Mesoscale Discussion 1540
   NWS Storm Prediction Center Norman OK
   0740 AM CDT Sat Jul 20 2019

   Areas affected...Portions eastern SD into southern MN and northern
   IA

   Concerning...Severe Thunderstorm Watch 528...

   Valid 201240Z - 201415Z

   The severe weather threat for Severe Thunderstorm Watch 528
   continues.

   SUMMARY...Damaging, severe wind gusts will remain possible with
   storms moving from eastern South Dakota into southern Minnesota and
   northern IA. Downstream watch issuance is possible (60% chance).

   DISCUSSION...A long-lived convective line has produced multiple
   severe and damaging wind gusts across central/eastern SD this
   morning. Strong inbound velocities have been observed with this line
   from the KFSD radar. A surface front lies generally southwest to
   northeast from southeastern SD into southern MN and northern IA. As
   this line begins to encounter greater surface-based instability, its
   potential to produce damaging winds may increase. Northerly
   low-level winds quickly veer to southwesterly while also
   strengthening through mid levels. Resultant effective bulk shear
   values of 40-55 kt will easily support continued organization within
   the line this morning. A downstream Severe Thunderstorm Watch is
   possible across parts of southern MN into northern IA to address
   mainly the severe/damaging wind threat. 

   Farther east, a band of elevated thunderstorms associated with warm
   air advection centered in the 850-700 mb layer has developed over
   southern MN the past couple of hours. Modestly steepened mid-level
   lapse rates were observed on the 12Z sounding from MPX, with around
   2250 J/kg of MUCAPE present. Even greater instability (MUCAPE up to
   4000 J/kg) is being estimated by mesoanalysis feeding into the
   southern flank of the ongoing band of storms. Strong effective shear
   of 45-55+ kt in addition to the plentiful instability has fostered
   robust updrafts embedded within the overall band. Marginally severe
   hail will remain possible this morning with the strongest cores,
   although predominant cluster storm mode may tend to limit a greater
   hail threat.

   ..Gleason/Grams.. 07/20/2019

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

   ATTN...WFO...ARX...MPX...DMX...FSD...ABR...

   LAT...LON   43489749 43699765 44019743 44419711 44999678 44979602
               44799504 44549416 44719286 44419223 44039178 43289167
               42919186 42919294 42929497 43029643 43149701 43489749