Mild air now encompasses a massive swath of North America as it has for much of the month. There are changes in sight with our temperature outlook but they remain down the road just a little bit. Most importantly for northern New England, is that the mild air will be tame on the scale of these things this week. Low lying areas around the MRV can expect several hours of above freezing temperatures (though not consecutive) between Tuesday afternoon and early Thursday, but those hours will just be within a few degrees of freezing as opposed to 10, 15 or 20 degrees from freezing. And then there's the best part of all this, the possibility for a significant snow on very late on Thursday into Friday. With cold air in such limited supply across eastern Canada, there is not a lot of room for error with the storm late this week but with each passing day, substantial snow looks like the most likely outcome.
In the mean time, the MLK holiday features a unique looking storm which has managed to spread clouds back into Vermont and both snow and mixed precipitation across eastern New England (mainly Maine). This storm appears extra-tropical in nature which would be categorically similar to the "Perfect Storm" of October 1991, though not as strong. What this unusual system has been able to do is throw a lot of mild air into northern New England, but mainly just above the surface. Temperatures at the summit of Mt Washington are expected to climb and may actually exceed the freezing mark late on Tuesday. This is not entirely unprecedented but it is unusual without strong warm advection from the south. The clouds over the MRV are expected to be with us for a while and I don't want to understate that. If we don't see a few breaks in the overcast Wednesday or early Thursday (possible) we could be looking at another week of overcast conditions. We can also expect some very light mixed precipitation Tuesday night which will primarily become snow showers across our high country on Wednesday. The flow would favor best accumulations north of us and temperatures will be hovering close to or just below the freezing mark above 2000 feet and above the freezing mark below that, but 1-2 inches in those elevated locations I just mentioned is still likely.
We will be precipitation-free early Thursday but unless we can squeeze some very early sunshine out of this day, clouds from the next system will envelop us as temperatures continue to hover in the lower or middle 30's. The approaching storm will be approaching the southern Great Lakes on Thursday in a very ominous way, but will make a tidy transition to the Jersey coast on Thursday evening and will be safely south of the Cape early Friday. As this is happening, northern Vermont will be entraining just enough dry air from Canada to keep our critical layers of the lower troposphere below freezing, at least that is the thinking right now. So, any mixed precipitation Thursday evening will become snow and accumulate at a rather decent one to occasionally two inch an hour rate before the ski day Friday. During the ski day Friday the snow will become lighter and eventually taper flurries by late in the day. It is a storm more typical of later in the season, but I'll take them any way I can get them. Unless we get a late curve ball, 8-16 much needed inches is my current target.
Our late week snow producing storm is the first of what appears to be a very active setup as the pattern transitions from the one producing the "atmospheric river" over California, to one which looks very much like a traditional La Nina. By late in the month, I think it will be southern Canada that experiences the most dramatic change with much colder air encompassing a region that has been excessively mild for several weeks. The Pacific jet stream in a typical La Nina set up is still irritatingly strong and it will be in our evolving pattern but aimed farther north and taking its energy on the Pacific Northwest and Canadian Rockies as opposed to California. This storminess will continue to impact interior New England after Friday with a subsequent weather system taking aim at us in the late Sunday January 22nd to Monday January 23rd time frame and yet another in the middle part of the ensuing week. Each of these storms could result in additional snow or snow/mixed precipitation or mixed precipitation with a little rain. During this time frame, a mildly negative AO combined with the ridging over Alaska will allow arctic to slowly progress southward and get involved in our day to day weather. It won't happen right away but as we move toward the later part of next week into the last full weekend of January, New England could finally see some below normal January cold of significance.
The next few weeks won't lack for excitement and there should be plenty to discuss and I expect we see our coldest weather of the winter season sometime between January 28th and Valentines Day. Even a cold La Nina set up can be rough for more southern latitude winter weather lovers however so not everyone will benefit. Colder airmasses will be in a constant battle with mild air across the southeast which will keep the ferocity of winter in check below 40 N latitude. At our latitude, we are certainly a good candidate for a big snow event over the next few weeks but are also at risk that an early amplifier that turns inland runner.
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