Mesoscale Discussion 1437
   NWS Storm Prediction Center Norman OK
   0712 PM CDT Sat Aug 07 2021

   Areas affected...Portions of the Dakotas

   Concerning...Severe potential...Watch unlikely 

   Valid 080012Z - 080145Z

   Probability of Watch Issuance...20 percent

   SUMMARY...Isolated severe storms near an area of low pressure across
   the Dakotas may pose a risk for damaging winds and isolated hail
   this evening. A non-supercell tornado may also be possible in
   vicinity of the surface low. Storm coverage is expected to remain
   low suggesting a watch is unlikely.

   DISCUSSION...Evening water vapor imagery showed a well defined
   shortwave trough moving out of the Rockies and into the central
   Plains. Ahead of this wave, an area of low pressure at the surface
   was observed near the north Dakota south Dakota Border. Lift from a
   cold front extending south from the low has resulted in isolated
   storm development along an arcing line from south-central North
   Dakota to near Aberdeen, South Dakota. Despite prominent smoke and
   haze, daytime heating and dewpoints in the upper 60s F have resulted
   in moderate instability (2000-3000 J/kg of MLCAPE). Winds aloft
   however are weak, with the Aberdeen VAD indicating effective shear
   remains below 30 kts. Severe potential appears modest, but a few
   stronger multicell storms may become organized early this evening.
   Steep mid-level lapse rates and large buoyancy will support the
   potential for severe hail and damaging outflow winds with the
   strongest storms. Enhanced stretching from 0-3km CAPE in excess of
   100 J/kg east of the low center and locally greater vertical
   vorticity beneath the vortmax may also support a non-supercell
   tornado this evening. Uncertainty on storm organization remains
   high, suggesting that a weather watch is unlikely.

   ..Lyons/Hart.. 08/08/2021

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

   ATTN...WFO...FGF...ABR...BIS...

   LAT...LON   46839944 46909911 46889850 46729801 46469758 45999710
               45489718 45139766 45069844 45289872 45599876 45989900
               46189955 46639977 46839944