Mesoscale Discussion 1367
   NWS Storm Prediction Center Norman OK
   0254 PM CDT Fri Jul 31 2020

   Areas affected...southwest North Dakota and western South Dakota

   Concerning...Severe potential...Watch unlikely 

   Valid 311954Z - 312200Z

   Probability of Watch Issuance...20 percent

   SUMMARY...Thunderstorms will continue to develop/strengthen this
   afternoon. Conditions will be favorable for isolated damaging
   thunderstorm winds and some hail. Conditions will continue to be
   monitored for potential need for a Severe Thunderstorm Watch, but
   one is not currently anticipated.

   DISCUSSION...Thunderstorms are developing/strengthening on the
   eastern edge of a mesoscale convective vortex (MCV) across eastern
   Montana. These thunderstorms should continue to develop and increase
   in both strength and coverage this afternoon as the MCV interacts
   with a surface front moving south across North Dakota. The overall
   movement of the MCV and surface boundary, coupled with northerly
   mid-level flow, favor a south to southeast storm motion.

   Instability appears to be maximized to the east of the ongoing
   thunderstorms/MCV where surface temperatures have warmed into the
   80s F and dewpoints are currently in the 60s F, leading to
   most-unstable CAPE on the order of 2000-3000 J/kg with little-to-no
   surface inhibition left. However, deep-layer shear is rather weak,
   except locally/sub-synoptically augmented to the east of the MCV,
   which should limit the overall organizational potential of any
   thunderstorm updraft/downdraft pairs. 

   Given the degree of instability, a surface boundary, and an MCV all
   interacting with one another, strong-to-severe multi-cell
   thunderstorms are possible across the region this afternoon.
   Mid-level lapse rates around 7 C/kg may support an isolated
   hail/large-hail risk with the strongest updrafts, however, potential
   strong thunderstorm winds associated with developing/congealing cold
   pools will be the more likely threat. 

   The lack of stronger shear and the pulse-based nature of any severe
   thunderstorm should preclude the need for a severe thunderstorm
   watch, but conditions will continue to be monitored.

   ..Marsh/Bunting.. 07/31/2020

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

   ATTN...WFO...ABR...BIS...UNR...

   LAT...LON   45580330 47200301 46650025 44719978 44490149 45580330