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Wednesday, April 17, 2013

An improved 2012-2013 season with a happier ending

A season wrap-up was promised and has not been delivered until now. All I can do is blame it on tax time which is only somewhat true. Winter continues to only slowly relinquish its grip on New England. The elevations across the Green and White mountains still have lots of snow and I know for some, ski season has yet to reach a conclusion. From a behavioral perspective, the weather has changed its mood since the beginning of the season and certainly since last year. For the time being, vast expanses of above normal temperatures are not the glaring characteristic of the weather pattern and we are instead seeing areas of the country that are seeing extended stretches of below normal temperatures. On the agricultural front, rain and snow in the north-central part of the country have made and will continue to make a healthy dent in water deficits and hopefully end a drought that in some areas got rather severe. Across New England, the end of the winter was somewhat unremarkable relative to normal but much colder than 2012 giving many the impression that it has been quite chilly but actually its been quite normal. 

In the end, the winter 2012-2013 will not be particularly distinctive good or bad and will likely be remembered ambivalently if at all in a few years time. There were many improvements from 2011-2012 mainly in the form of more consistent chill and longer stretches good skiing. Still, many of the better stretches of the winter were interrupted violently by short yet very damaging thaws that left the mountain begging for powder. By the middle part of February, Mad River and much of northern Vermont saw some decent skiing which was started by the epic noreaster responsible for the over 2 feet of snow in Boston. The fun continued through a good part of March, interrupted only once by some rain on the 11th of the month. There were times, even when the pattern was favorable, that the Green Mountains seemed to be on the short end of the stick either by missing storms or striking out in many of the instances where terrain induced snow seemed likely. A few storms and to some degree, the big February noreaster delivered much of their snow to more southern locations. If it was not for the thaws, the misses and glancing blows might have gone more unnoticed but at times we did seem to struggle when we needed the powder the most. 

Meteorologically, the winter was anchored by a mixed bag of features in the jet stream some of which supported snow and cold while some did not. The SCWB coined the "Favorability Index" a few years ago to try and better quantify the outlook strictly from the standpoint of "teleconnections". The most important of these teleconnection indices, the Arctic Oscillation (AO) was negative for much of the winter and significantly negative in March largely contributing to the generally positive favorability index. The North Atlantic Oscillation (NAO) was also negative to a lesser degree and helped provide support for sustained periods of colder weather in eastern North America. In the Pacific however we saw many of the same behavioral characteristics as we did during the prior winter. The jet in the Pacific, particularly early in the winter often tightened fueled by an expansive ridge in the eastern Pacific and a trough over Alaska. Seeing the eastern Pacific ridge was in fact so exasperating, that we nicknamed the feature "the evil empire" for its propensity to completely disrupt good skiing in Vermont. The disruptions were quite evident in the thaws that crippled the mountain on more than one occasion. The worst and most depressing thaw occurred before the mountain was even close to opening in early December. Other more short-lived thaws occurred in the middle and at the end of January. The January thaws were bracketed by some very cold weather and very little snow. 

Throughout the winter, there were periods of active and inactive weather. The big turning point in December was seeing the MJO finally cycle and allow the ridge in the eastern Pacific to at least get temporarily broken down. The result was some active weather and even some split flow in the jet stream. Some rather intense storms in December were able to move through the Rocky Mountains and impact New England. The first few of these over-amplified in the Midwest largely scouring any cold out of Vermont. Still, the high elevations were able to get some decent snows and the mountains were finally establishing a workable base. Then on December 26th, the right combination of jet energy and cold weather produced the best storm of the year for MRG. Over 20 inches fell out of that and some additional snows combined with enough cold weather allowed that good skiing to persist through January 10th. Another active stretch of weather occurred in the later part of February with some similar results. A few storms were guilty of an early maturation and thus did not give the mountain their best shot but a few also brought some good powder. The season then concluded nicely with a post St Patrick's Day dump that left the mountain powdery for days. 

With that, it is time to sign off for the year and enjoy a well-earned period of warmer temperatures maybe some backyard BBQ if your into that. It was another fun year blogging for the passionate skiing and weather enthusiasts that make up this very close knit community at Mad River Glen. For all of you non-MRG skiers and snowboarders, even you Sugarbush and Killington folk, we are happy to have you here also so long as you play nice, but consider joining us on the mountain at MRG next year and supporting the skiing cooperative. Enjoy the summer everyone and we will talk again late in the fall.