Mesoscale Discussion 1678
   NWS Storm Prediction Center Norman OK
   0232 AM CDT Sun Sep 06 2020

   Areas affected...Southern MN...Northern/Northeast/Eastern IA...Far
   Southwest WI...Northwest IL

   Concerning...Severe Thunderstorm Watch 486...

   Valid 060732Z - 060900Z

   The severe weather threat for Severe Thunderstorm Watch 486
   continues.

   SUMMARY...Threat for severe hail and damaging wind gusts will
   continue for the next few hours. Given that Severe Thunderstorm
   Watch #486 is set to expire at 08Z, a watch extension and/or new
   watch will be needed to address the continuing severe threat.

   DISCUSSION...Recent surface observations reveal the position of the
   warm front has been modified slightly by storm outflow. Currently
   the warm front lies from FSD (in far southwest SD)
   east-southeastward to AXA (in north-central IA) and then more
   southeastward across IA to near MUT on the southern IL/IA border.
   Intense updrafts persist within several of the thunderstorms north
   of this front across south-central MN/north-central IA into
   northeast/east-central IA. 

   Recent radar imagery has shown a trend toward more storm clustering
   and forward propagation, potential signalling a transition to more
   cold pool dominant storm structures. Even with the elevated nature
   of the ongoing storms, cold pool amalgamation is still possible,
   with the resulting clusters then progressing quickly southeastward.

   A strong low-level jet will continue to support warm-air advection
   across the frontal zone, helping to provide warm, moist inflow to
   the ongoing storms. Expectation is for the threat for large hail and
   damaging wind gusts to persist for at least the next few hours,
   particularly from south-central MN/north-central IA downstream into
   southwest WI and northwest IL. Severe Thunderstorm    Watch #486 is
   set to expire at 08Z and a watch extension and/or new watch will
   likely be needed to address the continuing severe threat.

   ..Mosier/Guyer.. 09/06/2020

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

   ATTN...WFO...LOT...ILX...MKX...DVN...ARX...MPX...DMX...FSD...

   LAT...LON   44479532 44639379 43609117 41848918 40589060 42059401
               43199544 44479532