The National Weather Service says 5 to 8 inches of snow could fall in Philadelphia starting Tuesday afternoon and into Wednesday.
A winter storm warning will kick in for Philadelphia and it suburbs around 2 p.m. and last through the night.
Six inches of snow is forecast for parts of western Pennsylvania, with higher amounts expected in the Erie area.
PennDOT officials in the Philadelphia region plan a news conference for Tuesday morning to discuss plans for dealing with the coming storm.
NJ braces for a foot of snow in some areas
The National Weather Service has put all of New Jersey under a winter storm warning for a stretch of Tuesday and Wednesday.
Forecasters expect the snow will begin falling on the southwest part of the state in the afternoon, then will gradually move toward the New York City suburbs by evening.
Every part of the state is expected to get at least 5 inches. The highest totals, of a foot or more, are expected in the northeast part of the state.
The state Transportation Department began pretreating roads on Monday.
