Cold Sunday with snow showers along and NW of Appalachians; milder most of this week with rain on Thursday except wintry mix onset NW of St. Lawrence River; snow chances on Friday/Saturday and following Monday/Tuesday and still somewhat wintry through start of April

Plain-language summary:

After a cold day on Sunday with snow showers along and northwest of the Appalachians, it quickly turns milder on Monday. A weakening cold front will stall in over the region on Tuesday, possibly bringing a bit of snow or rain. A storm will bring rain late Wednesday night into Thursday, except a brief period of snow in the Laurentians and possibly a brief period of freezing rain just northwest of the St. Lawrence River. Another storm could bring snow late Friday into Saturday, but it could miss to the south or just not be cold enough to snow. Another storm could also bring snow the following Monday into Tuesday, but uncertainty is even higher for that storm. More potent cold for late March likely follows, leading to a chilly end of March and perhaps more snow chances through early April.

 

Meteorological discussion:

A deep cold air mass is in place over the region today. However, it is somewhat modified due to it passing through the Northern Plains and the Great Lakes first. This passage both warmed and moistened the low-levels, and along with the strengthening March sun, is leading to steep low-level lapse rates and widespread convective snow shower activity along and northwest of the Appalachians. The snow showers are the strongest over the higher terrain, as is typical in this type of setup, where up to 2-4” (5-10 cm) could accumulate, while lower elevations will struggle to reach a half inch (1 cm) with intermittent sunshine. Areas to the southeast of the Appalachians will remain dry and slightly warmer due to downsloping. The cold air will be short-lived though, as another system will scour out most of the cold air by Monday, though the system’s cold front will temporarily push south into northern New York and Northern New England by Tuesday before stalling, perhaps producing light snow or rain along it.

Source: Aviation Weather Center

Source: PivotalWeather

The southeast U.S. ridge is making an unexpected comeback this week, accompanied by a trough digging into the western U.S. This all-too-familiar setup will lead to an initial storm cutting into the Great Lakes and eventually into Quebec Wednesday into Thursday, and with the cold air mass already scoured out ahead of it, precipitation will be all rain virtually everywhere except possibly the Laurentians north of the St. Lawrence River. There might be a brief period of freezing rain Wednesday nigh into Thursday morning just northwest of the St. Lawrence River due to channeling of low-level cold air from the northeast, but it will quickly change to rain later on Thursday. However, the warm sector will be pinched off and never really arrive into Northern New England. The details get murky afterward, with the possibility of another storm tracking farther south by Saturday which would be more likely to produce snow with modest cold air behind the first storm, though temperatures would still be marginal for most. However, it could all get consolidated into the warmer storm system earlier in the week, leading to little or no energy leftover to produce a second storm, in which case it will just turn cooler and drier.

Source: TropicalTidbits

Another storm will be ejecting out of the southern or central Rockies next weekend, move east or northeastward, and likely will affect our region by the following Monday or Tuesday. Such a storm will likely pull substantial Gulf of Mexico and later Atlantic moisture, so it could be a big one. However, a range of possibilities ranging from a miss to the south to a snowstorm to a storm cutting into Quebec producing mainly rain is still possible. It does appear that more potent cold for late March will follow behind that storm, leading to a chilly end of March and perhaps more snow chances through early April. While predictions of substantial cold have repeatedly failed this past winter, this pattern will be aided by the relatively plentiful supply cold air in North America, still deep snowpack in many places from the Nor’easter earlier this week, and some Greenland blocking accompanied by a slightly -NAO. The Gulf of Mexico ridge could still be a factor though, like it was throughout the winter.

Source: TropicalTidbits

Source: TropicalTidbits

Source: NOHRSC and Climate Prediction Center