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Tuesday, February 17, 2015

Two nice doses of snowfall over the next 5 days and (in case you forgot) more ferocious cold

February 2015 will be remembered for its snowfall but also for the unrelenting cold which has persisted in remarkable fashion since late last month. When all is said and done, the month will go down as one of the coldest February's on record for Vermont and one of the coldest months relative to normal in recorded history. Just incredible stuff.

We have more snow to talk about also. We missed the bulk of the post-President's Day weather system. Most of that snow fell over the Mid Atlantic states and most of it did not fall over southern New England, giving those guys a needed break. The pattern is ready to undergo another in a long series of jet amplifications. This is yet another product of the super positive Pacific Decadal Oscillation. The "+2" index will be etched firmly in my memory as one of the biggest drivers of the persistent cold this year. The polar jet energy responsible for the upcoming "jet digging" will be dynamic enough to allow for an outbreak of light snowfall very late in the day on Wednesday into Thursday. Most of the snow will fall after the ski day Wednesday but enough to make Thursday powdery with 4-8 inches of snow between Wednesday evening and Thursday evening. Another major blast of cold, makes a grand entrance Thursday night and this will ensure that Friday is yet another "mostly sub-zero day" on the mountain. Friday should feature some sunshine after morning show showers or flurries. Wind chills will be 30 below zero in the morning but winds will subside by later in the day and the late February sunshine will make it feel a bit more tolerable.

Temperatures will moderate for the upcoming weekend and snowfall is likely as a system cuts from the Southern Plains up through Pennsylvania. The track of this system will force some of the most intense cold out of New England and will also bring overrunning moisture capable of producing several inches of snow later Saturday into Sunday. The eventual nature of this system remains a question mark. In spite of some available moisture, models fail to develop this system into anything of significance and the snowfall would thus be in the "garden variety" category of 4-8 inches. I would not be surprised if expectations change and we are dealing with a more mature storm. We don't want this system to go crazy in the Southern Plains, track to the eastern Great Lakes and flood layers of the New England atmosphere with mild air but I certainly wouldn't mind a 10-plus inch storm. It's a classic New England weather "catch 22". I would have to say, at least as of now, that things look relatively good for at least a light snowfall this weekend.

The jet stream will then re-amplify and ultimately get forced south yet again in the wake of the weekend weather system. This means more cold air and a couple of mainly dry days early next week. During the middle of the week, there is a very good chance for a clipper system followed by what I think will be one more serious blast of cold. We discussed in the previous post about a possible change in the weather pattern around the turn of the month. This still appears very possible as ensembles indicate some serious re-aligning. The biggest change will occur across the Pacific Ocean as the position of the large ridge in the jet stream will shift from western North America to the open waters of the eastern Pacific Ocean. This will make weather conditions more variable for a time in early March although I think a return to the current weather pattern is possible by the middle of the month.

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