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Tuesday, January 9, 2007

MLK Weekend or not, January to make a comeback

With winter gradually re-establishing itself across many parts of the country our hope is to quickly build off accumulations of new snow and avoid any additional warm-ups. The big pitfall as we have discussed is the potential ice situation and subsequent warm-up on MLK weekend. This outcome can still avoided but I am increasingly concerned. I am not pessimistic about the period following the holiday weekend which will mark the beginning of what I think will be a big finish to the month. The key feature is the ridge which has recently developed over the northeast corner of the Pacific Ocean and is expected to gradually migrate eastward and settle over the Canadian province of British Columbia. It will prove crucial in our effort to establish a pipeline of consistent colder weather across eastern North America. When you combine this with the more active southern branch of the Jet Stream this year, we will get the opportunity for a late January comeback.

New snow through Wednesday
Periodic bursts of snow over the high terrain will continue through Wednesday largely due to lingering instability across the northeast. There is stronger impulse rotating through the newly formed trough but this system, as mentioned in the last post, will pass south of the region taking the best dynamics with it. We can rely on the fact that temperatures have remained above normal in spite of the trough thereby increasing the low level instability which should in turn encourage the development of snow showers. Also, winds will turn from west to northwest tonight which is a more favorable trajectory for new snow at MRG since it comes from Lake Champlain as opposed to straight off the Adirdondack Mountains. Overall, another 3-6 inches by late Wednesday is a perfectly reasonable best guess.

MLK Weekend
Temperatures will again climb above freezing during the day Friday but the warm-up will be temporarily thwarted Saturday by clouds and a push of low level cold which should keep most of the north country below freezing for the first part of the weekend. It is here where models duke it out over what follows for Sunday and Monday.

1) The American version of events
The american model would suggest that much of the warm weather and much of the rain stays away from northern New England; instead, the low level push of cold Saturday would set the stage for a period of snow mixed with some sleet on Sunday. This precipitation would gradually change to a mixture of sleet and freezing rain Sunday evening before ending as above freezing temperatures assume control on Monday. This is certainly less than ideal but this scenario allows for a net gain of snow/sleet at MRG followed by much colder weather on Tuesday, January 16th.

2) European version of events.
The Europeaon model suggests that the low level push of cold is not as potent on Saturday. In addition. The storm, according to the European, tracks farther north into Quebec leaving much of northern Vermont in a precarious situtation Sunday night and Monday. This solution essentially means that an initial period of sleet and freezing rain (with minimal snow) would change to plain rain Sunday night before much milder temperatures take command for a day on Monday. The european also allows for the change to colder weather on Tuesday.

3) My thoughts
The American model, as inviting as it looks, isn't a solution I am inclined to believe. The model has a southern bias when tracking surface systems and thus the European usually outperms the American model in the 3-6 day time frame. In addition you have other factors that don't work the American model's favor such as the Great Lakes which are anomalously warm (for this time of year) and snow cover which is anomalously absent or very low. My guess right now is that Saturday's temps are in the high 20's or low 30's but its dry, Sunday's temps are near freezing with sleet and freezing rain and Monday is mild with a few showers. This is not set in stone so please root for me to be dead wrong.

Rest of January
In spite of whatever happens this weekend, I am very encouraged as to how things look for the latter half of the month. The teleconnection indices are neutral but features embedded within the jet stream will be positioned in a way which should allow for a consistent stream of colder weather as I mentioned in the opening paragraph. I also refuse to believe that the southern branch is neutralized as some of the models would have us believe. I will instead go out on a limb and predict a significant snowfall either during or just before the weekend of the 20th and 21st of January. Furthermore there are indications that the aforementioned ridge in the Jet Stream will remain in place somewhere in western Canada through a good part of the duration of the month thus setting the table for a comeback of sorts. The pattern may prove to fall short of perfect but in a relative sense it is very welcome.

A quick summary
Warm weather to what is perhaps its final January push into the region Monday following some ice but mother nature should be full of much more positive news thereafter.

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