As of late December, La Nina has strengthened slightly and is currently edging out last year's version by a tenth of a degree C. Measured in terms of weather pattern behavior however, this year's version appears more amplified and has had a very negative impact on winter weather on the east coast, especially from the Mid-Atlantic states southward. The southern Appalachians might as well be a tropical destination this past month as temperatures have hardly been sub-freezing and dewpoints have recently soared to near 60-degrees with accompanying heavy rain and thunderstorms. La Nina has always been a mixed bag in Vermont. Though we typically perform way better than the areas mentioned above, we have also experienced a few clunkers such as 1988-89 and 2011-2012. Though we appear to be heading toward another "clunker", the weather pattern does appear favorable for a half way decent stretch of winter in Vermont through about the first half of January. This is a critical stretch for us since we have some jet stream blocking in the Arctic and have managed to tame the Pacific jet stream for a time. I certainly don't expect these conditions to persist indefinitely this year and we thus need to make something happen and soon.
Not much good will come from our New Year's weekend weather situation but there are worse results than this one. Most of the wet weather from multiple waves of low pressure will pass to our south and New Year's Day will feature just some spotty light rain or drizzle with temperatures hovering just above the freezing mark across much of the northern Vermont high country. A push of colder temperatures will reach the MRV early Sunday as another in a series of low pressure waves passes to our south. Light rain will become freezing rain and sleet for a time and eventually turn to snow sometime during the ski day. 1-3 inches is likely from all this but there continues to be the risk we get screwed entirely.
Portions of the coastal Mid-Atlantic and SE Mass, which have seen little to no winter so far, might receive a bit of snowfall fall from a rapidly strengthening low pressure center off the coast. This is a big whiff for Vermont, but big offshore storms are the best way to get the sun out and visibility improved in Vermont during the winter months and we should see a healthy dose of sunshine to go along with chilly 15-20 degree temperatures. Sunshine will be back for part of Tuesday and will help to warm readings back into the 20's before warm advection clouds advance back into the region. The window for milder potentially above-freezing temperatures appears short and confined mostly to valley locations on Wednesday. Even better is the potential for a big winter storm late Thursday Jan 6th into Friday the 7th. It's a delicate situation involving arctic air spilling south and a rapidly amplifying jet stream. There's also some lingering mild air along the immediate coastline as another potential monkey wrench. Still, the ensembles are showing a nice consensus for a decent event and interior New England appears to be the best location for results. Operational models have and will continue to be noisy for the next few days but more clarity should arrive within a few days. It's the best chance we've had all winter for a decent storm but it remains a "chance" for now and not yet likely.
Whatever happens Thursday into Friday, the storm and the associated polar jet amplification sets the stage for a cold and mostly dry weekend with readings falling to near zero Friday and struggling to reach 10 on the mountain Saturday January 8th. Reading should moderate somewhat by Sunday the 9th.
The marginally favorable pattern described in the first paragraph appears somewhat encouraging for Vermont but does not appear capable of sustaining arctic cold in the Ohio Valley or Mid-Atlantic states. We can put a positive spin on this situation by suggesting that an overwhelmingly cold pattern is often not a particularly snowy one in Vermont in January. The widespread area of cold across eastern North America is expected to quickly give way to normal and even above normal temperatures in some areas to our south. Meanwhile the center of the polar vortex will reposition itself in eastern Canada, keeping much of New England and especially Vermont within Vermont's reach. We should thus see a reinforcing shot of winter chill around January 10th and 11th with additional chances at least lighter snowfall throughout that 2nd full week of January.
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