Wednesday, 9 a.m.
A southerly flow of increasingly moist air is spreading up the I95 corridor, where the dawn was greeted by dreary dullness and dim, drab drippiness from Maryland to Massachusetts. There are also some showers from western New York to Ohio along a cold front that will reach the East Coast this evening. When that cold front arrives, it will usher in a dry air mass that pulls back the curtain of clouds to reveal brilliant sunshine that plays off the multicolored leaves in the Northeast from tomorrow into the weekend.
In New York City and Philadelphia, typical afternoon temperatures are well up in the 60s at this time of year. Nights cool to about 50 in the cities, but well down in the 40s in many suburbs. The air masses in place from tomorrow through Saturday will bring temperatures that run about a half-dozen degrees below those long-term averages. Saturday morning is apt to be frosty in the colder suburbs from Washington, D.C., to New York City and below freezing in upstate New York and much of New England's interior. However, a strong southwesterly flow of warmer air could boost temperatures to 70 degrees in these areas on Sunday afternoon.
A strong storm is likely to cut through the Great Lakes Saturday night and Sunday, and its associated cold front will trigger showers and even thunderstorms. However, the air coming in behind that storm should not be as chilly as the air that follows this week's fronts. The reason: this week's upper air flow into the Northeast can be traced back to northwest Canada. Next week's main upper air current looks like it will be straight west to east. The video has more.
it appears a storm will form the Southeast and trek toward eastern New England this weekend. Current models suggest this will turn into a mostly rain event in the I-95 corridor...
This map shows a draft of our starting time lines and expected accumulation from tomorrow's quick-moving East Coast storm.
A storm that has brought hardship and danger to parts of Texas and Arkansas with an assortment of ice and snow will send a swath of snow northeastward today and tonight. Here is a map showing our overall estimates as of 10 a.m. ET:
That could lead to tough travel at the end of the weekend. This map for Sunday at 7 p.m. ET shows where those troubles could be (north of the line with the label "snow rain line.")
This table shows the ensemble means for the next two weeks at Philadelphia: It suggests that whereas it does turn cold, any snowfall looks quite limited.
It is too early to be confident about any forecast for Christmas Day (or even the week before). However, the GFS model does go out 16 days, and it has a cold look for the Northeast exactly one week before Christmas.