Mesoscale Discussion 1006
   NWS Storm Prediction Center Norman OK
   1238 PM CDT Fri Jun 26 2020

   Areas affected...Northeastern Iowa...southeastern
   Minnesota...southern Wisconsin...northern Illinois

   Concerning...Severe potential...Watch likely 

   Valid 261738Z - 261945Z

   Probability of Watch Issuance...80 percent

   SUMMARY...Storm coverage and intensity should slowly increase this
   afternoon as ares of cloud breaks allow for surface-based
   destabilization. Large hail and damaging wind gusts will be the
   primary threats. A tornado or two will be possible, primarily in
   southern WI/northern IL, as the airmass tries to destabilize near an
   outflow boundary. A WW will likely be needed by 18-19Z.

   DISCUSSION...A storm has recently initiated along the MN/IA border
   roughly where an MCV is interacting with a differential heating
   zone. Recent KDMX and KDVN VAD data shows around 50 kts of flow at 6
   km associated with the MCV. Heating of a moist airmass--dewpoints
   generally in the low 70s--may eventually support MLCAPE in the
   neighborhood of 2000 J/kg. Storm coverage is expected to increase
   this afternoon both near the MCV and along the differential heating
   zone/outflow boundary into northern IL. A 17Z sounding at GRB
   sampled 7 C/km mid-level lapse rates which, given modest effective
   shear, should support organized convection capable of large hail and
   damaging wind gusts. The most intense storms are likely near and
   south of the outflow this afternoon. Storms farther north are likely
   to be less severe given the amount of cloud cover limiting
   destabilization. Some modest low-level hodograph size is expected
   near the outflow boundary. Should the airmass recover more this
   afternoon, the threat for a tornado or two would exist primarily in
   southern WI and northern IL. Initial convection will tend to grow
   upscale with time along with further linear development along the
   advancing cold front to the west. A WW will likely be needed by
   18-19Z.

   ..Wendt/Thompson.. 06/26/2020

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

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

   LAT...LON   41489148 41889222 42899301 43649299 44029200 44048951
               43818820 43248774 42898775 41868791 41568811 41108987
               41489148