Wednesday, December 23, 2020

Scrooge job for Christmas as expected and a downgrade for our potential storm 12/28-29

 No good tidings with our 'nightmare before Christmas' situation. It's as bad as we'd feared. We'll keep temps below freezing through early Christmas Eve but by midday, a modest south wind will push readings into the 40's and the abomination commences in the evening. Though it can depend on where you live in the valley, south winds can really rip down the valley unlike any other wind direction and I fully expect they will. We certainly could see some power outages and a few trees down on Christmas Eve night. Combined with temperatures/dewpoints well into the 40's and occasionally heavy rain we should expect to have any natural snow wiped out. Even our southern neighbors near Okemo and Ascutney who've been living large the past week will take quite a beating with not much left to show for all the good fortune. Just a classic Vermont Christmas Scrooge job ! 

Mild temps of near 50 degrees or even higher will actually linger through a good part of Christmas Day though the rain will have ended fairly early in the morning. The return to colder temperatures will be accompanied by snow flurries Friday night and that should continue into Saturday and Sunday. Farther north, these snow showers will amount to a few inches but our wind direction isn't especially favorable for Champlain/terrain enhanced snow. I expect maybe a fluffy inch or two total over the weekend across the high country around MRV and a dusting in the valley. 

I don't have especially great news in the week leading up to New Years. The storm track has shifted northward according to recent rounds of model data. A surprising turn of events from my perspective since, in this setup, it was actually the reverse I was more concerned with. The negative NAO, fueled by a building and ultimately massive jet stream ridge over southern Greenland will soon become the elephant in the room and I had concerns it would actually suppress storminess and keep the door open for a maritime "hang-up" situation. Still possible but the trend has been moving in reverse. There are many variables on a weather map and when focused on one thing, another thing ends up being missed. In this case, models are keying in on energy in the Pacific diving into the southwest US and amplifying. This would have the effect of steering the jet northward downstream were this to happen. Even these less than ideal circumstances keeps the door open for snow on Monday December 28th, just not as much of it and temperatures will be milder than I would like. It's pretty frustrating but I would stay tuned on the week. If comparing the weather to a game of Texas Holdem, a split jet stream is a pretty good hand to start with, and allows for several potential different winning hands. The "flop" and "river" cards might not help with the 28th but could allow for something later. I would also note that a worst case scenario for the 28th appears to be a few inches and not a total shutout.

That aforementioned jet energy in the US southwest will become the focal point around New Years for the next potential storm. It will actually be relatively chilly in between (Dec 29-31) with temperatures in the single numbers at night and teens and 20's during the day. Then the boat load of jet energy pushes east and should bring moisture and some sort of organized weather system. The split jet mentioned above should make some arctic cold available and it will take an adverse track of this storm to foul things up yet again. 

The general weather pattern has the same players performing the same roles for the most part. The negative -AO/NAO working for us with an irritated Pacific working somewhat against us though it will continue to feed us storm opportunities. I would reiterate how dominant the ridge over southern Greenland appears as we head toward the New Year. It dwarfs about every other jet stream feature across the entirety of the northern hemisphere and is certainly strong enough to throw a few knuckle balls our way in early 2021. New England's proximity to this weather feature would conceivably allow some relative warmth to be advected into the region from the Canadian Maritimes. I would prefer however that a storm finds a nice place to stall somewhere downstream and provide Vermont with a never ending conveyor of snowfall. For the time being though, a best guess for Vermont is that we start 2021 on the slightly milder than average side but with decent chance still of scoring some significant natural snow. 







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