Plain-language summary:
After a brief, modest thaw yesterday, it is turning much colder today, with a modest snowstorm from southern Vermont to Maine tonight. Afterward, it will be very cold through Wednesday, then turning somewhat milder through next weekend, with a few snow showers but a somewhat bigger snowstorm along the Maine coast being possible then. It may turn slightly stormier early the following week, though yet again, the chances of storminess appears to be lower than it did days ago, and it will likely be mostly dry again for a while afterward.
Meteorological discussion:
Modest snowstorm in southern areas tonight
After a brief modest thaw for lower elevations yesterday, arctic air is pushing back in straight from the north. At the same time, a strengthening low pressure system in Virginia this afternoon will quickly move northeastward to New Brunswick by late tonight, leading to a swath of plowable snow on the northwestern side of the storm, including southern Vermont, southern New Hampshire, and southern and eastern Maine, where snowfall rates could briefly reach 1"/hr (2-3 cm/hr), but the fast movement and rather late strengthening of the storm will prevent heavy snow rates from persisting over a given location for more than a few hours. Northwest of there, only light snow will fall, and from the St. Lawrence Valley on northwest, no snow at all is expected. Had this storm been stronger and the upper-level pattern more amplified like shown by the models a week ago, it would have been a widespread big snowstorm for our region, but yet again, the widespread big snowstorm appears elusive.
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| Source: PivotalWeather |
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| Source: PivotalWeather |
Very cold Monday through Wednesday, especially north of the U.S./Canada border
The coldest air mass of the season will encompass most of central and eastern North America on Monday and Tuesday, with widespread below 0F (-18C) temperatures in our region at night away from the Atlantic Ocean, though broadly speaking, the most anomalous cold will go to our south as the amplified pattern sends the cold high pressure system down the Rockies and then into the southern U.S. More locally, a subtle disturbance across the Great Lakes will turn the flow to more westerly or southwesterly by Tuesday morning south of the U.S./Canada border, leading to some clouds preventing radiational cooling, a few snow showers, and moderation from the Great Lakes, with the extreme cold down to -22F (-30C) staying north of the St. Lawrence Valley. Inland Maine will remain far enough away from this disturbance Monday and Tuesday nights to remain clear, calm, and very cold. The flow will never turn northerly again for the rest of the week, due to a weak clipper passing to the north of the region by Thursday, leading to more southwesterly flow, another limiting the intensity of the cold in our region. Given that this is the climatologically coldest time of the year, few if any cold records will be broken.
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| Source: TropicalTidbits |
Turning milder through next weekend and still mostly dry, perhaps except coastal Maine
This broad arctic air mass will suppress any moisture to the south for yet another week, with a coastal storm on Wednesday and Thursday likely bringing wintry precipitation to the southeast U.S. but likely south of even coastal New England. Afterward, a moisture-starved clipper will move into Ontario and Quebec north of our region, leading to a southwesterly flow and moderation of the arctic air mass, but still with little moisture. Another coastal storm could push northeastward and clip Maine if the upper-level trough associated with the Ontario and Quebec clipper is deep enough and negatively tilted (northwest to southeast) enough to pull the storm onshore, though given how far east and weak everything looks at this time, it is unlikely to spread any precipitation farther inland than coastal Maine. Instead, the clipper could bring a few snow showers Friday before winds possibly turn northwesterly or westerly, though it might actually be warmer than the prior days.
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