Mesoscale Discussion 1433
   NWS Storm Prediction Center Norman OK
   1230 PM CDT Sun Aug 09 2020

   Areas affected...Portions of far eastern MN into northwestern and
   north-central WI

   Concerning...Severe potential...Watch possible 

   Valid 091730Z - 092000Z

   Probability of Watch Issuance...60 percent

   SUMMARY...The severe threat should gradually increase this
   afternoon, with a few tornadoes, damaging winds, and large hail all
   possible. Watch issuance may be needed in the next couple of hours
   to address this threat.

   DISCUSSION...Recent visible satellite and radar imagery show a
   well-defined MCV circulation over central MN. This mid-level
   circulation appears to be somewhat displaced to the northwest of the
   related surface meso-low near the Twin Cities, and this displacement
   may affect the low-level wind fields and limit the severe threat in
   the near term. Still, some cloud breaks to the east of the MCV
   across far eastern MN into northwestern/north-central WI are
   allowing surface temperatures to slowly warm into the upper 70s and
   80s. Coupled with surface dewpoints in the upper 60s to lower 70s,
   this modest diurnal heating should support the development of
   1500-2000 J/kg of MLCAPE by mid afternoon, with locally stronger
   instability possible.

   Some uncertainty remains regarding the placement of greater storm
   coverage, as the mid-level vorticity maximum associated with the MCV
   should move quickly northeastward along the northern fringes of the
   stronger instability this afternoon. Earlier VWPs from KMPX showed
   considerable veering/strengthening of the low and mid-level wind
   field ahead of the MCV. Forecast soundings from the RAP across
   northwestern WI and vicinity suggest a sufficiently strong wind
   field through mid levels to support organized severe thunderstorms,
   including the potential for supercells initially.

   With effective SRH of 150-200 m2/s2 forecast across this area, a few
   tornadoes appear possible if the storm mode can remain at least
   somewhat discrete. Isolated large hail may also occur with this
   initial activity given the favorable forecast instability and shear.
   Convection should tend to form into one or more small clusters later
   this afternoon across northern WI, and damaging winds may eventually
   become the primary threat. Trends will continue to be closely
   monitored for signs of increasing storm coverage and intensity
   across far eastern MN into northwestern WI, and watch issuance may
   be needed in the next couple of hours.

   ..Gleason/Grams.. 08/09/2020

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

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

   LAT...LON   44469205 44709297 45529318 46159275 46639211 46669124
               46419017 46168966 45618933 44848955 44669017 44519095
               44469205