Unseasonably mild through Wednesday; possible snow or wintry mix for central/eastern New England late Thursday; cooler Friday, and possible slow-moving storm next weekend into following Monday; colder pattern likely for mid-late March

Plain-language summary:

 

After yesterday’s widespread light rain, we are now left in an unseasonably warm air mass through Wednesday, with the warmth peaking on Monday. Daytime highs will be unseasonably warm even with only partial sunshine, and nighttime lows will be even more unseasonably warm due to the clouds and unseasonable humidity. It turns cooler but still a bit mild starting on Thursday, with potential snow or wintry mix in central/eastern New England late Thursday into Thursday night. After a likely dry day on Friday for most, a slow-moving storm could bring widespread precipitation, perhaps as elevation-sensitive snowfall, for next weekend into the following Monday. It likely turns mild for a few days of the following week before turning chilly by late mid-late March standards, perhaps allowing for a final snowstorm or two of the otherwise dud of a winter.

Meteorological discussion:

 

With yesterday’s widespread light rain gone, we are now left with an unseasonably warm and moist airmass, with pronounced troughing in western North America and ridging in eastern North America (-PNA pattern). The warmth will be enhanced by the unseasonable lack of snow cover almost everywhere except the highest elevations, with daytime highs reaching above 60F (16C) in the southern St. Lawrence Valley of northwestern New York on Monday, even with only partly sunny skies. It will be cooler to the east due to more clouds and moderation from the still cool western Atlantic waters with the southerly flow. Lows will be exceptionally warm due to the clouds and unseasonable humidity. A weak storm coming up the U.S. East Coast will bring light rain to central and eastern New England on Tuesday, and increased clouds elsewhere, which means it will not be as warm as on Monday. The warm spell is less impressive than it looked earlier due to this increased clouds and storminess, though it will still be much warmer than average.

Source: TropicalTidbits

 

A cold front passes through on Wednesday with rain for a few hours, but nothing too heavy is expected. The air will still be a bit mild behind the cold front, but significantly cooler, and just cold enough for wintry precipitation should a relatively weak storm from the Deep South of the United States come up the East Coast and affect central and eastern New England by Thursday afternoon. The high pressure to the north will continuously feed in cooler air from the north, and combined with ascent and precipitation cooling down the column, will likely lead to a narrow area of snow on the northern side of the storm, but the location of the snow area is uncertain now. Alternatively, if the storm is too weak and too far south, everyone could just remain dry. The storm could also slow down and throw precipitation into Maine into early Friday. A lot of this is dependent on the timing of the storm relative to the previous cold front. The longer it waits for the cold front to pass and high pressure to build in, the more likely the storm will be able to come far enough north to throw precipitation into our area as snow or a wintry mix.

Source: TropicalTidbits

Source: TropicalTidbits

 

 

As the potential East Coast storm moves out by Friday, a larger, slower-moving storm will emerge from the Plains and into the Midwest U.S. and Ohio Valley or possibly into the Great Lakes. The storm will move slowly due to high-latitude blocking developing (-NAO) and some ridging to the north. By Sunday, the storm will likely have transferred to the East Coast and possibly form a Nor'easter, and could bring widespread precipitation in our region, though amounts and precipitation types are uncertain. Then, it could strengthen more due to the natural temperature gradient just north of the Gulf Stream that Nor’easters often take advantage of, leading to a period of heavier precipitation, though this will likely not be the classic Nor’easter. The air behind the earlier potential East Coast storm is not that cold, so temperatures will likely be above freezing before the storm arrives, and we will have to rely on ascent and precipitation cooling down the column, as well as the storm transferring to the East Coast and cutting off any surge of warm air from the south, to get snow. This type of setup tends to lead to snowfall being highly elevation-sensitive. It will be a broad, slow-moving storm system with widespread precipitation (perhaps light or intermittent at times) lasting for 1-2 days, with areas of terrain enhancement and shadowing depending on the exact wind direction. For now, anything from a mostly rain scenario with the primary low pressure cutting too far to the northwest to a widespread storm if the storm takes the right track to just dry weather if the storm is suppressed to the south and weaker is possible.

 

Source: TropicalTidbits

As high-latitude blocking (-NAO) and -AO becomes more dominant starting later next week, some ridging will finally develop in western North America (slightly +PNA) a bit later in mid-March, which will help facilitate troughing in eastern North America then. Before that, one more trough entering the western U.S. next weekend or early the following week could still lead to some ridging and warmth for a few days after next weekend’s potential storm. Given the unseasonable widespread lack of snow cover, any cold air from the north will be modified as it heads into our region, and climatology and increasing March sun angle dictates that bitterly cold air is extremely unlikely. However, temperatures might finally go below average, which would still be cold enough for snow in our region if any storm takes the right track. If we can get the trough axis at the right location and pieces from the polar and subtropical jets to finally interact and phase well, we could get the Nor’easter that has been elusive all winter long. Any outlook that far out is not with high confidence, especially given that this pattern was initially forecasted for late February and completely failed to occur, but this pattern for now is expected to last into early April, perhaps giving a final gasp of an otherwise dud of a winter.

 

Source: TropicalTidbits

 

 

Source: Climate Prediction Center