Mesoscale Discussion 0111
   NWS Storm Prediction Center Norman OK
   1225 PM CST Wed Mar 07 2018

   Areas affected...New Jersey...Southeast Pennsylvania...Southeast New
   York...Southern New England

   Concerning...Heavy snow 

   Valid 071825Z - 080030Z

   SUMMARY...Moderate to heavy snowfall is expected to continue across
   parts of southeast Pennsylvania, New Jersey and New York City this
   afternoon gradually spreading northeastward into southern New
   England.

   DISCUSSION...The latest surface analysis shows a 995 mb low about
   110 statute miles east of the southern Delaware coast. A pronounced
   dry slot evident on water vapor imagery is located just off the New
   Jersey coast. Water vapor imagery shows rapidly cooling cloud tops
   over the last couple of hours in the southern part of the MCD area
   and lightning strikes are also noted. This is due to the approach of
   a band of large-scale ascent associated with a negatively-tilted
   upper-level trough moving through the Mid-Atlantic. This combined
   with strong isentropic ascent oriented parallel to the coast and
   just inland is maintaining a band of moderate to heavy
   precipitation.

   Although surface temperatures from New Jersey north-northeastward
   into southern New England are generally just above freezing,
   temperatures have cooled a couple degrees over the last hour. This
   dynamic cooling has resulted in a change-over from rain to snow in
   the New York City vicinity over the last hour. The heaviest snowfall
   is occurring within a band oriented from south-southwest to
   north-northeast across New Jersey and southeastern New York. This
   band will continue to spread north-northeastward into southern New
   England this afternoon. Snowfall rates of 1 to 2 inches per hour
   will be common. A few spots could receive snowfall rates of more
   than 2 inches per hour especially related to convection. Locations
   in far southeastern Massachusetts near Cape Cod will likely remain
   rain through early evening.

   ..Broyles/Hart.. 03/07/2018

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

   ATTN...WFO...BOX...OKX...ALY...PHI...

   LAT...LON   40507320 39827419 39497519 39877578 40547564 42067372
               42587157 42557086 42237057 41807059 41337106 41007213
               40507320