Mesoscale Discussion 1184
   NWS Storm Prediction Center Norman OK
   1136 AM CDT Sat Jul 11 2020

   Areas affected...Parts of central/northern Iowa and adjacent
   southern Minnesota

   Concerning...Severe potential...Watch possible 

   Valid 111636Z - 111830Z

   Probability of Watch Issuance...60 percent

   SUMMARY...The initiation of intensifying storms appears possible by
   1-3 PM CDT, including the the evolution of discrete supercells
   posing a risk for large hail and severe wind gusts.

   DISCUSSION...A zone of large-scale ascent (inferred from water vapor
   imagery) south/southeast of the vigorous digging short wave trough,
   still over the eastern Dakotas/western Minnesota, appears in the
   process of overspreading a corridor of moderate to strong
   boundary-layer destabilization.  This is focused along an outflow
   boundary trailing the evolving cluster of storms approaching the
   Quad Cities area, and beneath the lower/mid tropospheric thermal
   gradient delineating the edge of more strongly capping elevated
   mixed-layer air.

   Attempts at deepening convective development appear underway along
   the outflow boundary to the west of the Cedar Rapids through
   Waterloo, perhaps as well as within a cluster southeast of Spencer. 
   As the mid-level forcing for ascent continues to overspread this
   corridor through 18-20Z, there appears potential for rapid further
   convective development and intensification, in the presence of CAPE
   increasing in excess of 2000 J/kg.  Aided by moderate to strong
   deep-layer shear beneath 30-40 kt northwesterly 500 mb flow, this
   may include the evolution of isolated supercells initially, posing a
   risk for large hail and severe wind gusts.

   ..Kerr/Guyer.. 07/11/2020

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

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

   LAT...LON   43589442 42259184 41769215 42309411 42749525 43549601
               43589442