Mesoscale Discussion 1306
   NWS Storm Prediction Center Norman OK
   0613 PM CDT Tue Jul 21 2020

   Areas affected...western Wisconsin and far eastern Minnesota

   Concerning...Severe potential...Watch possible 

   Valid 212313Z - 220015Z

   Probability of Watch Issuance...40 percent

   SUMMARY...Isolated cells have acquired rotation across northwestern
   and southwestern WI over the past hour or so.  A WW issuance is
   possible and convective trends are being monitored.

   DISCUSSION...Surface heating and convergence along a surface trough
   located roughly near the Mississippi River has allowed for isolated
   to scattered thunderstorm development to occur across northwestern
   and southwestern Wisconsin.  A few rotational signatures have been
   observed via radar over the past half hour, and this isn't
   particularly surprising given backed low-level winds near and east
   of the surface trough.  Low LCLs and 100-150 m2/s2 0-1km SRH will
   support a brief/isolated tornado threat with these cells despite
   modest mid-level lapse rates for strong updrafts.  Furthermore, the
   temporal extent of the threat should be limited to the next 1-2
   hours or so as nocturnal surface cooling should decrease overall
   instability and any attendant severe threat.  Trends are being
   monitored for a possible WW issuance.

   ..Cook/Grams.. 07/21/2020

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

   ATTN...WFO...GRB...MKX...DLH...ARX...MPX...

   LAT...LON   46099169 45999223 45629256 44989259 44229220 43589159
               43259069 43319003 43788958 44518983 45399031 45899108
               46099169