Think Snow, Tweet Snow !!!

Sunday, December 6, 2009

Hopes for epic powder on Wednesday fade but favorable pattern remains

And although it would seem as if we have made it through a long stretch of unseasonably mild weather we have yet in fact to reach categorical below normal temperatures and may not really do so until later this week. It is however cold enough so that the little that did fall Saturday will remain in place as the next very closely watched system approaches late Tuesday. This system has potential but its track has become problematic and each run of the very trusted European model seems to confirm that our prospects for big powder from this storm are fading. This system can still do a lot of good as far as priming the base for future events.

The system in question is poised to clobber the interior west from the Sierra Nevada mountains to the continental divide in Colorado. It will then tap into moisture from the Gulf and move northeastward. It should prove to be quite an event for portions of the Upper Midwest but its track as it continues to push toward New England will allow warm air to invade critical layers of the atmosphere. This movie has been played out before many times and often warmth from the Atlantic can get pinched off as energy gets transferred to the coast. I expect this to happen to a degree but the event will nonetheless consist of snow to start followed by a change to sleet before ending as a few days of terrain induced powder late this week. I think the uncertainty at this point revolves around precipitation type and the particulars regarding how much snow verses sleet verses freezing rain verses dare I say rain. Sleet would be the ideal primer and we should receive a healthy dose of that Wednesday but hopefully we can keep the freezing rain and rain out. The European model would suggest that this could be a challenge while the American model says sleet will likely be the primary precipitation type Wednesday. I would say around 5 inches of snow and sleet is a good initial guess on this event. Remember however that sleet is exponentially more dense than snow and that a few inches of sleet has tremendous staying power were it to fall. With powder seemingly becoming more far fetched I am pulling for a "sleety" outcome as it will be this which will get MRG open the quickest in my opinion.

Much colder temperatures will advance into Vermont Thursday in the wake of this storm and preliminary indications suggest two days of a cold and not entirely dry westerly fetch of air. Such a setup should provide a shallow layer of instability and terrain induced snow leading up to the weekend. More details on that later in the week.

I am becoming more impressed with the "sustaining" power of our new high latitude blocking pattern. It may have started with the "Omega Block" across Alaska but will evolve over time into a combined negative AO-NAO fueled jet stream configuration. This should be one where the jet stream is forced southward and where rain events and even thaws will be tough to come by. I am going out on a limb here and will suggest that all precipitation after Wednesday's event and up into the time of Christmas will be snow. Hopefully we won't let the opportunity to build an early season base pass us by. My guess is that we will not and should go into late December with my kind of holiday cheer !!!

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