Tuesday, December 12, 2017

Got one in the bag, more is on the way but lots of uncertainty in the outlook going forward

Our first significant snow has successfully blanketed the region Tuesday and more is on the way. We should expect to see additional snowfall through a good party of Wednesday along with blustery conditions and temperatures generally in the teens but it does not appear to be the greatest case for terrain/lake snow at MRG. There's only a shallow layer of low level instability over northern Vermont Wednesday and some wind shear above this unstable layer. That said there is plenty of lingering moisture. 2-5 inches Wednesday on top of the 10-14 Tuesday and Tuesday night should bring storm totals to a foot or more though snow conditions at the summits will be pretty wind blown thanks to strong northwest winds.

A series of small weather systems will keep most of the snow action to the south Thursday and Friday. Temperatures will be quite cold and possibly find their way below zero for the first time this winter season on Friday morning. Readings will only rise into the teens both Thursday and Friday. Temperatures will moderate on Saturday, opening day, and some snowfall will return from a rather benign looking weather feature. A few inches is certainly possible on Saturday.

Uncertainty rises rather quickly after Saturday. Models are having a difficult time wading through the specifics of a pattern that is expected to relax Sunday/Monday and then re amplify Tuesday and Wednesday. There are varying scenarios being advertised and for now I prefer what appears to be the colder one. Dry arctic air will re establish control of Vermont's weather Sunday ahead of a mild push of air and a weather system Monday. Snow or a snow to ice situation should accompany this milder push of air which and its yet to be determined how substantial this precipitation event might be. Colder air then re establishes control of the regions weather Tuesday into Wednesday and some terrain/lake induced snow is possible as this happens.

Ensembles continue to go back and forth for Christmas week. This is turning out to be a very difficult forecast. Conditions in the Pacific will flirt with adversity in the middle of next week but the EPO is expected to slide back into negative territory as mentioned in the last update. A loose jet (negative EPO) in the Pacific is a very critical component in keeping arctic air a part of the weather picture across New England and many other places. In addition, a nice looking Omega blocking feature in the jet stream is still the expectation across Alaska. The position of this feature is very critical. If it sets up shop too far wet across the Alaskan Peninsula it could invite a push of warmth along the east coast. If block is positioned along the Alaskan/Canadian border, Vermont will be very wintry, cold and possibly snowy. I think Vermont has a good chance to be on the wintry side of the action but I'll admit it's a little closer than I would like it be.

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