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ACUS11 KWNS 151850
SWOMCD
SPC MCD 151850
NYZ000-NJZ000-PAZ000-152245-

Mesoscale Discussion 1796
NWS Storm Prediction Center Norman OK
1250 PM CST Fri Dec 15 2017

Areas affected...Parts of southern/eastern New Jersey and Long
Island

Concerning...Heavy snow

Valid 151850Z - 152245Z

SUMMARY...Moderate snow is developing, with a 1-2 hour period of
heavy snow possible across parts of southern and eastern New Jersey,
mainly between 4-7 PM EST.

DISCUSSION...Large-scale lift supported by low-level warm advection
appears to be increasingly saturating sub-freezing thermodynamic
profiles across the northern Mid Atlantic Coast region.  Guidance
has been persistent in suggesting that increasing mid-level forcing
for ascent associated with an approaching short wave trough will
eventually contribute to increasing lift through the mixed-phased
layer most conducive to large dendritic ice crystal growth.  This is
expected to support increasing snow rates through mid to late
afternoon.

Heaviest snow rates may focus across portions of southern and
eastern New Jersey during the 21-23Z time frame, perhaps aided by
lower/mid tropospheric frontogenetic forcing which is forecast to
strengthen while shifting off the coast, generally south of Long
Island, by early evening.  Coupled with at least a modest increase
in moisture (precipitable water increasing in excess of .4 inches),
it appears possible that snow rates could approach or exceed 1 inch
per hour for a 1 or 2 hour period at a particular location.  This
seems most probable across New Jersey coastal areas from Atlantic
City through Toms River/Lakewood in the 21-23z time frame, but
portions of the greater Philadelphia metropolitan area may also be
impacted, as well as perhaps portions of Long Island by early this
evening.

..Kerr.. 12/15/2017

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

ATTN...WFO...OKX...PHI...

LAT...LON   40007515 40637344 40667225 39337326 38987471 39397544
            40007515



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