The NWS is pretty much all-in for a major snowstorm at least from Philly to NYC and all points NW of that line. My NWS point-and-click gives me 15" of snow in the Edison area and for Montgomery it's 14" and it's 15" for the Hoboken/JC/Manhattan area. They could be wrong, but they're fairly bullish as am I. Just too much cold air in place to get rain too far inland, according to most of the mets I've been reading.
From the NWS-NYC:
Given the supply of low level cold air and unlikelihood of
warmer air intruding aloft, this event looks to be all snow for
just about the entire region, except maybe the south shore of
eastern Long Island for a time. Too early to get into the
mesoscale details here,
but confidence in significant snowfall
amounts over 6 inches continues to increase, with potential
for over a foot of snow in areas that experience the best
mesoscale lift and snow growth NW of the low track.
NE winds should also be quite strong along the coast due to the
pressure
gradient between the strong high to the north and the
developing low, as high as 25-35 mph with gusts up to to 45
mph, causing considerable
blowing and drifting of snow and at
least near
blizzard conditions.
From the NWS-Philly (their comment about "NWNJ" below includes Mercer/Somerset/Middlesex, as all of their point and clicks give all snow; need to get towards Freehold up to Keansburg and east of there to get into a fair amount of rain, followed by a lot of snow):
In terms of the sensible weather and impacts with the storm,
again, still early to be confident in the details but expect
precip to develop SW to NE around the late morning early
afternoon time frame. Most areas should at least start as snow
due to the cold airmass in place with the possible exception
being southern Delmarva east toward south coastal NJ where it
should be mostly rain. In fact a period of at least a few hours
of snow, possibly moderate to heavy at times is
likely near and
especially north of the urban corridor by the latter part of
the afternoon. The challenge then becomes by around the early
evening time frame...if the low tracks farther north/west along
the coast then over over Delmarva
mixed precipitation and rain
could make it into SE PA east through Ocean County...basically
through the I-95 corridor including Philly and possibly even a
bit farther north. This would limit storm total snow. A track
farther south could
mean snow amounts well over 6 inches even
into places like Philadelphia. Again confidence on these details
is low but one way or another it will be quite messy.
To the
north though through the northern and western Philly suburbs
through the remainder of eastern PA and NW NJ confidence is
higher in larger snow amounts. Amounts cold potentially
exceeding a foot in places. The other concern that needs to be
highlighted with this storm is winds. NE winds gusting 40 to 50+
mph look increasingly
likely near the coast and this could be
enough to result in some
power outages.