Mesoscale Discussion 1246
   NWS Storm Prediction Center Norman OK
   0955 AM CDT Fri Jul 17 2020

   Areas affected...Southeast South Dakota into northwest Iowa and
   southwest Minnesota

   Concerning...Severe potential...Watch unlikely 

   Valid 171455Z - 171630Z

   Probability of Watch Issuance...5 percent

   SUMMARY...Isolated strong to severe thunderstorms may persist for
   the next couple of hours and pose a threat for severe hail. A watch
   is not likely due to uncertainty in the duration of the threat.

   DISCUSSION...Regional radar over the past hour has shown a cluster
   of discrete to semi-discrete thunderstorms across southeast SD. Some
   of these storms have exhibited transient supercellular
   characteristics and briefly produced severe hail. This elevated
   convection is most likely being forced within a zone of 700 mb warm
   advection ahead of a mid-level trough to the west. This zone of
   ascent has been gradually shifting to the east/northeast, but slow
   storm motions at around 20 knots should allow these storms to remain
   in this region of ascent. Although recent radar trends have shown a
   gradual weakening trend, a favorable environment, characterized by
   2000-3000 J/kg MUCAPE, 7-8 C/km mid-level lapse rates, and
   sufficient 25-35 knots of effective bulk shear, remains supportive
   of organized convection. One or two additional strong to severe
   storms are possible over the next couple of hours.

   However, there remains considerable uncertainty regarding the
   duration of this threat. Morning guidance has largely struggled
   resolving this convection, and recent radar trends suggest the
   forcing for ascent may not be sufficient to support long-duration
   convection. But given no foreseeable degradation to the environment
   in the next 2-3 hours and continued weak forcing for ascent, the
   development of new convection appears possible through the mid to
   late morning hours.

   ..Moore/Hart.. 07/17/2020

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

   ATTN...WFO...FSD...OAX...

   LAT...LON   42849793 43749798 44389711 44409610 43849539 43089492
               42759548 42629688 42849793