Live updates: Winter storm takes aim at Washington, Philadelphia, New York and Boston – The Washington Post

For some areas, this is the biggest winter storm in the past few years, particularly in Boston, where the cold air will be abundant enough to allow for an all-snow event, with amounts piling up to around a foot, according to the National Weather Service.
Photos: Snow in Washington
Washington saw just 0.6 inches of snow all of last winter and seems poised to match that from this winter’s first storm.
While predicted to change to sleet and rain by midafternoon, steady snow is falling all around the District and its northern and western suburbs. A solid coating to an inch has already fallen, and roads are slick though passable in many areas.
Here are some scenes of the snow.
Weather Service warns of very heavy snow in the Appalachians to spread toward New York City later Wednesday
This area of heavy snow will expand and advance to the northeast Wednesday afternoon, reaching south central Pennsylvania.
By Wednesday evening, forecast models show a high likelihood of snowfall rates exceeding one inch per hour over much of northern Maryland, eastern Pennsylvania, northern New Jersey and as far north as New York City.
Snowfall of this intensity drops visibility below a mile or even a half mile and rapidly accumulates on roads. Travel will become very difficult from west central Virginia into southeast New York as the day wears on.
Line between sleet, rain and heavy snow will set up along I-95 from D.C. to New York
With East Coast winter storms known as nor’easters, it often seems as if Interstate 95, which connects Washington with Baltimore, Philadelphia, Wilmington, Del., New York, New Haven, Conn., and Boston, seems custom-built to serve as the rain/snow line. This storm is no exception, though there may be more sleet than rain in some areas.
The Weather Service forecast office in Philadelphia published a map Wednesday morning showing anticipated snowfall that indicates how sharply amounts will fall off just to the east of I-95, and climb to the west, as if the highway itself is somehow halting the progression of warm air inland.
In New York City, the highway could also serve as the boundary between a snow and sleet mix, and all snow, with snowfall totals climbing to the west of the thoroughfare.
Sharp dividing lines between snow and mixed precipitation are typical with these storms, since they draw in relatively mild air from the Atlantic Ocean, which moves in just above a layer of cold, dense air at the surface. The result is snowflakes that melt as they move through the mild layer and then refreeze into ice pellets as they fall through the shallower cold air. If the cold air is eroded at the surface by onshore winds then the precipitation will become plain rain.
It can be tough for such a warm air layer to push far inland, and this means that I-95 is more often than not the battle zone between precipitation types.
Snow begins in Washington, with a light dusting in some areas already
Between 9 and 10:30 a.m. Wednesday, snow rapidly spread over the D.C. area, with sleet mixed with the snow south and southeast of the city.
Some areas had already seen a dusting within an hour of the snow beginning, and untreated roads could become slick into the early afternoon.
Temperatures throughout the region were in the upper 20s and low 30s, cold enough for snow to accumulate.
The snow is expected to transition to sleet and freezing rain and then plain rain as the afternoon wears on, but up to a couple of inches could fall in Washington and just to its west, with greater amounts possible in its colder suburbs west and north outside the Beltway.
Well to the southwest of Washington, toward the mountains, two inches of snow has already been reported in Front Royal.
Major snowstorm on the way for the New York to Boston corridor
While the winter storm is likely to bring a messy, wintry mix to Washington, Baltimore and Philadelphia, cold and dry air is most abundant and entrenched across New England. The region from New York City to Boston, including the Hudson Valley, Long Island, all of Connecticut, Rhode Island and most of Massachusetts, is facing a major snowstorm during this event.
Weather Service forecasts show between a foot to a foot and a half of snow falling throughout this region, though accumulations in New York City itself could be slightly lower if any sleet mixes in at the height of the storm. Winds will also be strong in New York, with gusts to 55 mph possible.
Given tremendous atmospheric lift associated with this storm, thundersnow is possible, especially in New York and southern New England. Computer models are also pointing to the likelihood of a band of extremely heavy snowfall pivoting over Upstate New York, which could bring nearly two feet of snow to Albany.
It’s unusual for Boston to see a foot or more of snow before Christmas, given the presence of relatively mild ocean waters in the Atlantic. However, 2020 appears to be headed toward being an anomaly, with around a foot potentially falling at Logan Airport.
D.C. area forecast calls for mess of snow, ice and heavy rain
From snow, to sleet, to heavy rain, D.C. and its nearby suburbs will see a little bit of everything from Wednesday’s Mid-Atlantic storm.
Light snow is first on the menu Wednesday morning before a transition to sleet and freezing rain during the early to mid-afternoon, and then to plain rain by late afternoon. After periods of heavy rain into the late evening, precipitation could change back to snow before ending around midnight.
The District and areas just to the west are under both a winter weather advisory, due to the possibility of slick roads when snow and sleet falls, and a flood watch.
Into Washington’s far north and west suburbs, including Loudoun, northwest Montgomery and western Howard counties, a longer period of snow changing to icy precipitation will bring more significant accumulations and hazardous driving conditions. This area is under a winter storm warning.
Just about an hour west and northwest of Washington, toward Interstate 81 and the mountains, even more snow is expected, and some areas could receive well in excess of six inches.
East of Washington, although a brief period of snow and sleet is possible, mostly rain is expected. The rain could be heavy with 1 to 2 inches possible.
Published at Wed, 16 Dec 2020 17:47:00 +0000
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