Note: I originally posted this for my personal web site - www.atkinsonweather.com. While it somewhat focuses on the forecast for the Merrimack Valley, Southern New Hampshire, and Northern Massachusetts, it also outlines the potential impacts throughout New England over the next several days.
The computer guidance has been hinting for a while that a storm would be developing off of the eastern seaboard around New Year's Day. A potentially significant storm system is still indicated, though its track and intensity remain in question. Hopefully this post will help outline the next few days for you.
One wave of precipitation will begin to move into the region during Thursday afternoon. This wave will bring scattered snow showers into the area during the afternoon. Less cold air will begin to move into the region during the afternoon, changing the precipitation from light snow to light rain along the coastline. Up to 1-3" of accumulating snow is possible in most of the Merrimack Valley, southern New Hampshire, and northern Massachusetts. More is possible in the higher elevations of southwestern New Hampshire and northcentral Massachusetts. Again, most of this snow will be on the lighter side (though it may come down briefly moderately/heavily) and travel shouldn't be a huge issue for your New Year's Eve plans.
On Friday, the system that comes through on Thursday will begin to phase and come together with another batch of moisture emerging off of the southeastern U.S. coast. Once these two systems come together, they will form a monster of a storm offshore. It will actually form well east of New England, so little impact will be felt here on Friday. We'll probably see a bit of a break in the action, with only occasional light flurries/drizzle or passing snow/rain showers.
Friday night into Saturday the forecast confidence goes downhill significantly. It appears as though the storm will mature significantly several hundred miles south of Nova Scotia. In fact, this storm may reach "bombogenesis" criteria, meaning it has strengthened significantly over a 24 hour period. However, the big (unanswered) question is where the storm goes from here. Indications are that the center of the storm will move northward toward Nova Scotia, then loop backwards into the Gulf of Maine, toward New England! This is extremely unusual, and definitely not something that is seen often. The exact position of the storm's center will make a huge difference, as bands of heavy snow will be rotating around the west and northwest quadrant of the storm, into New England. It appears as though the heaviest bands will probably rotate into Maine. Lighter snow showers may pinwheel as far south as the Merrimack Valley and eastern Massachusetts. While the impact will be significantly less in the Merrimack Valley/southern New Hampshire, accumulating snow is still expected, and it may even be plowable. However, the most significant snow appears to occur in Maine. The precise position of the storm in the Gulf of Maine will make a huge difference in our forecast. Therefore, it's important to stay tuned for further updates.
From there, the storm appears to continue its loop westward and southwestward into Sunday. The storm will continue to unravel, gradually losing strength. With the system nearby, expect a continuation of occasional snow showers. The steadiest of the snow would probably fall in the morning. At this time, it appears additional accumulation on Sunday would be light, though this is not etched in stone.
There are indications that occasional flurries and snow showers may linger into Monday or even early Tuesday!
The bottom line is that we simply aren't sure of the outcome of the second storm late Friday through the weekend and early next week will be. Check back for updates here throughout the next day or two as the forecast becomes more clear.