New England’s first extended thaw in a while is now underway. While this occurs, some weak systems will be sprinkled in as the pattern that’s helping to bring the milder weather is also producing an active pattern. With the northern and southern streams generally out of sync, New England will be getting energy from the moisture-starved northern stream. This will preclude any big storms.
The peak of the mild air will arrive this afternoon and will generally remain in place through Thursday. Today may end up being the warmest day for much of New England. Wednesday will be the driest day across New England, but a cold front will drop into northern areas in the morning. This front will weaken and fall apart as it works southward, likely not making it past Massachusetts' northern border. It may produce a period of increased clouds and an elevated breeze. Temperatures should be similar to Tuesday, but maybe a notch cooler.
Thursday will remain elevated in the temperature department, though higher elevations of northern New England and northern Maine will likely get held cooler due to the incoming system (discussed later). New England's snowpack will be shrinking this week, especially in southern New England, but low dew points will keep this as a rather slow process for most. Eastern areas of southern New England may erase their snowpack by Friday. With factors working for and against snowmelt in some places, it will be interesting to see where it stands by this weekend across the region.
Below: Current snow depth as of Tuesday morning:
As for the disturbances sprinkled throughout this week, there are three main ones to watch; all of which are on the weaker and low-impact side. The first comes this afternoon and evening as a weak trough crosses to the north of New England. At the same time, a southern stream system will pass well offshore of New England. While these two systems will remain separated (the streams are out of sync), it will bring a period of unsettled weather.
Without the assistance of the southern stream, this system will produce a period of light to steady rain and snow showers. While guidance was split on how widespread snow showers would be across northern areas, it looks like it will be confined to higher elevations with more by way of rainfall in the valleys. Light accumulations of both rain and snow is expected, with a quarter inch or less of rain and an inch or less of snow. Showers will be more numerous across northern New England and gradually diminish in coverage moving southward.
Below: FV3 showing expected weather this evening:
Heading later in the week, the flow starts to become more amplified (versus the zonal flow at the week's start) with a ridge building in the west and a trough digging into the east. This will allow for a more organized (albeit still weaker) system to cross New England on Thursday. A frontal system will eject out of the Great Lakes and likely track across the New England-Canadian border. This track will lift its warm front across New England during the day. This will result in continued mild conditions.
With the system likely arriving in the predawn hours, when temperatures are lowest, it may start off as snow where overnight temperatures drop below freezing. The rain/snow line will steadily move north and east through the day, changing to a mix of rain and snow. Overall, thermal profiles appear to be marginal Thursday morning for most of New England. This could support snow or a mix before a quick changeover to rain for areas north of the Mass Pike. Overall, the system has trended a bit colder over the past 24 hours.
While this system is more organized and has more moisture to work with, it won't be loaded. The current precipitation forecast continues to show a quarter inch or less. This would result in total rainfall less than a half inch and total snowfall around 1-3 inches where snow continues into the day Thursday.
A band of moderate snowfall will be possible just north of the rain/snow line Thursday morning. This will be the main trigger for a few inches of snow to fall. As of now, this bull's eye is being shown over central New Hampshire, where there is up to a 70% chance of at least 2 inches of snow.
Below: Current probability of at least 2 inches of snow Wednesday night to Thursday night:
Precipitation looks to break out in the pre-dawn hours Thursday before steadily sliding northeast through the morning. By midday, much of the region will likely be seeing either rain or snow showers. Precipitation will likely be steadiest in the morning before gradually winding down from west to east in the afternoon. Much of Maine may see their steadiest precipitation toward the afternoon and evening, being the farthest east.
Below: RGEM showing potential weather late morning Thursday (1st image) and mid-afternoon Thursday (2nd image):
Finally, a clipper system will swing through the region Saturday into Saturday night. There remains a large spread in track, which will ultimately determine a rain/snow line. The farther south the system tracks, the farther south snowfall would occur in the region. The farther north it tracks, the farther north a southerly flow and deeper mild air would push, allowing for more rain showers.
Naturally, the farther north you go in New England, the better the chance to see more by way of snow showers over rain showers. Regardless of where a rain/snow line sets up, this storm hardly looks menacing and will likely result in another round of light accumulations of both rain and snow.
There may be a large temperature gradient set up across the region on Saturday. Overall, temperature profiles are uncertain for Saturday as it will heavily rely on the storm's final track. With that said, greater than usual adjustments to high temperatures Saturday could occur (for warmer or colder conditions).
Strong cold air advection is expected behind this system, which is not a surprise as clipper systems often see a blast of arctic air behind them. Sunday will likely turn sharply colder with temperatures remaining low into Monday. A quick moderation back to milder conditions (or at least seasonable) will be possible by the middle of next week.
Below: Temperature departure from average Sunday afternoon (March 2):
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