Thursday, December 20, 2018

Thaw looks increasingly damaging Friday, longer range looks a bit more promising

No, the situation this Friday is hardly ideal and the news hasn't gotten any better over the last few days. Based on the latest data, the track of this rainy weather system appears both farther north and less occluded which means southerly winds driving very warm air into the entire state. Rain begins Thursday night with temperatures in the 30's and will become periodically heavy by daybreak as temperatures warm slightly. The big rise in temperatures occurs during the day and will correspond to an increase in snow-eating southerly winds. As temperatures peak in the low 50's in many spots, thunderstorms are possible before most of the heavy stuff pushes off to the east during the evening. Really no way to sugarcoat this set of circumstances anymore, it will be a damaging thaw for ski areas across the entire state. Fortunately, there is some good news in the longer range outlook. Gradually we will gain access to more cold air and although the possibility remains for another mitigated thaw around the 29th, the chances for snowfall will grow in frequency as we advance toward 2019.

Colder air arrives Saturday but it will take some time, probably most of the day below 2500 feet, for temperatures to fall back below the freezing mark. The higher elevations across the northern half of the will see a bit of snow and the summits can expect a small accumulation, but with the exception of Jay Peak, I wouldn't expect much more than a rather paltry consolation prize after Friday's washout. We should see a limited return of sunshine on Sunday with calmer winds and sub-freezing temperatures ranging from the high teens in the morning to near 30 in the afternoon.

The first system worth watching arrives early on Christmas Eve. This is a clipper system of total insignificance that will attain some limited southern stream moisture and thus bears watching because these situations are often fluid and are often decided late in the forecast game. Snow would begin prior to daybreak and persist through at least part of the day. Accumulations appear to be pretty light but again, things can change. Christmas Day continues to appear dry but there is a weaker impulse on the weather map that could keep the snow flurry activity going and also help entrench some needed cold into the state. This airmass should keep the mountain sub-freezing through Thursday and a piece of a intensifying system in the Rocky Mountain region could still spread some snow into the state some time in this time frame though this appears less likely today verses a few days ago.

The aforementioned Rocky Mountain storm is indicated to take another less than optimal track late next week but thanks to the presence of more arctic cold, we remain in the mix for wintry precipitation. Another period of above freezing temperatures is also a possibility but this surge of warmth appears less both less intense and shorter in duration if it were to occur at all.

Though the longer range outlook, the part that includes the New Years holiday and beyond, continues to appear relatively neutral, there are indications of more snow possibilities. The better part of this story is the descending NAO index and the possibility that this evolves into a high latitude blocking event that helps anchor the pattern around and beyond New Years holiday. This wouldn't be the type of pattern to deliver bone chilling cold, such as what we got early in 2018, and I am not sure we really want that. Instead, it could be the pattern that sets the stage for a few winter storms which will be much needed after this latest sub-tropical breach.

5 comments:

Unknown said...

Can you elaborate about why a December thaw occurs so regularly in the Northeast right around Christmas? Is it a coincidence, or are there underlying meteorological factors?

pog said...

Im quite bored with the rain stuff on christmas holiday, hope will have a better january than last year.

Lisa said...

Yes curious to hear why rain like this always on Christmas. Uhh

RyanBD said...
This comment has been removed by the author.
RyanBD said...

I recall last january as being pretty good? Brutally cold, but the snow was good and jt made for short lift lines. Am I mistaken?