Very mild week after light snow Monday night; possible record warmth Thursday into early Friday before briefly colder for weekend; warmup afterward but more wintry weather likely to close February and perhaps beyond

Plain-language summary:

After a little snow from the Adirondacks on northeastward Monday night into Tuesday morning, a very mild week is coming up. Daily record highs could be broken from the southern Adirondacks to southern Maine on Thursday and Friday as two storms track to the north. The storms will likely bring rain even up to Quebec City and northern Maine, with more showery precipitation farther south along the cold front. However, the evolution and timing of the second system is still somewhat uncertain, and a little snow and ice cannot be ruled out in northern areas with the second system. It turns colder for the weekend but only briefly before a more modest warmup occurs next week, possibly with more rain. However, it looks somewhat colder to finish out February, especially north of the U.S./Canada border, and potentially stormy, with snow more likely in farther north areas. A sudden stratospheric warming event could lead to more wintry weather in March, but that is still uncertain.

Meteorological discussion:

In the midst of a mild pattern, a shortwave will dive out of northern Ontario into northern New England late Monday into Monday night. This trajectory might be aided by the northerly flow on the back side of the slow-moving cut-off low that will be moving off the U.S. East Coast. As the shortwave will be dropping out of the northwest, it will not have a lot of moisture with it, and it is not particularly strong either. There is little low-level cold air with the feature, but falling heights and some precipitation will cool the column enough to support snow, even in most low-elevation areas, although it could start as rain or a rain/snow mix in the central and southern Champlain Valley. Eastern Ontario and northwestern New York will receive little or no precipitation with this feature as it digs farther east. The greatest snow totals will be in the northern Green and White Mountains, the eastern Townships of Quebec, and in Maine, where locally up to 2” (5 cm) is possible.

Source: TropicalTidbits

As the feature pulls away on Tuesday, upper-level ridging rapidly builds back into the eastern U.S. and intensifies, leading to mostly dry and unseasonably mild weather for Wednesday and Thursday. There could be a few showers in mountainous areas and north of the U.S./Canada border on Wednesday, but it will otherwise just be mostly cloudy with modest warm advection. 

Source: TropicalTidbits

The intensifying trough/ridge couplet in the western/eastern U.S. will steer two storms coming out of the southern Rockies to the northeast. The first system will head into Quebec and begin to weaken, leaving very little precipitation in our region, even along its cold front that will slow down and stall. However, there is still a significant model and ensemble spread in the speed and strength of the second system. The most likely scenario is for it to follow shortly behind the first system, strengthen, and get pulled quickly to the northeast by another shortwave over south-central Canada into Quebec. This will lead to everywhere in our region to become especially warm Thursday into early Friday, with lower elevations of Vermont, New Hampshire, and southern Maine possibly reaching 60F (16C) and potentially breaking daily record highs. However, there is still a chance that the second system is a little weaker and delayed until after the first system’s cold front passes through northern New England. In this case, the shortwave over south-central Canada would already have gone too far east to sling the storm to the north too much, and the storm would track far enough south to avoid the major warmup in northern New England and even produce snow north of the U.S./Canada border. The storm could also be more elongated which would lead to a zone of lighter rain changing to snow. Even then though, the lower elevations from Vermont to southern Maine will lose all or almost all of the snow cover.

Source: MétéoCentre and TropicalTidbits

Regardless of how the second system evolves, it will turn colder afterwards, though it will be not as cold and long-lasting as earlier modeled. Instead, low pressure will move into western Canada again, and the southeast U.S. ridge will return by Monday, quickly moving the cold air back into central Quebec. For now, it looks drier and not as warm as this week’s warmup, with limited flow out of the Gulf of Mexico and lack of a strong, consolidated storm ejecting from the Rockies. After this, the details become really uncertain, with another warmup likely but it could either last several days with more rain or be brief and followed by much colder air and a snow-producing system.

Source: TropicalTidbits

Ensembles in the long-range indicate cold surface high pressure and low upper-level heights gradually dominating central and eastern Canada by around February 22, while the southeast U.S. ridge remains resilient though beaten down somewhat. This corresponds to the MJO weakening and moving out of the warm phases 5 and 6 and into cooler phases 7 and 8. This allows for colder air to filter into northern New England and an active storm track through our region or just to the south, which would provide plenty of snow and ice opportunities, especially in northern areas, but also still the risk of rain, especially in southern areas. Once again, latitude will likely be crucial in getting snowfall, with southern Vermont and southern New Hampshire perhaps losing out again while Quebec and northern Maine get a lot of snow, just like how the winter has been so far.

Source: TropicalTidbits

Source: Climate Prediction Center

A major sudden stratospheric warming event is also about to occur, but whether its effects can propagate downwards into the mid-troposphere is still uncertain, and if it does, the effects on our weather will not be felt until the end of February or beginning of March at the earliest. However, such events, if they propagate downwards to the mid-troposphere, tend to, though not always, lead to more Greenland blocking and below-average temperatures in the eastern U.S. Both of these would be conducive for snowstorms in New England and could lead to a delayed spring, despite the warm winter we have had and the increasing sun angle in March.

Source: Tomer Burg and Butler et al. 2017

Source: StratObserve