Mesoscale Discussion 1747
   NWS Storm Prediction Center Norman OK
   0706 PM CDT Tue Oct 20 2020

   Areas affected...Northeast WI/central Upper MI

   Concerning...Heavy snow 

   Valid 210006Z - 210400Z

   SUMMARY...Hourly snowfall rates approaching 1" will be possible
   through about 05z, with a diminishing threat for locally heavy snow
   thereafter.

   DISCUSSION...In advance of a midlevel shortwave trough crossing the
   upper MS Valley, a zone of strong low-midlevel warm advection is
   ongoing across central/northern WI.  Ascent is resulting in
   saturation and widespread precipitation formation from central WI
   northward, and the combination of wet bulk cooling/melting has
   resulted in surface temperatures near 32 F across northwest and
   north central WI.  The zone of ascent and modest low-level cooling
   will spread northeastward toward central Upper MI this evening in
   tandem with the heavier precipitation rates, where snow is the
   likely precipitation type.  The warm advection will tend to support
   a broad zone of precipitation formation given the stable midlevel
   lapse rates, with the heavier precipitation rates (and greater
   snowfall potential) expected along and 1-2 counties north of the
   surface 32 F line.  Though focused banding is not expected given
   only weak frontogenesis, local snowfall rates could approach 1"/hour
   before the snow diminishes from southwest-to-northeast across
   central Upper MI toward about 05z.

   ..Thompson.. 10/21/2020

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

   ATTN...WFO...MQT...GRB...ARX...

   LAT...LON   46828776 46458769 46108776 45738786 45258825 44768889
               44508965 44769004 45309004 45778939 46898802 46828776