Meteorological discussion:
A moisture-starved Alberta clipper will pass to the north on Monday, leading to southerly flow and mild temperatures. Scattered rain showers are likely along and just ahead of the clipper’s cold front, with it briefly changing to snow at the end for northern areas as colder air briefly enters Monday night. Another Alberta clipper will follow just behind on Tuesday, with it once again going to the north, but only slightly this time. This leads to mild temperatures again for most, except in the St. Lawrence Valley where low-level cold air from the northeast will channel through the valley. A potent upper-level vorticity maximum will traverse the region, leading to briefly heavy rain or snow showers, especially in higher terrain, with graupel and/or small hail being possible. Any rain or graupel will turn to snow and end Tuesday night with the clipper’s cold front.
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| Source: TropicalTidbits |
An broad arctic and very cold high pressure will encompass much of southern Canada by Wednesday, and the cold air will filter into New England but not be able to push farther south due to the combination of a deepening trough in the western U.S. and an incredibly strong and warm ridge building over the Gulf of Mexico and southern U.S. The system in the western U.S. will eject into the Plains in two pieces, both of which will move eastward into the battle zone. The two pieces will lead to a low pressure area very elongated from west to east acting as a front. Record high temps are expected on Thursday in the Ohio Valley, mid-Atlantic U.S., and southern U.S. with widespread 77-86F (25-30C)! A prolonged period of snow and ice will occur to the north of the battle zone, from the Northern Plains to Northern New England and southeastern Canada with maxima of >25 mm of ice accretion and >30 cm of snow. In this area, the record warmth from the south will be forced to rise over the low-level cold, arctic air mass, causing the water vapor to condense and fall as precipitation.
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| Source: PivotalWeather |
Precipitation will likely start as snow for all of Northern New England and southeastern Canada Wednesday night with the first piece of energy, but change to ice from the southern Adirondacks to southern Vermont by later Thursday as warm advection in the mid-levels occurs. The above-freezing layer aloft could approach the U.S./Canada border Thursday evening as the battle zone and its accompanying precipitation slowly moves north into Quebec and northern Maine and weakens. The low-level arctic air will be difficult to scour out, leading to ice pellets south of the U.S./Canada border, though those areas could get mostly dry slotted once the warm air aloft moves in. Areas north of the U.S./Canada border will see all snow, but areas too far north will miss out on the heaviest precipitation (e.g. from Quebec City to northern Maine on north). Even outside the dry slot, precipitation will lighten temporarily Thursday night as warm advection stops and area is sort of left in between the two low-pressure areas. The second piece will track just north of the first piece but will be accompanied by falling heights, leading to a short period of heavier precipitation and cooling aloft, and any ice will change over to snow. Unlike with the first piece, the precipitation from the second piece could be mainly north of 44°N or 45°N, but that really depends on how the two pieces eject into the Plains, and we will not have those details for another 2 days.
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| Source: TropicalTidbits |
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| Source: TropicalTidbits |
Behind the second low pressure, the cold arctic air that would have been sitting in Canada will surge southward into the mid-Atlantic U.S., but the Gulf of Mexico ridge will be resilient and prevent the cold air from surging to the Gulf Coast. Instead, another storm will move into the western U.S. and partly eject into the Plains by Saturday, likely farther south than the mid-week storm. Unlike the mid-week storm though, this storm appears to be weaker, and the high pressure will be to the east and northeast, rather than encompassing all of southern Canada. This allows for a broader area of warm advection and precipitation to the northeast of the low pressure center. There could also be another low pressure over northern Ontario to complicate the pattern. For now, it appears as though the two disturbances will not phase, and we will be left with a widespread light to moderate snow over the region, with locally heavier amounts in southern facing slopes due to upsloping. A last minute strengthening could occur as the storm reaches New England. However, a lot can still change until then.
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| Source: TropicalTidbits |
Beyond next week, the NAO will likely turn negative, indicative of the Greenland blocking and equatorward displacement of polar air masses triggered by the sudden stratospheric warming event. Meanwhile, a -PNA will continue to lead to a trough in western North America, where the coldest air will likely be. But the Greenland blocking will likely stop most storms ejecting into the Plains from cutting into Ontario and Quebec and instead lead them to slide underneath the blocking, perhaps through the mid-Atlantic U.S. or southern New England. Although it is unlikely to be especially cold in this pattern, it does not look warm either, and this farther south storm track would lead to frequent snow and ice opportunities through early March, even if the big East Coast cities continue to see mostly rain.
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| Source: Climate Prediction Center |
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| Source: TropicalTidbits |
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