Mesoscale Discussion 1717
   NWS Storm Prediction Center Norman OK
   0517 PM CDT Sat Sep 26 2020

   Areas affected...Parts of east central Minnesota...northern
   Wisconsin and western Upper Michigan

   Concerning...Severe potential...Watch possible 

   Valid 262217Z - 270015Z

   Probability of Watch Issuance...40 percent

   SUMMARY...Increasing thunderstorm development appears likely in a
   corridor across northern Wisconsin and adjacent western Upper
   Michigan through 7-9 PM CDT.  This activity probably will pose a
   risk for severe hail, and perhaps increasing potential for strong
   wind gusts later this evening.

   DISCUSSION...A fairly significant mid-level short wave trough is
   just now beginning to dig into the northern Great Plains, but a
   number of lower-amplitude perturbations precede it within broadly
   cyclonic downstream flow into the upper Great Lakes region.  One
   appears to be aiding recent new thunderstorm development
   north/northeast of the Minneapolis MN area.  This activity appears
   focused and rooted within lower/mid tropospheric warm advection,
   near the nose of a plume of warm elevated-mixed layer air.  

   This may be occurring mostly north of the steeper mid-level lapse
   rates, where most unstable CAPE may not exceed 500 J/kg.  But
   mid-levels are relatively cool, and model forecast soundings
   indicate vertical shear within the convective layer supportive of
   supercells.  Large hail appears the primary initial severe threat,
   but there appears potential for upscale convective growth as
   activity increases in coverage and develops eastward across northern
   Wisconsin through 00-02Z.  If this occurs, the evolution of a small,
   organizing convective cluster is possible and could be accompanied
   by increasing potential for strong surface gusts.

   ..Kerr/Hart.. 09/26/2020

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

   ATTN...WFO...MQT...GRB...DLH...ARX...MPX...

   LAT...LON   45769298 46059168 46419040 46678844 45888746 45438834
               45148970 44819158 44899297 45769298