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Wednesday, January 14, 2009

Cold subsides by the end of MLK but snowfall is a question

No blog update for a few days either means that I have been busy or I am sour grapes either because the Giants have just lost to the hated Eagles in the playoffs or I missed a forecast. The latter was a bit frustrating because I had it on these other guys all week by talking up the idea of snow only to fade the idea within hours of the event. Oh well, we are now in the firm grip of some bone-chilling cold which will only intensify over the next 24-48 hours. My hats off to those brave souls who I can see by the Mad River single chair web cam are braving the elements.

Mainly dry through at least Saturday
Some of the bigger metropolitan areas will pick up a few inches of snow Thursday morning as a clipper system travels rapidly east on the wings of the polar jet. This is a suppressed jet as of now and we will miss out on the little available moisture there is with this system. We will instead have to settle for continued cold through Friday with temperatures approaching -20 in the morning and struggling to reach zero during the afternoons. The weekend will also feature some brutally cold mornings but the afternoons will be a bit more forgiving as temperatures climb well above zero. The wind this weekend will also subside somewhat alleviating some of the impact of this latest cold wave on Saturday and Sunday.

Manitoba's weather system
We do have a weather system to watch this weekend and a significant one at that. In addition its another weather event where major model disagreement is making it difficult for us prognosticators. And just like last week, the European model is suggesting a major snowfall while the American and Canadian models have backed away and are keeping most of the big moisture off the eastern seaboard. There is not a lot of room to play with. The eastern trough responsible for the cold will remain in place through the weekend but its width will collapse and it will have a very sharp but narrow look by early next week. Within this long wave structure comes the "Manitoba Mauler" with some rather impressive upper level vitality but with little moisture. If this system has a constructive impact with the Atlantic Ocean it could evolve into a major snow event for parts of New England. It could however do all its damage off the coast and be quickly written off as another "almost". It is important to note that moisture from this system is unlikely to make its way to the Green Mountain chain until late in the day Sunday. This leaves the door open for a big time powder day on MLK day but nothing much prior to that.

Beyond MLK...
In the wake of our MLK system will be some garden variety chill but we will see a moderation in temperatures as the week progresses. This happens as the strong western ridge migrates westward from British Columbia while at the same time blocking at the poles (as measured by the AO) index is at a minimum. This temperature moderation will be very short-lived in my opinion because the high latitude blocking which will be lacking next week will quickly re-intensify and the global long wave pattern will support a resurgent area of cold covering a broad area of North America. The warm-up next week could make room for a weather event that is briefly non-snow around the 24th. If we can avoid that however the coast will be clear for the duration of the month and the door will be open for additional natural snows in the last few days of January.

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