensity with reports of hail over the last hour. This
   threat should continue with occasional hail or damaging gusts as the
   air mass along and south of the outflow remains very unstable with
   4000-5000 j/kg of MUCAPE. Vertical shear, while not overly strong
   (25-35 kt 0-6km agl), is sufficient for a mixed convective mode of
   multicell clusters and transient supercell structures near the
   boundary.

   The tendency for developing storms to move eastward toward weaker
   buoyancy suggests intensification of individual cells should be
   relatively brief. Additionally, the strongest vertical shear remains
   displaced farther north which should keep overall organization
   limited. A WW is unlikely given the lack of a more focused/sustained
   severe risk, but occasional hail and a damaging gust are possible.

   ..Lyons/Smith.. 08/17/2025

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

   ATTN...WFO...LOT...MKX...DVN...ARX...

   LAT...LON   41308897 41728984 42259068 42849174 43259169 43279015
               42868903 42028796 41488801 41278823 41308897 

   MOST PROBABLE PEAK WIND GUST...55-70 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN