A band of snow that produced a coating to an inch or so outside the beltway to the west of the District of Columbia this morning eroded while moving northeast towards southeastern Pennsylvania as it encountered a deep layer of dry air entrenched in this region. Dew points continue to hold at dry levels (in the teens) at mid-day across SE PA, but the atmosphere will become moist enough by the mid-to-late afternoon to allow for the development of a mixed bag of precipitation including sleet, snow and rain. Once the precipitation begins, temperatures will drop a few degrees at the onset due to some evaporational cooling effects. The mixed precipitation should last for a few hours in SE PA before a changeover to plain rain occurs later tonight. The rain will continue overnight and into tomorrow morning and some of the rain can come down hard at times. Snow or mixed precipitation should reach the New York City metro region late this afternoon or early this evening and continue there until late tonight at which time a changeover to plain rain is expected. Snow can come down quite heavily for awhile this evening in the NYC metro region after the initial round of mixed precipitation drops temperatures a few degrees. Snow and ice accumulations on the order of a trace to a couple of inches are possible from later today into later tonight in both the Philly and NYC metro regions, primarily on grassy surfaces to the N and W of the two cities. The DC region may have some sleet mixed in later this afternoon when precipitation resumes in that area, but the main form from here on out down there will be plain rain.
Looking ahead, despite a brief warm up tomorrow just ahead of a strong cold frontal passage, this overall winter-like pattern will continue for the second half of the week and beyond with the next threat for some snow or snow showers coming late Wednesday night or early Thursday. An even bigger storm threat is possible early next week. The good news – Opening Day is only 2 weeks away.