There has been a good deal of uncertainty this week over whether the Northeast, especially the coast, would experience a white Christmas this year. Earlier in the week, guidance was suggesting a warm system with a low pressure moving through the interior Northeast, bringing mostly rain and some higher elevation snow to the region. As the week progressed however, the model runs trended the center of low pressure further to the east, keeping it offshore and allowing colder air to work its way in and bring a white Christmas to a much larger portion of the region.
Whenever predicting snow for the Northeast, it’s important to focus on the track of the low because that determines the placement of the rain/snow line. If the low takes a track directly over the region, snow will only fall to the north and west over the interior Northeast. Now if it takes an offshore track with the low being at least 100 miles off the coast, you’re much more likely to have an all-snow scenario, even down to the coastline. Based on the latest trends, especially with some of our mesoscale guidance now that we’re inside 84 hours of the event taking place, we’re thinking that the low will take a track between these two. It will likely move just offshore of the coast, allowing for the heaviest snow to fall just inland of the I-95 corridor, and rain changing over to snow for some of the major east coast cities.
We’re going to be watching two separate pieces of energy on Sunday: one over the Midwest and the other near the Southeast coast. These two will approach each other and phase, thus becoming one storm just off the Northeast coast Sunday night, the night of Christmas Eve. The main event with this storm for the Northeast will be from early Monday morning through Monday evening. Then the entire storm will quickly depart and head toward the Canadian Maritimes.
Storm one is the one that will bring snow from the Northwest to the Ohio Valley. Once it gets that far east, this storm will weaken and its energy will transfer to a new low pressure just off the Mid-Atlantic coast.
On Saturday, a light to moderate snow will break out from the Cascades of Oregon through much of the intermountain West. Since this is a relatively fast-moving system, snowfall totals won’t be as significant as the storm earlier this week where over three feet of snow fell in some locations of Montana. Then by Sunday, the snow will have already made its way to the central Plains. That light swath of snow will extend from northeastern Colorado early Sunday morning through the central Great Lakes and Ohio Valley by the evening. It is at this time when the snow will begin to wind down due to that transfer of energy, leading to storm two for the Northeast.
Snow will begin to move into much of Pennsylvania, New York, and into Southern New England Sunday evening. The snow will then expand and increase in intensity during the early morning hours of Christmas Day. At this point, snow will impact most of New England and New York while winding down further west across states like Pennsylvania. The snow will then quickly clear out from New York and portions of Southern New England by Monday afternoon while continuing in central and northern New England. The snow should dwindle down for everyone during the evening hours.
Zooming in at the coast and along the I-95 corridor, from Washington, D.C. through Philadelphia, we expect mostly a rain event to take place. A few snow showers will be possible before the storm moves out, but it shouldn’t amount to very much. A bit further north from New York City to Providence to Boston, cold air will work its way into the storm just in time for rain to changeover to a period of steady snow Monday morning and afternoon, making for some light accumulations possible. Once you get north and west of the I-95 corridor, mostly snow can be expected, and more moderate to even heavy accumulations will be possible. Travel issues are likely where all snow is expected, and driving/flying is not advised during the peak of the storm on Monday. Plan ahead now if you’re thinking about traveling on Christmas Day, as you may have to make some adjustments. Thankfully, the storm will be quick moving, so while a good swath of the region will have snow falling at a good rate on Christmas, that snow won’t last very long.
Accumulations along the I-95 corridor from New York City to Boston should be on the light side, with a general 1-2 inches of wet snow expected, but not too far inland we’re forecasting up to half of foot possible. Stretching from the Midwest into the interior Northeast, snow showers will accompany this storm, and again could lead to light and moderate accumulations of up to 4 inches in localized areas. Not a huge deal, but will likely disrupt things just enough to make for some travel headaches if you plan on venturing out. In eastern Maine, however, up to 8 inches of snow may fall.
If you’re in the lucky locations expected to receive snow, we hope you enjoy the white Christmas. For the rest of you, we hope you still have a very merry Christmas, even if the grass is a bit greener!