Hot, humid weather will the rule this weekend from Illinois or Wisconsin south to the Gulf Coast. This is nothing new in the South, but will represent the longest period of very warm to hot weather (so far) this summer. Meanwhile, most of New England should be dry and at least partly sunny with afternoons in the comfortable 70s. Between the two air masses, there will be an unsettled contentious zone where thunderstorms will develop. This video may give you a better picture of what to expect.
The next map shows the pressure pattern in the Northeast. It is very busy map with subtle looking but important boundaries. For example, the purple line in the east marks the boundary between air coming in from the ocean and a southwesterly current of warmer air. That boundary was the scene of showers and thunderstorms when it was in the middle of Pennsylvania yesterday, and was associated with rain that moved through the Hudson Valley early this morning. It could become the breeding ground for new showers and thunderstorms this afternoon and tonight along or near the I-95 corridor.
This map shows the split flow that is predicted to be in place on New Year's Day. Note how the flow reaching northern Pennsylvania originates far north in Canada, whereas to flow aimed at Virginia comes from Mexico.
The maps I searched for were from December 1960. I was 13 and was thoroughly overjoyed when Philadelphia got 14.6 inches on Dec. 11 and 12. Schools were closed for three days, something that did not happen again until the Blizzard of January '96.
At midnight, the temperature will be in the 50s to low 60s from Virginia to Southern New England... more like late spring than Christmas time. Meanwhile, cold air will be advancing into western parts of Pennsylvania and New York, driven by strong winds. Earlier, this "cold" air mass looked like it would be more potent than it has turned out to be. This map shows the pressure pattern and some temperatures at 9 a.m.
Temperatures are likely to be in the 50s from Boston to Washington, D.C., during the nighttime hours of Christmas Eve. Dry chillier weather will arrive during Christmas Day, with dry weather lasting until at least Saturday.
This picture, which may or may not have been taken very recently, has a red dot near the North Pole. I cannot confirm that a red dot is there on the ground or that it means anything. We will monitor the area for any signs of activity and advise everyone to maintain the spirit of being nice and not naughty.
Rain with areas of fog should spread from Virginia to New Jersey Monday or Monday night then spread into New England for Tuesday. From the mountains of northeastern Pennsylvania into the interior of New England this could at least start as snow or ice. The GFS for 1 AM New Year's Day looks interesting. See the map below. Whether or not this storm develops and where it will snow or rain cannot be precisely predicted two weeks in advance using these models.