Winter Storm Watch...
The National Weather Service just issued a Winter Storm Watch for Interior MA and Southern NH for late tomorrow night through midday on Thursday. Hard to believe we are talking about a Winter Storm with highs in the middle 40s today but later tonight the cold will be sliding in and highs tomorrow will be nearly 10 degrees colder in the 30s. The high pressure cell that delivers this cold will be centered to our north in Canada. At first it will be located in a good spot for snowlovers but as the event unfolds, the high will be sliding to the east allowing milder ocean air to work in. With that said, this looks like a classic cold air damming situation for the interior and especially locals in Northern New England. The heavier cold air will continue to drain south on lighter northerly ageostrophic winds. While at the coast, a stiff east wind will transport that marine air inland resulting in mostly rain for much of Eastern MA. The cold in the interior will be a deep enough layer at the start for a burst of snow at the start N&W of Boston (S&E all rain). But as the morning commute progresses, warm air from aloft will be chewing away at that layer of cold and all snow will change to sleet and eventually rain or freezing rain for Northern Worcester County and Southern NH by mid-morning. Those areas will likely see 1-3" of snow with the higher elevations picking up a little more. Much of Northern NH will see all snow and could receive as much as a foot of fresh snow just in time for the three day weekend! From 128 to 495 a trace to an inch or so is likely at the start...not a lot but because of the timing, there could be some slick spots early on in the commute.
This is a fast moving system and while the warmth eventually wins out, it may not happen until the event is over for parts of Worcester County and Southern NH. In those areas, not only will there be a layer of snow but a coating of sleet or more likely a glaze of ice will be seen as well.
The storm winds down close to midday or early afternoon and in its wake, an upper level disturbance will fire off some snow showers or rain showers on Friday. They will usher in some very cold air for the upcoming weekend with many towns staying in the upper 20s for highs. The weekend however will be mainly clear.
