The first official day of winter looks to be a mild one across the Northeast thanks to a large ridge just to the south of Bermuda. With a set up like this you can bet on a deep-layered west to southwest flow, and as such expect temperatures some 15 degrees above average.
Sunshine will be had to start the day with an increase in clouds during the afternoon, mainly in the form of high clouds early on, but by sunset the cloud deck will thicken and we’ll be overcast (at least to the south/west). This will signify the next system of import which will arrive overnight and bring a wealth of moisture along with it.
The surface low is expected to track from the Central Gulf Coast early Thursday afternoon to the Chesapeake Bay by midnight, and with an Arctic high pressure center over the Northeast lacking this will be a rain event for most area, and a soaking rain at that. Rainfall amounts of a half-inch to an inch will be common with localized amounts of nearly two inches.
The event comes to an end late Thursday with cooler air filtering into the region. Highs Friday should be several degrees lower as an upper-level trough sweeps across the Northeast. This trough may be able to generate a few sprinkles, but for the most part the area should be dry with a few breaks of sunshine in the afternoon.
Highs will gradually rise for Saturday, but with a chilly high centered over Maine the low-level cool air will push southward and bring highs closer to average. For Christmas Day we’ve brought highs up a bit to reflect more of a southwesterly flow ahead of an approaching shortwave trough.
Previously we had been concerned about the interaction with this northern branch feature and a disturbance moving across the Deep South. It now appears that the trough over the Northeast will be more progressive and effectively crush this energy as oppose to phasing with it, so a milder forecast is warranted. A stray afternoon shower isn’t out of the question.