Storm Prediction Center Mesoscale Discussion 2086

   Mesoscale Discussion 2086
   NWS Storm Prediction Center Norman OK
   0126 PM CDT Thu Sep 19 2024

   Areas affected...parts of east central and southeastern
   Minnesota...adjacent northern Iowa and west central Wisconsin

   Concerning...Severe potential...Watch likely 

   Valid 191826Z - 192030Z

   Probability of Watch Issuance...80 percent

   SUMMARY...Strong thunderstorm development appears increasingly
   likely through 3-5 PM CDT, near/northwest of the Greater Minneapolis
   area into areas southwest of Mankato.  This probably will include
   the evolution of at least widely scattered supercells posing a risk
   for severe hail, with largest hailstones perhaps exceeding 2 inches
   in diameter.

   DISCUSSION...To the southeast of an occluded lower/mid-tropospheric
   cyclone, now beginning to redevelop eastward across southern
   Manitoba, moderately strong destabilization is ongoing.  This is
   generally focused ahead of a residual wind shift, within a plume of
   higher low-level moisture content which is being maintained beneath
   a tongue of cool mid-level air.  CAPE (up to 1500-2000 J/kg) appears
   maximized within a rather narrow corridor beneath steep mid-level
   lapse rates which roughly coincide with 500 mb temperatures around
   -13 to -14 C.  This is forecast to continue slowly shifting across
   the central through eastern Minnesota vicinity through mid to late
   afternoon.

   A relative warm layer around or just below the 700 mb level is
   tending to suppress boundary-layer based thunderstorm initiation
   along the potential instability axis.  However, model output is
   suggestive that forcing for ascent in the left exit region of an
   approaching jet streak, near the southern periphery of the cyclonic
   mid/upper flow, will contribute to thunderstorm development across
   southern Minnesota and adjacent northern Iowa by 20-22Z.

   In the presence of at least strong deep-layer shear, it appears that
   this will probably include widely scattered to scattered supercells,
   initially generally west of the Minneapolis through Mankato
   vicinities.  These probably will pose a risk for severe hail, with
   largest stones perhaps exceeding 2 inches in diameter.

   ..Kerr/Gleason.. 09/19/2024

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

   ATTN...WFO...DLH...ARX...MPX...DMX...FSD...

   LAT...LON   44949418 45939279 45289127 43599265 43039368 43259525
               44949418