Monday, December 20, 2021

Even as milder weather controls much of the eastern United States this Christmas, winter maintains a grip on Vermont with several chances for light snow in the coming week

A couple runs of the European Model was suggesting a widespread torch on Christmas Eve and Christmas Day over portions of the Plains, Midwest and Southeast. On the heels of the out of season weather last week and last years Christmas monsoon, this caused a bit of a stir in the social media weather back and forth. Though the weather has trended in the "not as cold" direction over Vermont, our outlook still appears pretty solid for winter weather through the holidays. Our biggest concern involves the track of a  potential weather system on December 28th, but taken at face value, sub freezing temperatures appear likely to hold their ground, especially above 2000, where most of us actually ski. 

A clipper system, well to our north will give us a distant hand wave but aside from some flurries or very light snow, we won't see much of anything. If you're desperately looking for that 1-3" then head toward the Canadian border but most of Vermont will just see intervals of clouds and sun on Tuesday with temperatures generally in the 20's. We have better chance of snow early on Wednesday when a strong sub-tropical system off the Atlantic coast begins to team with a stronger polar/pacific impulse. An area of snow will be expanding across eastern New York and interior New England and although the best area of snow clearly appears to be Maine, several hours of light snow is likely across the northern Vermont high country before dawn or at least before the ski day Wednesday. This appears to be a 1-3 situation but additional changes are possible. 

The cold weather will hold its ground across Vermont on Christmas Eve/Day but the milder air will make a big push northward and that process will create a zone of moisture and precipitation across the northeast. In Vermont most of that will fall as snow, so long as the moisture makes it far enough northward before decaying as it runs into dry airmass stationed to our north. The timing of all this appears to be either late on Christmas Eve or early Christmas Day and would amount to another light accumulation for the Christmas ski day if it happens. 

The big picture outlook has trended toward the less cold side. The main reason for this has to do with the bitterly cold air having a specific focus on western North America particularly western Canada. Meanwhile, a blocking ridge will migrate from central Greenland to the Hudson Strait well north of us. Oddly enough (or not so oddly), this pattern appears similar to the jet stream configuration that prevailed in the weeks following Christmas last year. Though much of the Vermont high country remained sub freezing throughout the period and even scored some decent snowfall, temperatures were not bitterly cold and continued to average above normal relative to climatology. 

As mentioned in the opening, there is evidence of another organized storm impacting our region around the 28th. We have what appears to be a soft area of cold weather dominating much of interior New England and eastern Canada around this time and although in the case of Vermont, milder air will make another run at the region, ensembles are suggesting that sub-freezing temperatures hold. This means that the forecast for the holiday week should consist of temperatures in the 20's and 30's for highs and mostly teens for lows. Chances for snow or wintry precipitation are on the aforementioned Tuesday the 28th and again closer to New Years.

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