Well today’s the big day as our nor’easter forms just off the Mid-Atlantic coast and brings wintry weather to a large portion of the Northeast, affecting millions of people between today and Friday. This morning, we have already heard reports of accumulating snow in the Washington, DC area, and that will likely be the story in other major cities up the I-95 corridor as the snow tracks to the north as the day progresses.
Along the I-95 corridor, snow will be falling this morning from Washington, DC up through Philadelphia. The best risk for several inches of accumulating snow will be west of these cities into the higher elevations while warmer air tries to invade from the coast. That warmer air will eventually win out during the latter half of the day as the snow transitions into sleet midday in these cities, although the snow should last through the mid-afternoon in Philadelphia.
To the north into New York City and the greater area surrounding the Big Apple, flakes will begin to fly around noon, and the accumulating snow won’t take too much longer to begin afterwards as we expect that to take place by the mid-afternoon. This comes as a heavy band of snow drifts to the north, likely producing snowfall rates of at least 1-2 inches per hour for several hours thanks to large-scale lift in the atmosphere. There may even be the risk for thundersnow, especially in New England. It is worth noting how much of eastern and southern Long Island will just experience rain while some wintry precipitation mixes in along the Jersey shore. Now in and around New York City, after several hours of snow comes down, we do expect that to transition into a wintry mix of either sleet or freezing rain after sunset. That should then turn into rain showers by midnight while a dry slot of air works into the occluded storm.
In the Boston area and general southern New England, the snow won’t begin until the early to mid afternoon, which will be just in time for the evening commute home. Across the southern coast, heavy snow will coincide with the late-afternoon while in Boston and central portions of New England it will wait until the evening or the first half of tonight. A brief period of snow will be possible across the Cape and surrounding islands, but given the fact these areas are surrounded by the warmer waters of the Atlantic Ocean, rain will definitely be the main story. Across southern New England as a whole, the heaviest of totals will be found in northern Connecticut and western Massachusetts thanks to the colder air in place and the longer time period of falling snow. After 6pm the earliest, the rain/snow line will begin to surge northward through southern New England, reaching northern New England by early Friday morning.
Freezing rain will be a concern in parts of the Northeast, especially from south-central Pennsylvania through central New York and into the southern Berkshire Mountains, especially overnight tonight. This will make roads slippery, so traveling is not advised.
Now across the interior Northeast, this will be an all-snow event for most areas. This morning, snow is falling or will be falling from the southern Great Lakes through much of Pennsylvania and the higher elevations of the Mid-Atlantic. As we get into the afternoon, however, the rain/snow line will begin to become present in parts of the region as it tracks in from the south and east. This will lead to a wintry mix of freezing rain and sleet to much of eastern and southern Pennsylvania in addition to the central Appalachian Mountains.
Meanwhile to the north in New York, snow will begin in the early afternoon across southern and western portions of the state before the central and northern portions experience the snow closer to the evening hours. It’s not until the overnight hours, though, when a heavy band of snow develops on the backside of the low pressure, affecting a fairly large region of New York and extending into western Pennsylvania. This band will be a rather efficient producer of snow, dropping totals of likely 1-3 inches an hour. While the western and northern parts of New York experience snow throughout the night, it will evolve into freezing rain or rain showers across central and southern New York. Then by sunrise Friday, the precipitation will come to an end from west to east as a final band of snow clears out of eastern New York during the first few hours of the morning. Lake effect snow may then develop beginning Friday afternoon near Lakes Ontario and Erie, which will produce additional snowfall not related to this nor’easter.
Finally in northern New England, this will also be an all-snow event for most. Unlike the rest of the Northeast, the snow won’t begin in this region until the evening hours after sunset, but it will be going strong overnight as that snow band comes in from the south, delivering several hours of heavy snowfall. Now as the night progresses, a dry slot of air will try to usher in warmer air, so that may lead to a transition of wintry precipitation across southern and coastal parts of the region. The snow or wintry weather will persist into Friday morning before that final band of snow sweeps through the region midday Friday. Lingering snow showers may be present during the latter half of the day.