SPC MD 111


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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

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

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...


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

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