Mesoscale Discussion 0043
   NWS Storm Prediction Center Norman OK
   0859 AM CST Fri Jan 07 2022

   Areas affected...Northeast Massachusetts and Coastal Maine

   Concerning...Heavy snow 

   Valid 071459Z - 071900Z

   SUMMARY...Heavy snow is expected to continue across eastern
   Massachusetts for the next 1-2 hours before spreading northward
   across coastal Maine later this morning. Snow rates between 1-2
   inches per hour are possible.

   DISCUSSION...Regional radar imagery continues to show an organized
   snow band over eastern MA that has persisted for the past several
   hours. Under this band, several surface obs are reporting visibility
   down to 1/2 to 1/4 mile at times, indicative of heavy snowfall rates
   amid weak winds. Recent LSRs from the region lend credence to these
   observations with heavy snow accumulations up to 12 inches reported.
   Strong synoptic ascent within the left-exit region of a 100+ knot
   upper-level jet is expected to linger over coastal New England over
   the next few hours as the upper-level shortwave trough continues to
   shift northeast. Latest RAP analyses reveal a tight baroclinic zone
   between 850-700 mb just off the MA coast with vigorous warm air
   advection and frontogenetical ascent organizing mesoscale lift. The
   placement and evolution of the baroclinic zone, along with
   trajectories from recent guidance, suggest the stronger
   frontogenetical forcing will shift offshore for much of the day in
   the coming hours. However, warm air advection through the 850-700 mb
   layer will likely increase later this morning as winds strengthen in
   response to the deepening low. This warm advection regime should be
   rather broad and encompass coastal ME. Coupled with strong synoptic
   ascent, this may support heavy snow potential with snowfall rates up
   to 1-2 inches per hour later this morning and into the early
   afternoon.

   ..Moore.. 01/07/2022

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

   ATTN...WFO...CAR...GYX...BOX...

   LAT...LON   41567105 42307101 43177081 43767018 44206930 44416870
               44416821 44236798 43916842 43686904 43246979 42667000
               42196997 41726976 41216998 41217063 41267096 41567105