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Monday, December 26, 2011

Variable upcoming week but a better outlook after Jan 2

We did get a few days where it did truly feel like winter and the outlook appears more wintry going forward but the next week or so will be very hit and miss. The big weather system Tuesday is a big miss. The phasing of southern stream moisture and polar jet energy will not bring us much as cold weather is simply incapable of holding its ground in this pattern. The system will bring its precipitation to the region Tuesday evening as a mixture of rain, snow and sleet but ultimately the mountain will get another several hours of rain. The system will indeed bomb out as it approaches the Canadian Maritimes and this will help usher cold back into Vermont early Wednesday accompanied by some snow but we could've used a better result from this and we simply won't get it. Overall it looks like about an inch of liquid will fall from this system with 70-80 percent of it rain and 20-30 percent snow Wednesday thus about 3-4 inches.

From Wednesday onward the outlook is more optimistic and significantly snow after the New Year. A series of clipper systems between Thursday and New Years Eve will yield some fruitful results. Products of the very intense Polar/Pacific jet stream, the first of such systems should arrive later Thursday and spread a light accumulation of snow to most of Vermont and New Hampshire and a second could spread additional snows to the region Friday night into Saturday. Put together, the accumulations from these two systems could total as much as 10 inches. The snowfall will be very fluffy in nature and the 10 inches is the optimistic side of the range but we will take that in what has been a very tough month. The now frozen Hudson Bay is also finally lending a hand since it appears some cold in eastern Canada is finally showing signs of fighting its way into the region since it can't seem to make any progress anywhere else in the U.S. right now.

The warm-up promised for New Years Day (plus or minus a day or two) is still evident on the forecast weather maps but not quite as intense in magnitude or duration. It will begin with a warmer, above freezing afternoon on New Years Day and will hopefully end with a minimal amount of rain on the 2nd. Maybe the trend toward removing this from the forecast picture will continue but for now I would continue to expect it.

The better news involves manifestations upstream of the region after the New Year. The Pacific has, as mentioned many times, been very problematic so far this winter season with the upper ridging in the Mid-latitude regions clashing with a polar vortex over Alaska for much of the month. At around the time of the New Year, the jet energy across Alaska will at least temporarily win this clash and allow a deeper trough to form in the eastern Pacific and consequently a ridge to develop in western North America. The upper ridge now appears as if it may be one of the stronger features on the Northern Hemisphere weather map in about a week or so. This type of pattern is much more amplified and should allow for a period of much colder and wintry weather across a broad area of the eastern United States after the 2nd. It does not mark a switch in some of the major teleconnection indices that we track but we should a neutralization of these indices and hopefully - game on.

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