Mesoscale Discussion 1604 NWS Storm Prediction Center Norman OK 0920 PM CDT Thu Aug 27 2020 Areas affected...far southeast Montana into western South Dakota. Concerning...Severe Thunderstorm Watch 460... Valid 280220Z - 280345Z The severe weather threat for Severe Thunderstorm Watch 460 continues. SUMMARY...Severe thunderstorms ongoing across portions of WW460 are expected to continue with a threat for damaging winds and large hail this evening. Upscale growth into an MCS appears probable with an increasing risk for damaging winds downstream where a new watch is likely later this evening. DISCUSSION...Several clusters of severe storms are currently ongoing across WW460 this evening. Recent reports of severe hail and wind gusts in excess of 70 mph signal continued organization of storms across South Dakota. The 00z UNR sounding shows an environment supportive of severe thunderstorms (including supercells) with 2000 J/kg of MLCAPE and 55 kts of effective shear. 8.5-9 C/km mid-level lapse rates and supercell wind profiles suggest the threat for large to very large hail will likely continue for a few more hours, before upscale growth associated with the low-level jet and storm mergers shifts the threat toward damaging winds. A downstream watch is likely by 04z as cluster of storms is expected to organize into an MCS across southern South Dakota later this evening. Across southern North Dakota, some hi-res guidance has shown an increase in convective coverage between 03-04z. Despite the increasing inhibition, 1000-1500 J/kg of MUCAPE would support some severe potential, primarily in the form of damaging winds and occasional severe hail, with any storm clusters that are able to organize. ..Lyons/Guyer.. 08/28/2020 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...FSD...ABR...BIS...UNR...BYZ... LAT...LON 46780338 46740196 46650085 45379886 44299848 43069917 43060285 43760430 44780452 45620430 46780338