Here we go again! Another significant snow event is coming on Saturday to the Mid-Atlantic region from the PA/MD border across most of central and eastern Pennsylvania, northern New Jersey and southern New York State - and this includes the northern and western suburbs of Philly and New York City. Last weekend it was the Eagles football game that showcased to the nation a Philly snow event and tomorrow the Army/Navy game may do the honors. In fact, this will be the third accumulating snow event in just six days for the Philly metro region which is quite an accomplishment for any time of year, and especially for this early in the winter season. Low pressure will move from the Lower Mississippi Valley on Saturday northeastward to just off the Mid-Atlantic coast by early Sunday where it will strengthen. Snow will develop in the I-95 corridor on Saturday morning and continue through the day north of the PA/MD border before slightly milder air changes the snow to a wintry mix Saturday night that'll add a layer of ice on top; however, that changeover to a wintry mix won’t happen until significant snow accumulations occur in the N and W suburbs of Philly and NYC.
This will be a “conventional” snow event in the Philly and NYC metro regions in that there will be higher snowfall amounts as one goes farther and farther north and west of I-95 and lesser amounts closer and closer to the coastline. Accumulations on Saturday are likely to fall in the 3-6 inch range across most suburban locations N and W of Philly (e.g., Bucks, Montgomery and Chester Counties) with 1-3 inches in and around the immediate Philly metro region (e.g., Delaware and Philadelphia Counties), and an inch or less at the Jersey Shore. Elsewhere, 6-12 inches of snow can fall from northeastern PA (including the Pocono Mountains) to areas not far to the N and W of the NYC metro region, and 3-6 inches are likely in the immediate NYC metro region. Farther south, this does not look like a significant snow producer in the immediate DC metro region.
The Canadian forecast model has done a good job with the recent snow events and it certainly suggests significant snow will fall just to the N and W of Philly and NYC and also as far south as extreme northern Maryland near the Mason Dixon line. The forecast map is for early tomorrow evening and it depicts heavy snowfall just to the N and W of Philly and NYC. A wintry mix is likely for awhile later tomorrow evening in the N and W suburbs, but the damage will have been done with respect to snow accumulations.