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Friday, January 5, 2007

The Fight for MLK Weekend

With the first weekend in January overrun with mild weather and rain all eyes now shift to the weekend of the 13th-15th in search of hope. The weekend honoring the great civil rights leader often marks the commencement of Mad River Glen's peak, when the base becomes deep enough to support many off-the-groomer adventures. It is safe to say that we have somewhat lowered our expectations this year; nonetheless, with arctic cold invading North America next week, the opportunity at redemption has presented itself. Whether or not the opportunity is seized remains a big debate.

The first taste of a new beginning Sunday Night
The rain and the near-record warmth needs no further additional review. The move to colder temperatures, which will be a step-down process, begins Saturday night and the 30-degree above normal temps are replaced by readings closer to 15-above normal Sunday. The first forecast challenge then arrives for Sunday Night in the form of a developing weather system that will be moving northeast up the coast along the tail-end of the already-passed cold front. Temperatures by this time will be very marginal, but models have come to a consensus that moisture from this system will indeed reach Mad River Valley and beyond and should provide an opportunity for a few inches of wet snow.

Powder early next week
Whatever does fall Sunday night into early Monday will be the start of what should be a far more intriguing period of weather across New England. During the day on Monday, colder temperatures (categorically normal), make a push into New England but as this happens, the lower troposphere will remain unstable and will thus start the Stark Mountain induced snow machine. The snow showers which should begin during the day Monday and last through Monday night are certainly be capable of producing 3 or 4 inches but this precedes a very potent upper air impulse which arrives on the wings of the Polar Jet on Tuesday. Some of the models are actually suggesting that Tuesday's system may develop into a coastal snow producer for Maine. For most of the Green Mountains, the system should bring much needed snowfall, particularly to the high elevations. I don't want to get caught being too specific but the mountains of north central Vermont could easily see anywhere between 1-2 feet of new snow in the period beginning late Sunday and ending early Wednesday.

The MLK Weekend conundrum
The headaches begin as we push toward MLK weekend. I am a big fan of looking at the "hemispherics" of a pattern which is more or less analogous to simply saying I try to look at the big picture. I mentioned in previous posts that the catalyst for the arrival of arctic air is the ridge which will develop across the northern latitude Pacific Ocean and extending up 155 W poleward across Alaska and beyond. Its an important feature and should bring plenty of bitterly cold arctic air into North America. The problem is that this so called "catalyst" is too far west, and will allow the deepest penetration of cold next week to occur in the western United States, not the east coast by late next week. As the cold air plunges into the Rockies, we may very well be watching more news footage of snow in Denver. This presents a problem for us skiers in that any deep upper air trough across the Western U.S. will bring about a ridge in the eastern United States. Its the jet stream more or less acting out Newton's third law of physics.

Best and Worst case possibilies for MLK weekend
The american model is keying on the aforementioned scenario and therefore replaces all of next week's colder temperatures with very mild weather for MLK weekend and an eventual period of rain. This is nothing short of a massacre but it can be avoided and the situation could and might very well turn out a lot more positive. When the American model integrates out past 6-7 days it likes to produce these merdional and very symmetrical scenarios with a trough and very cold weather in one part of the country and a ridge and very mild weather in another. The final outcome often does not turn out that way. In this particular case the trough in the West is not likely to amplify as the American model suggests. Assuming it doesn't, we have to hope that it splits, sending a piece eastward to mitigate the effects of the eastern ridge and keep us within reach of the arctic cold (which will be close in any scenario) and even the overrunning snow. Even the most positive scenario would have a threat of ice but a snow/ice scenario is much better than rain. I would not at all be surprised to see 65-degree temperatures in Philadelphia on MLK weekend while it is simultaneously snowing or icing with 20 degree temperatures at MRG.

Beyond MLK
Beyond the MLK holiday there is reason for more hope. The ridge situated over Alaska is shown to migrate slightly eastward allowing for a continued delivery of arctic cold. The NAO is shown to remain positive which is an adverse factor although even a normal regime is significant improvement over what we have seen. In addition, and as i mentioned in previous posts, if we can combine the presence of arctic air with an active southern branch then we should enjoy the results.

Quick Summary
New snow and colder temperatures early next week should follow the weekend washout but then the fight for MLK weekend begins which could yield both negative and positive possibilities.

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