It's not a friendly update in the shorter or longer range today and I think the best thing we can do is simply establish that it should be a a month of low expectations and hopefully we can surprise to the upside from a low bar. Speaking frankly, we have a dreadful collection of teleconnection fundamentals while we continue to face warm ocean/lake water temperature feedbacks stemming from months of warm weather. There are some in the weather forecasting community suggesting a return to colder/more wintry weather by Christmas and I will talk about that more in depth a few paragraph's down but personally I am pessimistic we will see any sustained stretch of wintry weather after December 10th until January '22. With colder temperatures close by in Canada, we could see multi-day stretches of cold weather and some snow but more generally speaking, this will be a challenging last three week of December, there's just no getting around it.
Regarding the midweek threat of snow, it has not vanished entirely but almost entirely . The system currently centered near Grand Teton National Park is simply not very robust, and is not expected to be as it migrates into the central Plains Tuesday. A wave of low pressure is still expected to evolve into a more organized storm along the eastern seaboard by early Wednesday but without the help of a more potent Midwest weather system, it is difficult to imagine a big east coast weather producing system evolving from this and models are not suggesting there is one. In other words, we need more than just a "northward shift" we need a stronger storm. Light snow can still be expected Wednesday, enough to whiten the ground with 1-3 inches, but a big storm has gotten more and more unlikely. After the thaw on Monday we can expect sub-freezing temperatures through Friday with some sunshine on Tuesday, some more on Thursday while Wednesday features the aforementioned light snow. More light snow is possible very early Friday ahead of the push of much milder temperatures.
This first push warmer weather Saturday looks especially ferocious and we can be glad about not having any deep early season snow because most of that would get wiped out by the combination of near 60-degree temperatures, wind and a period of rain. There are some question marks relating to a wave of low pressure that could become a well organized east coast area of low pressure. This storm will have a weakening area of cold to work with but there are scenarios that could include a mild rain to snow situation on Sunday. Both the European and American models have suggested such at various times but data is not illustrating any confidence inspiring consistency that such a scenario will occur. Regardless, we will get a return to colder weather for a day or two beginning Sunday before again facing the music of a very bad weather pattern.
More specifically on next week, the large warm weather producing jet stream ridge is expected to set up over the middle of the United States placing New England in the warm but front flank part of this expansive weather feature. This does give us the silver lining of both pleasant weather and a continuation of mostly sub-freezing nights which enable snow making operations to continue. I've seen a few simulations suggesting an area of more legitimate cold could save interior New England from a multi-day thaw. This is possible but at the very least I would expect a few above-freezing days and certainly not a lot of natural snowfall if any.
Getting back to the longer range/holiday speculation talk, I've seen some speculation regarding a pattern change around Christmas stemming from some weakening of what is expected to be a strong Pacific jet stream. The basis for this is the expectation that the Madden Julian Oscillation appears fluid as opposed to stagnant and poised to move into Phase 7, which is a more neutral phase for winter weather in eastern North America as opposed to the current phase 6 which is considered mild. The fluid nature of the MJO is certainly encouraging but it's going to take some time to break down the current combination of unfavorable teleconnection indices. Aside from the strong/tight jet stream in the Pacifc, we still have a very unblocked pattern at high latitudes highlighted by an Arctic Oscillation projected to range between a +1 and +2 for the next 2 weeks. A negative AO is absolutely vital for winter weather south of 40N and fairly important (though not vital) for winter weather in Vermont, especially in December. That said, I would like to seem some stronger evidence that the prevailing "unblocked" jet stream regime will break down.
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