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Monday, December 25, 2023

Short term rainy outlook could be overshadowed New Year's weekend surprise !

 I hope everyone enjoyed this year's Christmas holiday even without the deep snow we once had. The holiday season has had a recent history littered with thaws and rain events and we can add 2023 to the list. A very disorganized and slow moving storm system is telegraphed to approach interior New England Tuesday night and promises to continue the stretch of cloudiness we have seen through the end of the week and even into New Year's weekend. More on that in a minute. There remains very little cold air to work with as has been advertised for several updates. Even a more favorable trajectory of this storm will fail to alter another wet outcome at least initially. Rain will arrive Wednesday morning and continue sporadically through Wednesday night into Thursday. No flooding risk with this event as the rain appears lighter, more intermittent colder and will be falling over minimal snow cover. The storm responsible for the initial dose of wet weather is anchored by a slow moving upper level closed low and as it moves a little closer to the area Thursday we might begin to see some mixed precipitation and snow above 3,000 feet but accumulations by Thursday night will be light and mostly insignificant. In short, the first 72 hours is the worst part of the current outlook; after that, things get better. 

Right off the bat, we have some big question marks that still remain unanswered and will determine the fate of New Year's weekend. The same closed upper low pressure center will slowly continue to spin eastward on Friday and as it does so, it gets a big shortwave injection of jet energy diving south out of the Hudson Bay. This is all part of a realigning weather pattern that can't happen soon enough, but this late Friday infusion of energy is critical and if we can achieve the right kind of phase, it will result in an amazing result for the weekend. We've had one model hammering away at this solution Christmas day, the Canadian model while another, the European model has been showing hints. What's this result you ask ? How about any rain or drizzle Friday turning to heavy snow and continuing through a good part of Saturday yeilding a foot-plus of powder for the northern Vermont high country ? Yes, this result is in play ! I can't make any promises yet, as this outcome is entirely contingent on the timing of that "kicker" system diving south out of the Hudson Bay which brings both the energy and the late supply of colder weather that's been missing all week. After glancing at the Christmas evening run of the Euro ensemble, I am willing to place chances for heavy snow at about 30 percent while the remaining 70 percent consists of either a lighter snow or a miss. We aren't categorically "cold" yet this weekend but we should stay sub-freezing on the mountain whether or not we receive the goods with temperatures staying mostly in the 20's or low 30's with clouds limiting daily temperature ranges. 

More generally, the playing field after the next few days has plenty of prospects. Case in point, the American GFS model has us missing the event on Saturday but potentially scoring a few days after that. Meanwhile, colder arctic air will get a chance to envelop northern parts of the North American continent and finally get a chance to have a greater say on weather in Vermont by the first full weekend of January. We have just a picture perfect split flow look just ahead of this aforementioned weekend and this gives us an excellent chance to spin up a substantial snow event of some kind between January 4th (a Thursday) and January 6th (a Saturday). After that, it becomes a mixed bag of indicators with help coming from the NAO which appears lined up to be solidly negative for the first 10 days of January and some lesser help from the AO which is expected to gently support more arctic air over much of Canada. I am a little bothered by action in the Pacific as we move toward January 8th (2nd Monday of the month), but conflicting teleconnections have proven to be an effective combination during the middle of winter.


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