Wednesday night into 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 for southern and central New England. The northern tier will be colder as the system passes, resulting in mainly snow showers and light accumulations.
Precipitation will likely break out in the pre-dawn hours across southern New England before steadily moving north and east through the morning. By morning commute time, rain and snow showers will be ongoing across much of New England outside of eastern Maine. Interior northern New England will likely be seeing snow at this time with southern and coastal New England having switched to rain. The rain/snow line will steadily push northward as temperatures begin to climb from morning lows.
Below: HRRR showing potential weather in the pre-dawn hours Thursday (1st image) and just after sunrise (2nd image):
As milder air advects into New England behind the warm front during the day Thursday, aiding in the transition from snow to rain well into northern New England. This may take until the afternoon to occur in the New Hampshire Lakes Region and points north.
Once the milder air advects into the region, a dry slot will help scour out precipitation, so while a changeover to rain is expected, it may be lighter and more scattered in nature versus the morning snow. Throughout the afternoon and into the evening, scattered showers (rain for most) will continue to work through the region. Precipitation will gradually diminish heading into Thursday night.
Below: HRRR showing potential weather around late-afternoon Thursday:
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.
The overall setup isn't conducive to a widespread wintry mix. For most, it will either be snowing, raining or a mixture of both. A brief period of freezing rain/drizzle may be possible during the transition, but an extended period of a wintry mix (sleet/freezing rain) is unlikely at this time.
For interior northern New England, precipitation rates will be steadiest during the morning to early afternoon, before the changeover occurs. Warmer air will be quickly moving in while the band of heaviest precipitation occurs during this time. This will be a race between the steadiest snowfall and the advancing mild air. A band of moderate snowfall will be possible just north of the rain/snow line during this race.
This continues to look like it will set up in a zone from the New Hampshire Lakes Region to the White Mountains and into the western Maine foothills. These areas will have the best shot at 3-5 inches, though we're thinking most communities will still likely see less than 5 inches (3-4 inches is the more likely high point for most communities). Lesser amounts will be seen north and east of this zone with less moisture to work with and areas south will see less as rain showers take over.
As for the wet side of the storm, the steadiest and more widespread rainfall looks to occur through the morning hours for southern New England before transitioning to off and on showers through the afternoon and evening. A widespread 0.10-0.25 inches of rain is expected. Some areas that see persistent and consistent rainfall with little to no snow may try to push to a half an inch.
The system's cold front will get pulled across New England Thursday night into Friday morning. This will result in temperatures dropping a notch for Friday along with a period of gusty winds during the day. Shallow cold air advection is expected, so the day won't be dramatically colder. This shallow advection will likely set up an inversion, allowing for a band of snow to develop across the northern tier Friday morning. This band will dissipate quickly moving east and south. The northern Greens could see an additional couple inches.
Below: RGEM showing potential weather around sunrise Friday:
On Saturday, an Alberta clipper will zip through New England, bringing another quick round of rain and snow showers. This appears to be a pretty standard Alberta clipper, which will move through at a rapid pace, bringing a round of light snow to the north of the track and a mix of rain and snow to the south of it. This may behave like Thursday's storm where the rain/snow line starts off in southern New England and rises northward during the day Saturday. The track will determine the northern extent of the rain/snow line in New England.
A very sharp temperature gradient will be possible on Saturday with a wide range of temperatures across the region. Areas south of the track will get into the system's warm sector, allowing temperatures to spike into the mid 40s to low 50s. Areas well north of the track will get locked into colder air. Subtle changes in the track could have a big impact on temperatures, especially in a zone from the Mass Pike to the New Hampshire Lakes Region.
Below: Euro showing temperature departure from average Saturday morning:
This system currently looks less developed than the Thursday one, so precipitation isn't expected to be heavy. Combine this with the quick-moving nature of the system, and total accumulations of both snow and rain will be on the light side once again. Northern and eastern Maine will likely be in the bull's eye for the most with this one.
Alberta clippers often swing the door wide open for Arctic air to enter New England as they depart, and this one is no exception. Cold and breezy conditions will return for a two day bout for Sunday and Monday. Areas of New England that get into the warm sector on Saturday could see highs a good 15-20° colder on Sunday.
Temperatures currently look to moderate back toward average by Tuesday of next week. Cold high pressure will be in charge during this time with the next potential storm system to watch coming around midweek next week.
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