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Thursday, January 11, 2007

The great MLK day turn-around, GO GO GO

It gives me plenty of satisfaction to report on many exciting things in this update. The most dramatic of which will occur at the tail end of this weekend. For the few that have followed this story in its entirety, we knew that the pattern was changing for the better around this time but the few days embedded within the upcoming holiday weekend looked dicey. I knew that northern New England was quite capable of turning this potentially lousy situation in to something positive, particularly in an El Nino year but the consistency at which we have been thwarted was both alarming and emotionally scarring so far this winter. Speaking of the recent and very remarkable stretch of mild weather, I heard a great interview on NPR's "All Things Considered" yesterday where Robert Siegel asked Penn State (my alma mater) meteorology professor Dr. Michael Mann about the extent to which global warming played in to the mild weather. The question is certainly one that often gets thrown my way but his answer was better then any I have given. He analogized global warming's influence on individual weather patterns to "loading the dice". He said accurately that weather patterns are deterministic and form because of a set of random and chaotic events. The intensity and coverage of the mild weather this year was like rolling "snake eyes" although global warming can make snake eyes a bit more likely than it would be under normal circumstances. You might be able to find the interview on NPR.org but I thought it was worth mentioning.

The MLK weekend set-up
Rolling "snake eyes" has given us our 5 weeks of skiing infamy but we have rolled again and come up with a much better outcome so lets get too it. We have expected (or at least I expected) much better things from El Nino and its finally playing the role it was anticipated to play. The eastern upper ridge is in the process of rapidly forming but a southern branch, fueled by El Nino, is going to quickly destroy it before it comes a dominant influence on the weather pattern. In the process of its destruction, a fairly strong low pressure system will move from the southwest to what I think will be the New England coast. It will be a system containing a very broad shield of precipitation and will be a system which will prove to be of great assistance to those of us hoping that MRG can quickly build a skiable base. There are other very important things at play here as well. Arctic air, as discussed, is now on the playing field and the splitting of the trough in the west will allow a push of cold weather to quickly re-assume control Saturday after an afternoon of above freezing temperatures Friday. This sets the stage for the events of late Sunday and Monday (MLK day). Two days where no longer do we expect above-freezing temperatures and where significant additions can be made to the base.

MLK day storm
Sunday itself turns out cloudy but with little precipitation and temperatures will remain below freezing. The storm at that time will prove to make itself known at the Seattle vs Chicago NFC divisional playoff game. Precipitation will make its northern New England arrival Sunday night in the form of snow and will continue either in some form through a good part of Monday. There are disagreements amongst the models concerning the details and I should bring up the fact that the American model now tracks the storm so far south that much of northern Vermont misses the heaviest precipitation although the precipitation type remains all snow throughout the event. When it comes to the track of this storm I am still inclined to go more with the European (which has also shifted its track southward but not as much) model or at least a blend of both. This would mean several inches of snow Sunday night into early Monday followed by a period of sleet or a snow/sleet mixture during the day Monday. Precipitation would end as snow Monday night before it turns windy and much colder Tuesday. The sleet factor makes it very difficult to predict accumulations but 6-12 inches of snow and sleet is a very reasonable first guess. I know also that sleet isn't exactly powder but sleet also makes a very good foundation for a workable base.

New and improved
Winter as we formerly knew it will re-acquaint itself with the region Tuesday and Wednesday bringing below zero (F) temperatures to the region during the overnights and only single numbers during the day. At this point, the new and radically improved pattern will become entrenched and we will watch as the powder continues to fall, and it stays cold. The medium range models suggest that the next two chances for powder come Thursday and then more significantly on the weekend of the 20th and 21st. This assumes of course that the southern branch goes dormant next week which I am not entirely sure about. Even if this moisture-rich portion of the jet does quiet down for a time I doubt it will be that way for long.

The big turn-around, can it be done ?
Lastly I wanted to discuss a more broader view of the weather pattern for the balance of the month and it also is a very encouraging topic of conversation. Although the teleconnection indices are neutral, the new pattern's most dominant feature is a ridge which will oscillate in position between the extreme northeast Pacific Ocean and western Canada. This will be enough to maintain a healthy stream of colder temperatures over the region. The feature is shown to maintain its strength and even intensify over the course of the next two weeks. In addition to this are some of the ongoings in the southern latitudes of the Pacific. Between 10-25 N in the Pacific, the long range ensembles show negative jet stream anomalies. This is in effect an indication of a healthy southern branch but also a weakened or split mid-latitude Pacific Jet. The aforementioned happen to be some very fundamental ingredients to great periods of winter weather gone by such as '92-'93 or '77-78. The '92-'93 winter had many of these things along with a positive NAO similar to that of this year. So in concluding I will say that yes the pattern change could be limited to a few weeks but it could turn out to be one of the most dramatic mid-season turn-arounds in a while.

The Quick Summary
MLK weekend to prove productive before its done and mark what will hopefully be a memorable mid-season turn-around.

2 comments:

ricardo said...

go cat go

Damon said...

I am hoping it does turn around, and thanks for the detailed and scientific long term forecasts, but I find the white on black to be very hard to read.