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Friday, March 14, 2008

Some snow for the weekend and it gets more interesting next week

The developing block in the North Atlantic Ocean, the catylist for the sinking NAO, appears to be doing its job. Our weekend storm will get deflected to the south thus eliminating the chance for a prolonged period of rain or ice. Instead, the snowflakes should be flying through the early morning Saturday and should leave us with a few inches by first tracks time (3-6 for a storm total). Now we are not working with much when it comes to the cold air. Temperatures will be within a few degrees of freezing through Friday night and into Saturday and this means the snow will be of the more wet variety, particularly at the low elevations. The various pieces of this storm (and there are a few) will fail to align themselves until the system is well off the New England coast. This means that a big event is not likely for any of the Vermont ski areas. That being said, the storms upper air support will swing though Vermont on Sunday and should act to enhance the TIS activity. Sunday will also be blustery and colder and should allow for accumulations to be more powdery in character. It doesn't appear as if any of this snow sunday will be available for first tracks time but its hard to say for sure.

The snow on Sunday will continue into Sunday night and with the help of strong winds, should allow for at least a minimal amount of untracked powder Monday. The winds will subside by Tuesday and the cold will also modify but the questions and uncertainty begin to mount as we head into later Tuesday and the middle part of the week.

Mid-week storm or a crap-out
There is agreemeent next week on a split flow situation in the jet stream and by the end of the week, the formation of a large eastern U.S. trough along with a widespread area of below normal temperatures. The disagreement involves the handling of a very strong feature in the southern branch of the jet stream and it particularly relates to the speeed of this feature. If it successfully speeds into Texas by late on Tuesday then a phase with a developing trough is likely and would thus mean a big mid-week event MRG and surroundings. If this critical southern branch feature lolli-gags in the southwest then the pieces won't fit. Either I think some snow is likely with a powder day later in the week. The "big event" scenario would actually include some rain or mixed precipitation at the onset with a change-over to snow. What is particularly encouraging is that the NAO-block would force any storm to linger in the Canadian Maritimes and allow for a longer period of TIS activity. What is discouraging is that the American Model seems convinced on the big event while the European says "no dice". The European has the better track record in the 5-7 day forecast period but every dog has its day and nothing in the prognostication game is ever certain.

Long Range Notes
The period from the 20th to the 25th which includes a weekend will be a cold one relative to normal thanks largely to our NAO teleconnection. The eastern trough will in fact be large enough to allow cold air to envelop quite a large area of the eastern United States and eliminate the southern branch as a producer of storms. Precipitation which may be somewhat limited but will fall as all snow in this period and will fall as a result of clipper systems and other TIS enhancers. Winter is certainly not over and next weekend will prove it.

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