Nor'easter to lash Mid-Atlantic and Northeast with soaking rain, inland snow.
The week’s second major storm will slam the East Coast late Friday into Saturday.
Just days after a waterlogged system drenched the Mid-Atlantic and southern New England with 2 to 4 inches of rain and strong winds, another storm could bring a conveyor belt of moisture late Friday into Saturday. A developing nor’easter looks likely to lash the region, yielding an unwelcome slop of snow in the interior and the potential for record rainfall closer to Interstate 95.
Places from D.C. and New York City north through Boston could all be in line for the atmospheric fire hose, though uncertainty remains about how much rain falls and the exact timing.
Farther inland, accumulating snow is possible, with some indications of the first hefty snowstorm of the season in the cards for ski country in the northern Appalachians. Questions remain, however, regarding where exactly the rain-snow line sets up.
Ingredients for a storm
The instigating weather disturbance for this East Coast storm was bringing heavy snow to Oklahoma on Wednesday, where winter storm warnings were in effect. As much as 8 to 12 inches was expected just 100 miles northwest of Oklahoma City.
By Thursday into Friday, the disturbance will be invigorated by a pool of cold air at high altitudes dipping out of Ontario. The two systems will probably phase, or merge, their resulting synergy intensifying the disturbance into a hearty nor’easter that will ride up the coast.
The European model favors a more dramatic coupling of the two systems, as well as a track closer to shore. That would result in greater storm impacts. The American GFS model, on the other hand, doesn’t simulate the systems phasing, and instead allows the disturbance to continue barreling east-northeastward and only grazing eastern New England while sparing much of the interior. However, this model still predicts heavy rainfall in the Mid-Atlantic.
Impacts arrive late Friday and into Saturday
As the system swings east on Friday, a slug of downpours, showers and thunderstorms — some strong — are likely to trek through the South and enter the Carolinas. Late Friday into Saturday morning, rain probably will have reached much of the Mid-Atlantic. During Saturday, precipitation will streak northward, with a six-hour period of heavy rainfall likely from D.C. to New York City. That core of deepest moisture will pivot northeast throughout the day.
If the storm tracks close to the coast, cities in southern New England, including Providence and Boston, would also be likely to see heavy rainfall into Saturday afternoon. But expect lighter rains if the storm turns more to the east.
While the exact storm track is still coming into focus, temperatures will probably end up too warm for snow in the major East Coast cities. But snow is probable well inland thanks to cool air spiraling into the system from the northwest. How far inland the rain-snow line sets up will come into better focus in the coming days.'>>>
https://www.washingtonpost.com/weather/2020/12/02/noreaster-rain-snow-northeast/?