Wednesday 8 a.m.
A large high pressure area over the Northeast maintains dry weather in the region. As the high pressure area drifts offshore, south winds will promote warming. Farther west, a flow from the Gulf of Mexico sweeps north toward the Great Lakes, and we see showers and thunderstorms developing. In this video, we show how the rain should eventually spread east as a cold front moves slowly from the Midwest toward the East Coast.
Once the cold front arrives in or near the I-95 corridor, many possibilities open up. Two of them are shown on these maps. Last night's GFS showed a low pressure area from then the Gulf states latching on to the front to bring rain to the Middle Atlantic states Monday. The European model shows the same storm but has it moving more slowly and expanding its influence farther north and west. This map shows those two solutions. I expect more changes on both models during the next few days.
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.