Storm Prediction Center Mesoscale Discussion 467

   Mesoscale Discussion 0467
   NWS Storm Prediction Center Norman OK
   0722 AM CDT Fri Apr 18 2025

   Areas affected...Southern Wisconsin...Lake Michigan

   Concerning...Severe Thunderstorm Watch 142...

   Valid 181222Z - 181415Z

   The severe weather threat for Severe Thunderstorm Watch 142
   continues.

   SUMMARY...A severe threat will likely continue over the next couple
   of hours from parts of southern Wisconsin eastward over Lake
   Michigan. Significant wind gusts and large hail will be possible
   with the strongest of cells.

   DISCUSSION...The latest high-resolution radar imagery from KMKX
   shows a cluster of strong to severe storms over southern Wisconsin,
   with a severe short line segment located about 40 statute miles to
   the west of Milwaukee, Wisconsin. The storms are located along an
   east-to-west gradient of instability, where the RAP is estimating
   MUCAPE around 1000 J/kg. RAP forecast soundings to the west of
   Milwaukee still have a temperature inversion from the surface to 850
   mb, with strong effective shear above the inversion. This will
   continue to support elevated supercell development. In addition,
   forecast soundings have steep lapse rates in the 700 to 500 mb
   layer, which will aid a threat for large hail with supercells.
   Hailstones greater than 2 inches in diameter will be possible in the
   more intense cores. The stronger and faster moving line segments
   could also produce severe gusts, with 70+ mph gusts possible. The
   severe threat is expected to become more isolated later this
   morning. To the east of the current watch, watch issuance probably
   won't be needed. Trends will be monitored.

   ..Broyles/Gleason.. 04/18/2025

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

   ATTN...WFO...GRR...LOT...MKX...ARX...

   LAT...LON   43328623 42978610 42648625 42508658 42488814 42558932
               42619011 42769037 43059037 43369020 43578977 43598821
               43528671 43328623 

   MOST PROBABLE PEAK WIND GUST...65-80 MPH
   MOST PROBABLE PEAK HAIL SIZE...2.00-3.50 IN