A major nor’easter will develop on Monday, shifting from the Mid Atlantic states towards New England. Periods of heavy rain will occur in New York City starting Monday afternoon and continuing through Tuesday morning, with localized flooding and gusty winds. A changeover to snow is *possible* on Tuesday, but the details on the changeover remain highly sensitive to the storms track and intensity.
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Periods of snow are likely in NYC from Friday evening through Saturday morning with light accumulations. More substantial accumulations will occur in the interior and higher elevations. Attention will then turn to another potential storm system early next week which may be larger and more impactful.
A weak storm system will approach the NYC area on Friday afternoon, with precipitation beginning as rain in the city and along the coast. A rain and snow mix will begin on Friday afternoon and evening. In the city, snow may struggle to accumulate even on Friday night with warm temperatures at the surface leading to melting.
By the early morning hours of Saturday, snowfall intensity will pick up while temperatures fall. Light snowfall accumulations will occur even in the NYC Metro area and along the coast. A trace to 2″ of snow is forecast in the NYC Metro before snow wraps up late Saturday morning.
Just a few miles inland from the coast – and in the higher elevations especially – snow will begin to accumulate later on Friday night and continue to do so into Saturday morning. Temperatures will fall quicker here than they do along the coast, with accumulations occurring more rapidly. 3 to 5 inches of snow is possible in these locations. Locally higher amounts can’t be completely ruled out, especially in the mountains of Northern New Jersey.
As snow wraps up on Saturday morning and afternoon, attention will turn to a more substantial storm system which may form early next week. Forecast model guidance has hinted at the development of a powerful coastal low from Monday into Tuesday. While the track of this system is still highly uncertain, this system certainly has a higher-impact ceiling than the light snow event on Friday.
The system is forming as a result of an atmospheric phase, or the combination of two storm systems in the mid and upper levels of the atmosphere. How quickly those two disturbances phase is the major question. A faster and more “clean” phase will bring the storm closer to the coast and lead to more notable impacts on the weather in NYC. A slower or sloppier phase will allow the storm to slip away, with the most notable impacts occurring in New England or perhaps even offshore.
These are situations where we like to use ensemble data in order to get a better picture of how the storm may play out. The GFS and European model both have ensembles, or a handful of members (30 and 51, respectfully) that are run in addition to the main weather model. This offers meteorologists some clues into the envelope of possibilities as well as what the most likely outcomes are.
In this case, ensembles are split in regards to the systems track and offer a wide range of possibilities regarding the storms strength. Some keep the system weaker and offshore, while others bring it much closer to the coast and strengthen it significantly leading to more notable weather impacts for our area.
We won’t know the details of this system with any confidence for a few days. Still, we’ll start to get a much better picture of how the storm may play out in the coming days and especially as we head into Saturday. Forecast model guidance generally begins to show less spread between possible outcomes as we get within 2 to 3 days of the storm system itself.
At the moment, the forecast carries a mixture of snow and rain from Monday evening into Tuesday along with the possibility of blustery winds. Stay tuned for further updates in the coming days.