The models this Thursday have suddenly trended towards a weak coastal storm closer to the coast. The models this week have kept this low-pressure far enough offshore to bring zero impacts to the Mid-Atlantic and Northeast. However, every new model run that has come in this Thursday have shown a noticeable trend to the west in terms of the track of this low. Because of this westward shift, impacts from this weak and developing coastal storm are likely.
— John Homenuk (@jhomenuk) December 14, 2017
At the same time, a weak area of low pressure will develop off the Carolina coast, leading to the formation of snow showers across portions of Virginia back into West Virginia. As the low strengthens and organizes, the snow will become more focused over a small region and become heavier. A moderate to perhaps heavy snow will impact the Washington DC, Baltimore, and Philadelphia areas Friday afternoon. The DelMarVa will also be in play with the snow, although southern Maryland on the DelMarVa may experience rain due to above-freezing temperatures. Snow will also overspread into southern New Jersey during the afternoon hours, where a heavy band of snow may develop somewhere over this region.
The evening commute is looking to be a tricky one for most of the DelMarVa, New Jersey, and into Long Island, including New York City, as the low moves northeast. During the evening, the snow will clear out across the Mid-Atlantic, but it will continue on into Long Island. Some snow may also sneak into the southern coast of New England. The greatest chance for snow in this area is Cape Cod and the islands Friday night. By early Saturday morning (3am), impacts from this storm will come to an end as it gets picked up by the jet stream and zooms out to sea.
Snow accumulations will generally be light because it is a quick event, with snow lasting up to six hours. Up to three inches of snow will accumulate for most areas, especially closer to the coast. Localized areas in Delaware and southern New Jersey may have the chance at topping off at three to five inches.