Saturday, December 2, 2017

A few days away a big stretch of winter and maybe a week away from significant snows

It might be a little mild out there but early December is early December. Its always very dark and typically there isn't a lot of snow on the ground. We expect that all to change within the next week or two and we are going to try and zero in on some details but it's still a challenge as we remain several days away from a significant snow.

After a series of sub-freezing nights, we can expect about a 48 hour stretch of above freezing temperatures (somewhat less than that above 2500 feet) beginning Monday afternoon and persisting through Wednesday afternoon. The front marking the end of the thaw will also mark the beginning of a  new and very improved pattern. The front will also bring a few hours of modest rainfall to the entire state Tuesday evening along with 45-50 degree temperatures. The rain is all done by Wednesday, the above freezing temperatures are done by Wednesday evening and away we go.

The initial blast of cold will have modified substantially before reaching New England and is taking the scenic root across the Ohio Valley. We can still expect flurries to commence by later Wednesday and continue into Thursday though I am skeptical about accumulations amounting to much. The real question relates to the lingering baraclinicity (a fancy word for temperature boundary) that will remain just offshore. It won't take much to ignite a coastal system on the 9th/10th which is why I described the environment to be a "tinder box" in a tweet the other day. Opinions vary on the viability of storm but Vermont has some optionality. We can get a dose of snow from a potential coastal system which would more likely be Saturday or receive a potentially greater gift if a dymanic clipper system becomes the dominant feature and produces both synoptic snow and lake/terrain enhanced snow Sunday. Can't guarantee anything this early but if I were a betting man, I would take the "over" on at least 6 inches by the end of the weekend.

Not too many changes to the longer range outlook as of the weekend which is a "no news is good news situation". The pattern looks excellent, propelled mostly by a very negative Arctic Oscillation and a big assist from a positive PNA. Another significant "clipper-like" disturbance is likely to bring additional snows to the high country in the Monday/Tuesday time frame ahead of what should be a more significant surge of cold air. Since the air isn't overwhelmingly cold (modestly cold) we get the added benefit of keeping the boundary layer on the unstable side. Particularly intense shots of arctic air can be both very dry and bring a shallow very stable layer to the atmospheric preventing snowfall. All that said, I expect additional snowfall later in the week.

The looming question and I mean the very looming question relates to the Christmas holiday and whether or not this pattern can continue into Christmas week. I can promise good things until about the Winter Solstice but patterns such as this are often interrupted during La Nina years and do not typically last a month or longer. There aren't any ominous signs way out on the horizon but lets be cautious for now.

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