Mesoscale Discussion 1331
   NWS Storm Prediction Center Norman OK
   0125 PM CDT Fri Jul 23 2021

   Areas affected...Northwest Minnesota

   Concerning...Severe potential...Watch possible 

   Valid 231825Z - 232030Z

   Probability of Watch Issuance...40 percent

   SUMMARY...Thunderstorms may develop sooner than forecast guidance
   has suggested, possibly within the next couple of hours. Large hail
   and damaging winds would be the main threats this afternoon/evening.
   Trends are being monitored for a possible severe thunderstorm watch.

   DISCUSSION...Temperatures in northwestern Minnesota have risen into
   the low 90s F. This has occurred quicker than forecast guidance has
   suggested. With dewpoints still holding in the low 70s F, MLCAPE is
   also increasing to above 1500 J/kg. Within this environment, a field
   of cumulus has developed along with a handful of deeper towers in
   the vicinity of Thief River Falls. With an upstream shortwave trough
   evident on water vapor imagery within western/central North Dakota,
   subtle mid-level cooling will occur in northern Minnesota this
   afternoon. These factors would suggest that convection initiation is
   becoming more probable, perhaps as early as within the next couple
   of hours. With all 12Z guidance forecasting initiation during the
   late afternoon, timing remains the greatest uncertainty. When storms
   develop, long, straight hodographs with 35-40 kts of effective shear
   will favor splitting supercells capable of damaging winds and large
   hail. A severe thunderstorm watch is possible this afternoon
   depending on convective trends over the next few hours.

   ..Wendt/Hart.. 07/23/2021

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

   ATTN...WFO...DLH...FGF...

   LAT...LON   47519741 48339689 48949640 49029567 48679464 48199411
               47449404 46989473 46969686 47209732 47519741