Mesoscale Discussion 1470
   NWS Storm Prediction Center Norman OK
   1236 AM CDT Wed Aug 12 2020

   Areas affected...North-Central/Northeast South Dakota

   Concerning...Severe potential...Watch possible 

   Valid 120536Z - 120700Z

   Probability of Watch Issuance...40 percent

   SUMMARY...Ongoing mesoscale convective system is expected to persist
   eastward into more of north-central and northeast SD. Potential for
   damaging wind gusts exists with this system and trends will be
   monitored closely for downstream watch issuance.

   DISCUSSION...A strong to occasionally severe MCS continues to move
   east-southeastward across north-central SD at 35 kt. At this speed,
   the system will reach the edge of Severe Thunderstorm Watch 432
   before 06Z. Steep mid-level lapse rates downstream support moderate
   to strong buoyancy, with recent mesoanalysis estimating MLCAPE
   around 2500 J/kg. Vertical shear is modest (i.e. effective bulk
   shear around 35 kt), but still strong enough to support persistence
   of the ongoing cluster. Additionally, recent radar trends have shown
   a tendency toward slightly faster easterly motion over the past half
   hour or so. KABR velocity data also shows strong inbounds around
   14-15 kft, indicating the presence of a rear-inflow jet. All of
   these factors suggest the system is organized enough to persist
   downstream for at least the next several hours. Low-level stability
   may prevent strong gusts from reaching the surface at max strength.
   However, a strengthening low-level flow ahead of the line could
   moisten low-levels enough to reduce the low-level stability,
   increasing the potential for damaging wind gusts. Trends will be
   monitored closely for potential downstream watch issuance.

   ..Mosier/Hart.. 08/12/2020

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

   ATTN...WFO...FSD...ABR...UNR...

   LAT...LON   45740097 45870007 45729818 44459824 44469946 44930117
               45740097