Storm Prediction Center Mesoscale Discussion 1920

   Mesoscale Discussion 1920
   NWS Storm Prediction Center Norman OK
   0153 PM CDT Fri Aug 16 2024

   Areas affected...central and southern Wisconsin into parts of
   eastern Iowa and northern Illinois

   Concerning...Severe potential...Watch unlikely 

   Valid 161853Z - 162130Z

   Probability of Watch Issuance...20 percent

   SUMMARY...Thunderstorm activity likely will continue to increase in
   coverage while also slowly intensifying across central into
   southwestern Wisconsin, and perhaps adjacent portions of eastern
   Iowa and northern Illinois, through 3-5 PM CDT.  Some small to
   marginally severe hail is possible, before activity gradually
   organizes and poses a risk for strong to severe gusts while
   approaching southern Lake Michigan into early evening.

   DISCUSSION...Convection has recently been intensifying over central
   Wisconsin, near Wisconsin Rapids.  This is beneath the modest
   mid-level cold core of a broad mid/upper low slowly shifting into
   the upper Great Lakes region, and in advance of an associated
   intrusion of cooler/drier air which has overspread much of Minnesota
   and northwestern Wisconsin.  Wind fields and shear near the ongoing
   convection are rather weak, but low-level lapse rates have become
   relatively steep with daytime heating, and easterly low-level inflow
   into convection appears characterized by CAPE up to 2000 J/kg.  

   To the west and southwest of this convection, a digging mid-level
   cyclonic vorticity center and associated speed maximum may
   contribute to forcing for gradually increasing new thunderstorm
   development across southwestern into south central Wisconsin and
   adjacent portions of Iowa/northern Illinois through 20-22Z.  As this
   occurs, in closer proximity to the jet streak, strengthening of flow
   in the 700-500 mb layer (to 30-40 kt) may be sufficient to support
   organizing convection.  This may gradually be accompanied by a
   strengthening surface cold pool with by strong to locally severe
   gusts while advancing toward southern Lake Michigan into this
   evening.

   ..Kerr/Thompson.. 08/16/2024

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

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

   LAT...LON   42479086 43409025 44158951 43638787 42298835 42018952
               42049073 42479086