PM All Zones Update: Interior winter storm Tuesday night

A low pressure area is expected to shift from the Mississippi Valley into the Eastern Great Lakes on Tuesday, bringing enhanced lift and aiding in the development of precipitation over much of the Ohio Valley and Northeast. Much of this precipitation will be driven by a process known as Warm Air Advection. In other words, warming air surging through multiple levels of the atmosphere will be the impetus for precipitation.

It will also serve to ensure that most areas in the Mid Atlantic and near the coast warm up sufficiently for precipitation to fall as rain. Inland, however, a different story will evolve. Cold air from a high pressure to the northeast will settle near the surface, allowing temperatures to fall into the upper 20’s and lower 30’s. A gradual warmup is expected to occur from southwest to northeast, but not before some light wintry precipitation even in parts of Pennsylvania and Northwest NJ.

NAM model showing the evolution of a winter storm in New England on Tuesday and Wednesday.

NAM model showing the evolution of a winter storm in New England on Tuesday and Wednesday.

Freezing Rain Advisories have been issued by the NWS for those areas on Tuesday, with the anticipation of a few hundredths of an inch of ice accretion. While the event is expected to be mostly “low impact”, even a few hundredths of ice can cause slippery roadways and some travel problems if surfaces are left untreated.

The event will become more significant the further northeast one travels — especially in parts of Connecticut, Eastern New York and New England (there is a specific zone update out for those areas). Here, a more significant period of wintry precipitation is possible — including freezing rain, sleet and snow. An associated winter weather impact map has been issued by our forecasting team this afternoon. Snowfall totals in our zones are expected to remain relatively negligible.

Elsewhere, precipitation is expected to fall mostly in the form of cold rain — and much of Tuesday afternoon and evening will be quite dreary. Temperatures will push above average as the storm pulls through the area, even as a low pressure area redevelops off the coast of Southern New England early on Wednesday. Gradually on Wednesday, the system will evolve eastwards and depart the area.

Map of expected impacts (general) from Tuesday into Wednesday.

Map of expected impacts (general) from Tuesday into Wednesday.

More calm and tranquil weather will take over as the week goes on towards its latter stages. Temperatures are expected to average above normal for the most part, with a propensity for warmer than normal air continuing into the early and middle part of the work week ahead (next Monday onward).

Stay tuned for a subsequent long range outlook which is forthcoming this afternoon and evening. We’ll detail the expected pattern evolution as we move towards January and February!