Mesoscale Discussion 1841
   NWS Storm Prediction Center Norman OK
   1254 PM CST Sat Dec 12 2020

   Areas affected...northeast Michigan

   Concerning...Heavy snow 

   Valid 121854Z - 122300Z

   SUMMARY...Snow bands continue to develop over northeast Michigan
   where the potential heavy snow will likely continue well into the
   late afternoon and early evenings hours. Snowfall rates between 1-2
   inches remain likely with snow rates exceeding two inches per hour
   possible for some locations.

   DISCUSSION...MRMS imagery over the past 1-2 hours has shown somewhat
   persistent snow banding across the northeast quadrant of MI.
   Subsequently, surface observations have shown prolonged periods of
   visibility reductions between one-half to one-quarter mile due to
   heavy snow with regional webcams showing widespread snow
   accumulation and reduced visibility at times. Recent snowfall
   reports between 6-7 inches across this region further support radar
   and surface observation trends. 

   Recent RAP mesoanalysis suggests that a tight 850 mb baroclinic zone
   remains in place over northern MI with strong mid-level warm
   advection continuing between the 850-700 mb layers ahead of the main
   upper-level low. Water vapor imagery shows this upper-level low
   beginning to approach southern MI, suggesting that the stronger
   forcing for ascent will gradually begin diminishing from west to
   east across west/northwest MI. However, the combined synoptic and
   mesoscale forcing mechanisms supportive of organized snow banding
   will likely linger over northeast MI into the late afternoon and
   evening hours. As such, the potential for persistent moderate to
   heavy snowfall rates between 1-2 inches per hour continues. A few
   locations may observe periodic snowfall rates exceeding two inches
   per hour - especially locations along the western shore of Lake
   Huron where some lake-effect enhancement is possible due to the
   somewhat warm (40-44 F) lake water temperatures and onshore flow.
   Most guidance continues to suggest that the heavy snow potential
   will begin to gradually abate from west to east between 22-00 UTC.

   ..Moore.. 12/12/2020

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

   ATTN...WFO...APX...

   LAT...LON   45368517 45838460 45788388 45518327 45078303 44748307
               44468328 44258384 44228451 44328492 44578519 45048520
               45368517