Sunday, December 10, 2017

First significant snow Tuesday/Wednesday and I am starting to like the Christmas outlook

Got a few inches in the bag and should have plenty more to come in the coming days and even weeks. I'll readily admit that at the time of the last blog update, there was legitimate concern that this entire pattern might flop around Christmas Eve. Just in the last 36 hours or so, there have more definitive indications that the jet stream in the Pacific Ocean, though tightening slightly next week, will loosen substantially right around Christmas Day sending the EPO index back into more favorable negative territory. The 6-year consecutive stretch of Christmas thaws is thus in jeopardy but not yet eliminated (eliminating it now would obviously jinx it and ensure 60 degree weather by the 26th).

First thing is first however, a significant storm system on Tuesday. Was surprised on Sunday to see the National Weather Service in Burlington lower accumulations  (2-4")for Tuesday and only advertise the event as "light snow". Perhaps it reflects some lingering uncertainty regarding the nature of the event. Though models have zeroed in on snowfall Tuesday, the storm's eventual strengthening or "bombing" in the Gulf of Maine remains a question. Both domestic models seem a little less bearish on the "bombing" than foreign counterparts. Sorry about the puns, it's just the way the sentence came out. Even without significant downstream strengthening, we will see more than 2-4 inches.

Snow should begin around daybreak Tuesday and for a time, should fall moderately and perhaps heavily for a few hours. I think the strengthening in the Gulf of Maine will be more substantial and though I think snowfall might taper to flurries by late Tuesday afternoon, 6-10 inches should be the expectation for high country locations like Mad River Glen. Snow will re intensify Tuesday night and continue as snow showers Wednesday as some of the coldest weather of the season so far builds across the area. There has been lots of talk about big time lake effect snow Wednesday because of the thermal situation around the Great Lakes. This applies to Lake Champlain as well and snow showers and squalls should be the result providing the mountains with additional accumulations. I am going to retain a little caution and suggest 8-16 inches over the two day (Tuesday/Wednesday) period but my gut wants to say 10-20". I'll leave both forecasts out there for now and let the chips fall where they may.

Temperatures will be in the teens and single numbers Wednesday and Thursday and we expect the east coast to get impacted by another clipper system later Thursday into Friday. Lots of uncertainty persists regarding this situation and snowfall is possible over a broad area but not guaranteed for anyone. The European model has been relatively consistent in its assessment that the storm and its snow will remain to the region's south but this model has its miscues over the last few weeks so it will be worth watching.

The pattern is expected to relax around the weekend of the 16th and 17th though cold weather will fight to remain in place across interior New England. Will a mild push of air coupled with a storm system late in the weekend bring another wintry weather situation to Vermont ? Could we see a limited stretch of above freezing temperatures ? Several possible outcomes here but either way, we should see colder weather return by Tuesday December 19th and persist through the middle of next week.

The longer range was already discussed but to reiterate, I was very encouraged to see varying ensembles suggest a weakened Pacific Jet as we head toward Xmas weekend. In addition, there are indications of a full fledged Omega blocking structure in the jet over Alaska and this more or less guarantees the presence of arctic air for New England and plenty of other places.

No comments: