A storm bringing blizzard conditions to the northern Plains will move eastward toward New England by tomorrow. The storm's center will pass well to the north of New England. This puts New England on the "warm side" of the storm. This will lead to plain rain showers across southern and central New England. Northern New England, however, could see more of a wintry mix.
With New England being on the warm side, warm air will work through the region aloft, however, cold air damming is expected to take place in northern areas. This cold air dam will continue to work its way southward while the warm air layer aloft continues to advance north. This is a classic setup for some mixed winter precipitation across areas of northern New England.
As the warm air lifts into northern New England, the initial dominant precipitation type breaking out Wednesday midday will be more supportive of sleet. However, as the warm layer becomes deeper throughout Wednesday, the dominant precipitation type will likely transition to freezing rain.
An extended period of freezing rain is expected for Wednesday afternoon through Wednesday night. Up to a tenth of an inch of ice accretion is possible in a broad area with some areas potentially getting up to 0.40 inches. One thing working to limit ice accretion is the fact that temperatures are expected to remain in the low 30s. With marginal temperatures, it will make it more difficult for ice to accumulate on surfaces such as tree limbs and power lines.
It's worth noting that this storm has trended colder over the last 24-36 hours. Should this trend continue, it could lead to more sleet, which would create less of a problem than freezing rain. The deeper the cold air layer is, the more sleet will fall.
The areas with the greatest chance of seeing an ice storm Wednesday afternoon and night will be the northern two thirds of Vermont, minus western Vermont, New Hampshire north of Concord and interior Maine. Areas south of these places will see plain rain showers.
The biggest question marks with this storm is how much freezing rain falls versus sleet and how much ice will be able to accumulate. It still looks like freezing rain will dominate, but sleet potential has been increasing. With marginal temperatures, the ice will have some trouble sticking to surfaces.
While snow will be very minimal in a vast majority of the region, northern Maine could see a general 3-6 inches before a change over to sleet and freezing rain.
TIMING
Wednesday morning: Wintry mix breaks out across northern New England.
Wednesday afternoon: Wintry mix turns from more sleet to more freezing rain.
Wednesday night: Heaviest precipitation, likely freezing rain.
Thursday: Scattered light showers throughout the day.