Throughout the week we’ve discussed the first shot at widespread snow near the I-95 corridor. While guidance had backed off from that outcome over the last day or two, there appears to be a different trend today with our newest mesoscale modeling. An area of low pressure is currently developing over the Gulf of Mexico, drawing in very cold air from the north all the way down into the Gulf Coast region. So much cold air has been drawn in that snow is breaking out across southern Texas this afternoon, and will continue to spread into parts of Louisiana, Mississippi, Alabama and Georgia tonight, tomorrow, and into early Saturday. Temperatures will be cold enough to even bring some light snowfall accumulations into these areas. Pretty unusual for early December.
Later tomorrow this low pressure will begin to strengthen, gather more moisture, and head in a northerly direction, bringing rain and snow into parts of North Carolina, Virginia and the coastal Mid-Atlantic as we head into early Saturday. By Saturday morning and afternoon, light, wet snow can be expected from Richmond, to Dover, to New York City all the way up to Boston. This snow is not expected to be heavy, but the further east you are, the heavier it will get. With temperatures slightly above to just around freezing, it’s likely not all of this snow will stick at first, but as it continues to fall we do expect some light accumulations on grassy surfaces and car-tops. It’s once you get into the southern New England and northern New England regions where temperatures will be solidly at or below freezing, allowing more consistent accumulations of 1-3+ inches.
As our storm heads north at a fairly fast pace, snow will expand further west and become a bit heavier. Right now, we think the area with the best chance of receiving 3+ inches of the white stuff extends from Boston to Concord to Bangor. This will happen overnight Saturday into early Sunday.
While we’re only a day or two from the actual event taking place, as always with the weather, there is still some uncertainty. While the ECMWF hasn’t been sold on this outcome this last few days, this afternoon’s 12z run came in much more aggressive, making it possible that we upgrade totals later tonight or tomorrow. Meanwhile, short range guidance is even more aggressive than ECMWF in some cases, bringing flakes back into parts of central PA and upstate New York. For the time being, our team likes a slightly less aggressive forecast until we see some more consistency, keeping light accumulations from Richmond to Washington to New York City, and heavier accumulations near Hartford and then up into Boston and eastern New England. With some blocking overhead, we may even see our system slow down for a time on Sunday, making 5-6+ inches possible across parts of New Hampshire and Maine. We’ll have another update on this tonight or tomorrow morning, with adjusted totals if needed. Stay tuned.