Plain-language summary:
After being quite cold on Friday and
Saturday, it is milder today. An intensifying but quick-moving storm will
produce rain at lower elevations and wet snow over higher elevations tonight
into tomorrow, with the heaviest over the Green and White Mountains and northern/western
Maine. It turns much colder Tuesday and Wednesday with lake-effect snow in the southern Adirondacks and scattered snow showers
elsewhere before it turns milder with a moisture-starved Alberta clipper bringing light
snow in the Adirondacks and Quebec Wednesday night. Two storm could bring rain or snow from Friday through the following Monday,
depending on their strengths and trajectories as well as just how cold the air mass
is ahead of them. For the following week, the weather pattern favors
slower-moving storms tracking farther south along with modestly cold air, which
would lead to a Nor’easter snowstorm if the pieces align well.
Meteorological discussion:
Although it was quite cold on Friday
and Saturday with an arctic high pressure system, the high pressure is moving
offshore and the cold air is growing stale. Meanwhile, a low pressure system
over northern Ontario is forcing southerly flow and warm advection into our region,
while at the same time, a southern disturbance will form a quick-moving but
quickly intensifying coastal storm that will move northeastward into southern
New England tonight and Maine tomorrow. Due to the deep-layer warm
advection ahead of the coastal storm, the boundary layer will be too warm to
snow in lower elevation locations except possibly a brief mix at the start in
the St. Lawrence Valley and during the heaviest precipitation elsewhere. However, it will be somewhat cooler aloft, and higher elevations
of the Adirondacks and Laurentians will see at least light snowfall. As the
coastal storm intensifies, there will be heavier snow in the Green and White
Mountains and northern/western Maine, though even there, it will be a
relatively wet snow, and combined with the speed of the storm, few places will
see >6” (>15 cm).
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| Source: TropicalTidbits |
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| Source: TropicalTidbits |
As the storm continues to strengthen
over the Gulf of St. Lawrence Monday night into Tuesday, much colder air will move
into our region with brisk northwesterly winds. The broad, deep upper-level
trough with a weak disturbance rotating around it will bring scattered snow
showers Tuesday evening, with northwestern slopes being favored for some light
snow accumulation. The westerly flow off the still warm Lake Ontario waters will also lead to lake-effect snow in the southern Adirondacks, enhanced by upslope. Afterward, a moisture-starved Alberta clipper will push east
into Quebec by Wednesday night, scouring out most of the cold air, though it
could still be cold enough for scattered snow showers, especially in higher terrain.
Given the storm track to the north, most of the snow will be limited to the
Laurentians and possibly the Eastern Townships of Quebec.
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| Source: TropicalTidbits |
There might be a brief shot of cold
air behind the clipper, but it appears that a trough entering the western U.S.
will force a ridge to develop in the eastern U.S., deflecting most of the cold
air back to the north. How much cold air remains in our region will be critical
to the weather later in the week and the weekend. One of the disturbances rotating
around the trough will develop a storm in the Plains that will move
northeastward Friday, possibly into the southern Great Lakes region, but this track is uncertain with great model disagreement. Since most of the
cold air will have been scoured out, there is a relatively narrow passageway for
the storm to produce snow, and wet snow at that: it has to go just far enough north and be strong
enough to bring the moisture but yet not bring strong warm advection that would
quickly turn the precipitation to rain. Another messy storm is possible Sunday into the following Monday.
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