Significant snowfall Tuesday

An intense mid level wave is currently diving through the central plains, and will be passing through the Ohio Valley during the day tomorrow. At this time, the surface reflection is very weak, however model guidance agrees on a discernable low appearing tomorrow associated with the mid level low.

A piece of the polar vortex will break off and drift westward, allowing for the mid level low to rotate across LI and into the Gulf of Maine. Strong blocking, the theme of this winter, will continue to the north, preventing the low from making much northward progress. By Tuesday morning, surface low pressure will develop steadily along the NJ coast, and drift west-northwest across Cape Cod. There is some disagreement on the exact track of the low. The internation models, ECM, CMC, and UKMET are furthest SE, while the GFS and NAM are on the west side of guidance. The main difference being precipitation type on the coast, and dry slot issues in eastern MA.

Warm air advection will trigger the start of light to moderate snow across the region late Monday night into Tuesday morning. As the mid level low continues to wrap up to our SE, cold conveyor belt banding will bring additional moderate to heavy snow for a portion of New England through Tuesday evening. Where this banding sets up will dictate who gets the jackpot.

Even the southeast side of the model guidance gives a solid hit for western and central New England. At this point, confidence is building for a jackpot of 8"+, probably across central MA into central and SE NH. The GFS agrees the least with this senario, with highest totals across eastern NY and western New England, however it should begin to shift SE tonight, in accordance with the rest of the guidance.

Preliminary forecast for Keene,NH: 4" to 7"