Plain-language summary:
After a seasonably cold and dry Sunday, intermittent snow showers from Monday to Tuesday night will bring light snow accumulations to lower elevations and moderate accumulations to the higher terrain of the Adirondacks, Laurentians, and Green and White Mountains. After a dry Wednesday, a little snow is possible late Thursday into Friday before a brief warmup next weekend, possibly accompanied by a little snow. There is the uncertain potential of a snowstorm early the following week before a very cold arctic air mass settles in. It still will likely eventually turn stormier later in January, though it might be delayed compared to earlier expectations.
Meteorological discussion:
Cold and dry today, then intermittent snow showers with clipper Monday through Tuesday night
It is seasonably cold and dry today in the wake of a disjointed system that could have been a bigger Nor'easter had the disturbances interacted more favorably. Another clipper will move into Ontario and Quebec, mostly north of our region from Monday into Tuesday. This means that the steady snow will pass well to the north of our region, with our region receiving intermittent snow showers instead, mostly in higher elevations and on the western slopes of the Appalachians given the modest westerly flow. The elongated nature of the clipper will lead to a prolonged period of intermittent snow showers. It will also turn milder, but without any strong southerly flow of warmth and moisture, it will merely approach freezing at lower elevations with little precipitation. Some of the snow showers could be convective given the saturated and moist adiabatic profile up to 700 hPa, and snow ratios in these cells are likely to be quite high, 20-30:1, due to the enhanced ascent through the dendritic growth zone. The surface low pressure will "jump" to just offshore the New England coast by Tuesday night, changing the flow to northwesterly and shifting the resulting snow showers to the northwesterly facing slopes as it turns colder again, though not bitterly cold with the cold air mass cutting off, like last week. High pressure and drier air will shut off the snow by Wednesday.
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| Source: TropicalTidbits |
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| Source: TropicalTidbits |
Possible more light snow Friday, then brief warmup next weekend, then possible snowstorm a few days later
Later in the week, the weather pattern speeds up somewhat as the -NAO weakens. A clipper will dive southeastward on Thursday and Friday but likely will weaken before reaching our region, leading to perhaps a little snow. A stronger system will likely pass to our north next weekend, with a potential brief thaw though it appears unlikely to get substantially above freezing even at the lower elevations, and there could even be some snow, especially on the south-facing slopes of the Laurentians, Adirondacks, and Green and White Mountains, with the Champlain Valley likely not getting much due to downsloping. After that, it turns quite uncertain. Even with the -NAO weakening and even turning positive, along with the AO turning positive, the persistent ridge along the West Coast of North America (+PNA) extending all the way to Alaska (-EPO) will promote a surge of very cold arctic air into the central U.S., even colder than what we have seen so far this January, with an associated upper-level trough digging into the Rockies. If next weekend's storm does not destroy the western Atlantic ridge too much, this is a favorable configuration for systems to eject out of the Rockies, move northeastward, and bring storms laden with Gulf of Mexico moisture into our region. However, latest model runs suggest that the extreme cold could simply suppress storminess to our south or prevent much moisture from pushing northward even with a rather favorable storm track, a change from model output a few days ago showing a less intense arctic air mass and less suppression. This would be a different version of suppression than early January (pure ferocity of cold air instead of strong upper-level low in Atlantic Canada) that would continue an amazingly dry January. But the outcome is very sensitive to the timing and interaction between numerous disturbances, making it very complicated, so there will not be any real confidence in any scenario for at least a few more days, and we cannot rule out a snowstorm yet, especially for areas south of the U.S./Canada border.
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| Source: TropicalTidbits |
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| Source: Climate Prediction Center |
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