Mesoscale Discussion 1129
   NWS Storm Prediction Center Norman OK
   0123 PM CDT Tue Jul 07 2020

   Areas affected...Parts of northeast Iowa into far southeast
   Minnesota and southwest Wisconsin

   Concerning...Severe potential...Watch unlikely 

   Valid 071823Z - 072030Z

   Probability of Watch Issuance...20 percent

   SUMMARY...Damaging gusts and perhaps a severe hailstone or two are
   possible with the stronger updrafts. The isolated nature of the
   severe threat precludes a WW issuance.

   DISCUSSION...Ample insolation south of a baroclinic zone has
   resulted in surface temperatures approaching 90F amidst near 70F
   dewpoints based on latest METAR observations. Diurnal
   heating/moistening of the boundary layer has promoted the steepening
   of low-level lapse rates (with MLCAPE reaching 1500-2000 J/kg) and
   convective initiation along the MN/WI border. With the approach of
   an MCV across central/northern IA and continued diurnal heating, a
   gradual increase in convective coverage and intensity is expected
   through the afternoon hours, as also depicted in the latest
   high-resolution model guidance. 

   Weak tropospheric flow will result in poor deep-layer and low-level
   speed/directional shear profiles, with mainly short-lived
   pulse-cellular or perhaps transient multicellular structures being
   the most likely storm mode. Given steepening low-level lapse rates,
   effective downward momentum transport/evaporative cooling may result
   in a few damaging gusts with the more intense storms. A longer
   lasting, more organized cell/cluster may support one or two
   instances of severe hail, as relatively poor (5.5-6 C/km) mid-level
   lapse rates will temper the hail threat somewhat. Nonetheless, the
   severe threat is expected to remain sparse and brief, with a WW
   issuance not anticipated.

   ..Squitieri/Hart.. 07/07/2020

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

   ATTN...WFO...GRB...MKX...DVN...ARX...MPX...DMX...

   LAT...LON   43189349 43859281 44499158 44619059 44618995 44438962
               43678864 42798880 42408981 42159089 42359253 43189349