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Thursday, February 19, 2015

Light snow for the weekend, more cold for next week along with some midweek snowfall

Our stretch of sub-freezing temperatures has now extended beyond a month and the snow continues to fall even if not in the largest of doses. Light snow will become mostly flurries Friday along with blustery winds and mostly sub-zero temperatures. The bitter chill continues through early Saturday but temperatures will moderate during the day as any sunshine gives way to clouds in advance of our next snow producer.

This next weekend system appears discombobulated today and though it will keep our potential snow on the lower end, it also nullifies the risk of any mixed precipitation or ice which is something we certainly do not want at this stage in the game. The storm, if you want to call it that, will track up through the Ohio Valley and bring with it a disorganized area of moisture along with it Saturday. The frontogenetics (yeah a big word but I lack a better one) do not support any heavy precipitation up our way but snow will begin Saturday evening and continue off and on into Sunday Morning. I would put accumulations in the 3-5 inch range at this time so certainly enough for a mini-powder day. Most of Sunday will feature flurries along with temperatures in the 20's, which should feel quite balmy no matter what part of the Northeast you are coming from.

More cold dry air envelopes the region Monday, again sending temperatures below zero and perhaps back to -15 by Tuesday morning.  The weather pattern then gears up for another major amplification. It will be the last of such an occurrence for the very distinguished month of  February 2015 and perhaps the last in this very memorable weather pattern. There are hints that a significant storm could be one of the byproducts of all this during the middle of the week but the end result will depend heavily on the amount of available subtropical or southern branch moisture. Models have produced some differing results on this question though we have managed to perform quite admirably even without much involvement from the southern branch of the jet stream. This is surprising since typically it is a characteristic that is more pronounced in any kind of El Nino, even a weak one. I'll take snow anyway I can get it, but we will get potentially a big snow with the help of more subtropical action. Without it, polar jet energy could still bring more garden variety type snows before the next wave of cold overspreads the region late into the weekend through the end of February.

I have been watching the early part of March quite intently since it still appears as if the jet stream configuration will do some major realigning. The super positive PNA jet structure will disintegrate and a large western North American upper ridge will shift into the eastern Pacific Ocean. There are obviously changes that are about the occur simply due to seasonality but the added effects of the shifting weather pattern will certainly result in some very different results for Vermont going into March. Interestingly, the last few cycles of ensemble runs have shifted markedly away from any prolonged thaw and even suggest a continuation of below normal temperatures into early March even if the intensity of the cold is far less than it has been. If we could move into such a regime, it could mean a very interesting start to March. The polar jet would recede, we would see a major warm-up across much of the southern United States while a much more active jet stream brings several storms across the country. Yes, we could get unlucky and get a round of mixed precipitation or rain out of one of these but we could also score a major snowfall. In fact, I think the latter is more likely.

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