Tuesday, December 1, 2020

Onward and upward from here with temperatures slowly expected to chill and a possible storm this weekend

December arrives with temperatures well into the 50's across the MRV while temperatures in Tampa, FL were 49. This would illustrate the power of a phased and very strong storm system that tracked up through western New York. This recent storm would be a snow-eating abomination given the combined efforts of strong winds, high dewpoint temperatures, rain and even thunderstorms in many areas. There was little snow to lose across the state however and we continue to exist as we did in late November, albeit a little muddier and with higher river and creek levels. December mud is a little depressing for sure, but we got a few things going for us over the next two weeks and we should be headed in a positive direction on the snow front shortly and if we are lucky maybe we can hit one out of the park. 

Lingering instability from our recent storm will drift north-northeastward over the next two days through western Quebec up in Canada. Temperatures will eventually become cold enough to support snow flurries and snow showers across Vermont, especially the high country. That said, winds will never align properly for any significant accumulation and the best instability is well to our north. The high country will likely get a bit white but that's about it from what was a rather putrid storm on the whole for Vermont. Temperatures will also continue to remain on the mild side through Friday, just not as excessively so. High temperatures will continue to climb into the 40's in low lying areas with below freezing temperatures at night. 

Our eyes remain fixed on a second substantial southern streamer that we expect to be loosely positioned over Alabama/Mississippi on Friday. We still expect this storm to make a northward turn but models have been delivering varying results on whether not this storm is the 2nd to phase and become a massive precipitation producer for the east coast this weekend. The consensus suggests that indeed it will. Consensus also suggests that the track of this system will be much farther east and in fact mostly off shore putting the high country of Vermont in play for a bit of snow. Arctic cold or even any kind of cold is so sparse over lower North America and this will continue to present a challenge for those hoping for big snow, especially over low lying or coastal areas of the northeast. MRG is away from the coast obviously and a bit higher up giving us a shot at a decent accumulation of elevation sensitive snow given the track and evolution. 

Essentially we have a benign Canadian clipper system that will dive southeast Friday and attempt to phase with the aforementioned southern branch energy. I don't want to get too bogged down with the various scenarios except to say there's still a better chance something happens than it doesn't (Like 60/40). Even if the storm gets washed out to sea, the pattern will remain pretty dynamic albeit non-arctic. After a mild day Friday, we have a chance for some light snow Friday night, followed by the possible impact of said storm between Saturday and Monday. Even a big swing and a miss does not eliminate the chance for small amounts of snow showers/flurries from 1-2 different polar pacific impulses in this same time frame. Additionally, the pattern remains supportive enough for an additional chance snow later in the week. 

Regarding the uniqueness of this La Nina, non-arctic, but stormy pattern, the various ensembles suggest different evolutions, none of which are especially unfavorable. There are indications of a weaker push of milder temperatures around the time frame of December 12th and 13th. As this is happening however, both major ensemble packages indicate that a broad area of jet stream ridging across Scandinavia should help to flood much of Canada with Arctic air. The American Ensembles maintain that signal of a positive PNA structure and allowing that arctic air to be more of a force across the United States. The European less so but even this evolution would depict a pretty wintry Vermont in the period beginning December 13th to 17th. 

Needless to say, I am encouraged. It's wet and bare and pretty ugly out there but it won't be for too much longer. 

2 comments:

Chris said...

Is there any heuristic for knowing how quickly the ground can lose its heat so that snow will actually stay when it lands? It is so wet that it would seem to need several days of hard freeze to allow the ground to get cold enough so the snow will stick.

Knoll said...

Josh, I really appreciate your work on this blog. Thanks. I just got two powder alerts from On the Snow saying Kilington and Okemo were expecting dumps of 25” and 30” respectively on Sat. Has to be a typo, right?