Mesoscale Discussion 1157
   NWS Storm Prediction Center Norman OK
   0544 PM CDT Mon Jul 05 2021

   Areas affected...Far southeast South Dakota into northwest Iowa

   Concerning...Severe potential...Watch unlikely 

   Valid 052244Z - 060045Z

   Probability of Watch Issuance...5 percent

   SUMMARY...Thunderstorms may develop along a stationary boundary
   across northwest to north-central Iowa prior to sunset, though the
   potential for additional storms is uncertain. However, storms that
   do form could pose a brief severe hail risk.

   DISCUSSION...Recent satellite imagery continues to show a generally
   shallow cumulus field along a stationary boundary draped across
   northern IA. Despite the meager appearance of the cumulus field, new
   convection has been intensifying at the intersection of the boundary
   and convective outflow from an upstream cluster of storms across
   southeast SD. Although lift is locally augmented at this
   intersection, objective analysis trends over the past hour suggest 
   convergence may be gradually increasing along the stationary
   boundary across northwest IA, and RAP forecast soundings hint that
   low-level parcels are near their convective temperatures. This
   suggests that an isolated thunderstorm or two could develop either
   1) along the stationary boundary (likely prior to sunset and the
   onset of boundary-layer stabilization) or 2) along the convective
   outflow as it gradually pushes east through the evening hours.
   Confidence in either solution is somewhat low, and storm chances
   decrease with eastward extent due to weaker convergence/implied
   ascent. Given moderate instability in place (upwards of 3000 J/kg
   MLCAPE), any storms that do form may initially be capable of
   producing severe hail, though the lack of sufficient deep-layer
   shear will limit the duration of this threat. Given the lack of
   confidence in storm coverage and low potential for robust storm
   organization, a watch is not expected.

   ..Moore/Hart.. 07/05/2021

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

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

   LAT...LON   43519755 43799713 43489638 43379539 43369469 43279407
               43099342 42579342 42389401 42569502 42639637 42699702
               42889763 43099788 43519755