Winter storm to bring heavy snow initially to Vermont, Maine, New Hampshire before transitioning to mixed precipitation and potentially rain on the backside. Maine has the most potential for heavy snow, with the AFD out of GYX saying "...WINTER PRECIPITATION TO IMPACT NEW YEAR'S TRAVEL..." A difference with this storm is the potential for high winds, with gusts between 50 and 60 mph expected to impact Massachusetts.
A developing storm system will track through the Great Lakes into Canada, bringing rain to all areas of the Northeast and Mid-Atlantic regions. However, there is still a pertinent winter threat in the form of freezing rain and mixed precipitation. With cold air in place throughout the region, and the warmth arriving in warm air advection, there exists a possibility of cold air damming.
A strong storm over the Central Plains will move northeastward into Quebec by Friday evening. The storm will spread heavy snow and gusty winds to much of the Central/Northern Plains and Upper Midwest. Travel will be hazardous with slick snow-covered roads, especially in parts of the Dakotas where Blizzard Warnings are in effect.
A clipper system arrives in the region towards the latter hours of December 23rd. While overall impacts will be relatively light, there could be brief periods of heavy snow and reduced visibility. Currently, it appears that there is cold air to work with, pushing the rain/snow line down to NYC. The most "significant" aspect of this storm is that it may prevent a "brown" Christmas by providing snowcover to areas that haven't seen a major snowstorm in over a month.
Widespread rainfall totals are forecast to be 1 to 2 inches across the Southeast, with higher widespread totals of 3 inches in the Florida peninsula, and eastern North Carolina, Plus, locally higher rainfall amounts are expected in thunderstorms and where rain trains over the same location. Slight Risks of excessive rainfall/flash flooding are in effect on Thursday. Additionally, severe weather is possible along the Atlantic coast.
...Widespread rain and thunderstorms will spread from the Lower Mississippi Valley east and north through Friday.. A deep upper-level trough will continue moving eastward through the Plains, Mississippi Valley, and Ohio Valley through the end of the workweek. Gulf of Mexico and Atlantic moisture are expected to combine to create a heavy rainfall event for the eastern U.S.. Behind a secondary cold front on Friday, snow could mix in on the back edge of the precipitation across the Ohio Valley and into the Appalachians.
...Record warmth possible by Friday in the Mid-Atlantic region and Northeast...Gulf of Mexico and Atlantic moisture are expected to combine to create a heavy rainfall event for the eastern U.S. Widespread rainfall totals are forecast to be 1 to 2 inches across the Southeast and the Appalachians eastward, with higher widespread totals of 3 inches in the Florida peninsula, eastern North Carolina, and southern New England.
A series of strong storms will impact the northwestern coastline and mountains of the United States over the next few days. Currently, there are already numerous warnings out, and I-90 is actually closed in both directions over Snoqualmie Pass due to snowbound roads and spinouts. As per the Seattle/Tacoma AFD, atmospheric rivers of moisture will affect the region.