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Monday, December 15, 2014

Evolving weather pattern will bring back the cold while storm potential continues

Though it may be categorically "above-normal", a thaw it has not been. Temperatures have generally remained below-freezing on the mountain and the deep snow has so far held its ground. The next storm system will bring its precipitation to the mountain Tuesday night and we still expect temperatures in the lowest 5,000 feet to be very marginal. This being said, models are only allowing these "marginal" temps to get to about 34 or 35 which keep the door open for mixed precipitation as opposed to plain rain. The summits might be able to keep the precip-type completely frozen. This system is eying the St Lawrence Valley as it's favored track but it will make that important jump to the coast during the day Wednesday and in doing so will allow the lower troposphere to cool enough to support some snow. What does fall later Wednesday into Wednesday night will be of the terrain-enhanced variety and could accumulate 2-5 inches by first tracks time Thursday.

There is lots to talk about today including some potential storms and some big-picture changes that will have a profound impact on MRG weather as we head toward the end of 2014. In spite of all the snow, the pattern has not been anchored by favorable teleconnection indices and the jet stream in the Pacific has been much too tight for my liking allowing the EPO index to remain positive. Over the next 7-10 days, the jet in the Pacific will loosen dramatically, a ridge will establish itself over Alaska and the Polar jet will make it's presence known. The country as a whole has seen very limited amounts of cold over the first two weeks of December and MRG has had a very limited supply to work with during the last two recent snow events (though we managed to come out on top anyway). After Christmas, this will be very different, cold will cover much of the country, New England included, and so long we can keep the southern branch of the jet stream active (which is legit question), things will get very interesting.

Actually things are already interesting and this refers back to our last discussion a few days ago. There are two systems of note and one or both or none could have a significant impact on the region between the 21st and 26th of the month. The first is a strong southern branch system, yet another in this El Nino winter, which will progress across part of the country by the 20th and then attempt to make a northeastward turn as it heads toward the Atlantic Coast. Models over the last three days have produced a variety of results regarding the outcome of this system. As of Monday afternoon, the consensus of information actually allowed the storm to simply move out over the ocean and remain a non-event for most of New England. I bring it up however because it is hardly game-over with this system. The polar jet will remain rather uninvolved in the weather pattern through the 21st and thus the door is open for this thing to make critical northward turn. I wouldn't at all be surprised to see models sing a different tune on this storm either tomorrow or the next day.

Potential storm #2 will impact the region around Christmas as cold air invades a large swath of the plains and Rocky Mountains. There is legitimate concern that the pattern could initially amplify too far west and allow any storm to ride into the Great Lakes but it's early and their are lots of moving parts here. Incoming polar jet, southern stream energy and changes in the pattern at a big picture are level are all going to have some impact.


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