Think Snow, Tweet Snow !!!

Tuesday, December 18, 2007

Clipper me this ! At least 5-10 more inches of powder for Thursday first tracks

No, those innocent moisture-starved clipper systems are certain short on drama but they do consistently deliver. Powder that is, particularly to the high terrain of Vermont and is what this one will do. This is a system we able to key on fairly early in the ball game but up until now it was a bit uncertain as to which day would feature the most new powder to ski in. The answer is Thursday. Snow from this vigorous upper air disturbance will approach from the northwest and begin falling late in the ski day Wednesday. MRG should see snow much of the night and into Thursday morning and accumulations will be enhanced by the effects of the local oragraphy. Do you want my advice ? Take the day off Thursday and get your rear end to MRG and enjoy the last days of this favorable pattern. 5-10 inches of snow from this clipper atop the already fallen December snow will make Thursday one of the best December ski days at Mad River since 2002.

La Nina is hunting is down


Now I am well aware of our good fortune so far this December. The winter of '07-'08 has begun much the way '06-'07 ended. I am also well aware of my seasonal prediction and I can say one thing regarding that. I am not changing it - The forecast must be judged on its content prior to the season and I will happily taste crow should the prediction go up in a plume of smoke. La Nina, by the way, has maintained its moderate strength and is quite articulate in its speakings to the current weather pattern. The biggest feature across the Western Hemisphere is a large upper air trough in the Gulf of Alaska with a ridge directly underneath it northeast of Hawaii. The two features when put together create a powerful jet which will work quite efficiently at ridding mid-latitude North America of its arctic air. New England, in fact, will be one of the last places in the U.S. to be encompassed by cold weather as early as this Friday. Looking for a silver lining ? I can give you the following. Teleconnection indices are not overwhelmingly unfavorable at face value. The AO is forecast to run Neutral, the NAO is indicated to even go negative (favorable) leaving the PNA as the only major teleconnection index to be consistently working against us (it will be running negative). Translation - We could dodge a few bullets but there will be numerous of them around to avoid.

The Sunday Dilemma

The first effects of this adverse shift in the global pattern will be a bullet that will prove very difficult to avoid. On Sunday the arctic cold will move off the Atlantic Coast and in doing so become quite stale. As this is happening a low pressure center will take dead aim on the St. Lawrence valley and push warm air deep into the northeast U.S. and even into southeast Canada. The result on Sunday will be freezing rain which will develop during the day Sunday and ultimately go to plain rain for a period of time Sunday night. I do not believe temperatures will get especially warm during this event and thus the deep early season base will see little depletion. With freezing rain or rain however comes the crust once a re-freezing occurs and I believe this happens quickly on Christmas Eve as colder air arrives in the wake of the storm. This colder air combined with marginally favorable dynamics may be enough to induce some TIS (Terrain Induced Snow) into X-Mas day but its too early talk accumulations. It is possible that we could see some however and this could bring some serious help to Christmas Day skiing.

X-Mas to New Years

During the last week of December, much of the country will be be covered by Pacific Air and it is my thinking that much of New England will see above average temperatures in spite of any brief intrusion of colder air on December 24th - December 26th. The models are going off on some expected tangents in this time frame with the American GFS model showing a more amplified pattern consisting of a more amplified negative NAO. The results of such a regime would be temperatures which are closer to normal and some new snow. The European however suggests much more in the way of milder weather and much more in the way of rain. All of the ensemble data confirms that it will be a very difficult pattern for us to navigate through with several potential land mines going into early January.

3 comments:

John said...

Josh,
I am new to your blog and sincerely appreciate what you are doing. As a recent transplant from Minnesota to Watertown, NY, I miss a similar blog by Mark Seely, a professor at the University of Minnesota, who discussed weather weekly. Your approach, while different, fills a void. Thank you.

Pls. take a peek at what mark does:

http://climate.umn.edu/cawap/mpr/mpr.asp

johnfparker said...

Josh, I am jonesing for your next update. Why don't you quit your day job? Thanks for making all my days at the rock pile more bearable...

johnfparker said...
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