Plain-language summary:
After bringing rain, ice, and snow last night depending on location, a storm slowing down over Maine and New Brunswick will provide light snows to northern Maine and areas along and northwest of the Appalachians this afternoon through early Monday morning. It will then dry and at least partially clear out with weakening winds through the remainder of the week, marking the longest dry spell in weeks. It then likely turns milder with rain Friday, though the weather setup is still rather uncertain, and there is still the outside chance of some areas seeing wintry precipitation. More milder surges with rain are possible or likely the following week, though it might not be as warm as some recent late fall warm periods. Colder and possibly stormy weather will likely return for the end of November, with precipitation type dependent on exact storm tracks which are uncertain at this time.
Meteorological discussion:
Alberta Clipper brings more mixed precipitation changing to snow and windy conditions this afternoon into Monday morning
Despite a push of extremely warm (for November) air into the Plains and even the western Great Lakes, the leftover upper-level trough from the past week's arctic surge, now in Atlantic Canada, steered a more dynamic Alberta clipper than usual southeastward into our region, blocking the warmup and instead giving a round of rain, ice, and snow last night depending on location. A surge of colder air is coming in this afternoon, with any precipitation falling as snow this evening into tonight. Often times, it quickly dries out on the back side of a storm, but in this case, a deepening upper-level trough will transform into a cut-off low straight over our region, tracking from northern Vermont to central Maine through early Monday. This will lead to continued light snow in northern Maine and many areas along and northwest of the Appalachians, with heavy snow accumulation in the higher elevations. Areas southeast of the Appalachians will be too far south relative to the storm and will also receive downsloping wind off the Appalachians, leading to dry weather there. It will be breezy everywhere with a strong pressure gradient resulting from the 975 mb surface low-pressure system over New Brunswick occluding and slowing down.
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| Source: TropicalTidbits |
At least partial clearing with weakening winds and longest dry spell in weeks later in week, then likely milder with rain at some point Friday into next weekend
After Monday's storm slowly pushes east of our region by Tuesday, it will at least partially clear out with winds weakening, though without a very dry air mass in place, there could still be lingering low clouds with such an air mass at this time of year. It will feature the longest dry stretch in weeks, with the next system being a relatively-starved Alberta clipper quickly moving southeastward on Friday. Given the track to the north and southerly winds ahead of it, the already stale cold air will be scoured out, leading to mainly rain for most, though there may be wet snow or other wintry precipitation in some northern areas. The clipper will bring a reinforcing shot of modestly colder air behind it, but it will not be intense and will be relatively brief. The
critical -AO, -NAO, and +PNA combination recently that brought all the
cold air over the past week will be neutralizing next week, making it
difficult for cold air to penetrate deep into the mid-latitudes again
for a while. Arctic Canada will also remain unusually warm. It gets quite uncertain afterward, depending on how a southern system to the southwest of the clipper interacts with the Alberta clipper. The southern system will only very slowly move eastward from the southern Rockies into the Plains and then Great Lakes over the course of the week due to it being mostly cut-off from the main jet stream to the north and underneath broad upper-level ridging across western and central North America. If it comes into our region just at the right time, such as right as the modest cold air moves in behind the Alberta clipper, northern areas could at least start as wintry precipitation before changing to rain. However, the system could be delayed enough for the cold air will grow stale or could be suppressed to the south entirely.
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| Source: TropicalTidbits |
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| Source: TropicalTidbits |
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| Source: Climate Prediction Center |
Milder weather pattern with more rain events likely the following week, then colder and potentially still stormy
The relative lack of wintry precipitation will likely continue for a while afterwards, though confidence is low in any details. That by itself is actually not unusual for November. The PNA will turn negative for a time, with the upper-level trough in western North America promoting a downstream ridge in eastern North America. This would promote more storms ejecting from the Rockies and tracking northwest of our region, leading to more mild surges and rain events in our region, unless there is just enough high-latitude upper-level ridging with surface high-pressure over northeastern Canada to keep low-level cooler air in our region, which is still possible if the NAO remains slightly negative and could lead to sneaky areas of wet snow, ice pellets, and freezing rain. However, there are signs that the North American weather pattern will favor more discharge of arctic air into central and eastern North America towards the end of November with -EPO and upper-level ridging in Alaska. If the upper-level trough initially sets up to our west, a lot of the cold air will go there initially, with the southeast U.S. ridge deflecting storms toward our region, perhaps leading to a stormier and snowier period, with mixed precipitation still possible if the weather pattern is amplified enough. That would be a weather pattern in which relatively small shifts would make a difference between cold and snowy conditions and mild and rainy conditions, leading to greater uncertainty.
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| Source: TropicalTidbits |
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