A cold front will move through the Philadelphia and New York City metropolitan areas this afternoon with more scattered snow showers expected over the region. While accumulation is expected to be a coating at most, the snow showers may produce a brief reduction in visibility at times. Winds will veer from the west to northwest at 5 to 15 mph. Temperatures will rise into the mid to upper 30′s over the interior and upper 30′s to lower 40′s along the coast.
High pressure will take hold tonight on through tomorrow with scattered cloud cover increasing to variable cloud cover by Thursday night. Winds will be from the north and northwest at 5 to 15 mph. Low temperatures will range from the lower to mid 10′s over the interior and upper 10′s to lower 20′s along the coast. High temperatures will range from the upper 20′s to lower 30′s over the interior and lower to mid 30′s along the coast.
On Friday, a major winter storm will develop along the Mid Atlantic coast and will have significant impacts on the Philadelphia and New York City metropolitan areas. There is significant uncertainty on the evolution of this storm, but the potential is clearly there for significant snowfall for all locations from Friday night into Saturday. However, this forecast is complicated due to the uncertainty of timing of a disturbance over the Southeast and a disturbance over the northern Plains. If timing is right than more snow than rain will develop for the Philadelphia and New York City metropolitan areas. In some models the phase happens so late that no significant snowfall develops for the region while other models suggest up to 1 to 2 feet of snow for Philadelphia, Pennsylvania on northeast through Boston, Massachusetts. This isn’t about models though but about physics and the timing of disturbances, which is always a difficult forecast. The map I have posted is a VERY preliminary idea of what could evolve here depending on several factors from how fast cold air can work back in and how warm the surface temperatures get ahead of the storm on Friday afternoon. Aside from the precipitation potential, there is also a significant potential for coastal flooding for Friday night into Saturday morning, which may be enhanced if the storm slows down on Saturday morning. In short, stay with NY NJ PA Weather because this forecast is likely to change and keep me on my toes. Temperatures for the forecast period will range from the lower to mid 30′s over the interior and upper 30′s to lower 40′s along the coast for highs on Friday and mid to upper 20′s for lows on Saturday morning.
After the storm exits, high pressure will be in control Saturday through Monday with tranquil weather conditions and moderating temperatures through the period. Temperatures on Saturday afternoon will rebound into the lower to mid 30′s for highs. Temperatures for Sunday will range from the upper 10′s to lower 20′s for lows and mid 30′s to lower 40′s for highs. Temperatures on Monday will range from the upper 20′s to lower 30′s for lows and mid 40′s to lower 50′s for highs.
A strong cold front will move through on Tuesday with period of rain and falling temperatures. Temperatures ahead of the cold front will range from the mid to upper 40′s for highs and then fall through the 30′s and 20′s in the evening.
Kelly, the NWS also said in their discussion that their confidence in their forecast is pretty low. After reading different posts and other sources, it seems like most want to bring some snow into Chester and Lancaster Counties.