Monday 10 a.m.
A stalled storm east of New England is creating a cloudy, wet regime for the Northeast. During the weekend, incessant rain dumped more than 8 inches in parts of Maine. Rain was much more spotty farther south and west, but many places had at least a couple of showers and several lines of thunderstorms developed yesterday across New York and Pennsylvania. As of midmorning, there was a concentration of showers (some heavy) from the southern Catskills down across northern New Jersey and right into the New York City area. An umbrella or raincoat would be quite useful.
The storm is unlikely to leave any time soon, but it may change shape. If the axis of lowest pressure shifts from its current east-west orientation to one that is more north-south, drier air will be able to spread from east-central Canada southward into much of New England and the Middle Atlantic states. That's the trend suggested in this video.
In this picture, you can see the conveyor belt of moisture extending from well east of northern New England all the way to the eastern Great Lakes. However, there is dry air (as shown by clear skies) farther north in Eastern Canada. This is what would move southward if the storm system changes orientation.
For next weekend, there are signs that an upper-air ridge will build toward the Northeast and Great Lakes regions. If true, the weather would become sunny and much warmer!
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.
As the flow aloft becomes southwesterly, mild moist air will spread northeastward from the Gulf States. In summer, this creates a hazy, very warm and humid scene for the Northeast. Now though, the warmth is slowly drained away as the moist mild air advances over cold ground. With temperatures near the saturation point, clouds form.