Mesoscale Discussion 1691
   NWS Storm Prediction Center Norman OK
   0356 PM CDT Sat Aug 10 2019

   Areas affected...Southern MN...Western/central IA

   Concerning...Severe potential...Watch unlikely 

   Valid 102056Z - 102300Z

   Probability of Watch Issuance...20 percent

   SUMMARY...At least isolated thunderstorm development is possible
   this afternoon. The strongest cells will be capable of producing
   locally damaging wind and perhaps a tornado or two. Due to
   uncertainty regarding the coverage of the threat, watch issuance is
   currently considered unlikely.

   DISCUSSION...The latest surface analysis depicts a weak surface low
   across southwest MN, with a surface boundary extending eastward
   across southern MN and then southeastward into northeastern IA. A
   zone of weakly confluent flow, likely related to differential
   heating, is also noted extending south of the low into western IA.
   Widespread cloudiness has limited heating across the region, but
   rich low-level moisture is supporting MLCAPE ranging from 500 J/kg
   across the eastern portion of the MCD area to around 2000 J/kg
   across the western portion. Thunderstorm development will be
   possible later this afternoon near these surface features, with the
   greatest threat likely near the confluence zone across
   northwest/north-central IA where somewhat greater destabilization is
   occurring. 

   Moderate mid/upper-level flow is resulting in effective shear of
   40-50 kt across the region, more than sufficient for organized storm
   structures (including supercells) should convection develop. Warm
   midlevel temperatures and generally weak midlevel lapse rates are
   likely to mitigate the severe threat (especially hail) to some
   extent, but eventual development of one or two supercells is
   possible. Locally damaging wind would be the primary threat, but a
   tornado or two would also be possible, given favorable
   boundary-layer moisture and marginally supportive low-level shear
   profiles. 

   Watch issuance is currently considered unlikely due to uncertainty
   regarding the number of storms that can develop across this region.
   However, this will be re-evaluated if multiple organized cells
   appear imminent.

   ..Dean/Grams.. 08/10/2019

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

   ATTN...WFO...MPX...DMX...FSD...

   LAT...LON   41379495 42219508 43389523 44169532 44389491 44339399
               44029329 42499301 41769330 41539377 41379495