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Alberta Clipper System to Bring Northern New England Some Snow

A robust Alberta Clipper system will pass to the north of New England on Wednesday. This system will likely form a secondary low along its triple point (where the warm front, cold front and occluded front meet). This will allow snowfall rates to become enhanced, especially for the White Mountains and eastern Maine.



The system will lift its warm front into New England during the day on Wednesday. This will result in the warmest day of the week for most of New England. This front will also provide the lift for some widely scattered snow/rain showers beginning Wednesday morning.


Starting in the afternoon, the system's cold front will be dragged across New England, leading to increased snow showers, with some snow squall potential across northern areas, ahead of the front. Southern and central New England will mainly see a few rain (or mixed) showers in the afternoon and evening.


Euro showing expected weather Wednesday afternoon:



As we head toward Wednesday evening, the system's secondary low may strengthen rapidly. This will allow scattered snow showers to fill in across northern New Hampshire and Maine. As always in this sort of setup, the timing and track of the secondary low (along with how fast it actually strengthens) will play a large role in how much snow falls and where it falls. The strengthening of the system will help flip mixing in Maine over to snow.


Euro showing expected weather overnight Wednesday to Thursday:


There is a decent amount of uncertainty surrounding this system, especially given the close time frame. There will be snow showers from Wednesday afternoon through Thursday morning. The question is how quickly the secondary low will strengthen to help fill in the snow showers. This secondary low will help produce banding.


As of now, it appears that a wide swatch of 3-6 inches will be possible from northern New Hampshire through northern Maine with amounts on the lower end in the valleys. There's some guidance going up near a foot along the Canadian border, but that's really pushing it. The air mass the storm will move into will be dry, so the storm will need to strengthen in order to overcome that dry air. This air may eat away at snow totals initially.


Snow showers will likely continue to wrap around the system into northern and eastern Maine throughout much of the day Thursday. Snowfall amounts will likely vary from town to town as some areas will likely see more numerous snow showers than others.


Euro showing potential weather Thursday afternoon:


With highs climbing above freezing for most on Wednesday, the snow will have a hard time sticking initially as well. For these reasons, we're leaning toward the lower side of snowfall guidance. The Green Mountains will see generally less given the secondary low will form too far to the east, so they will just get snow showers and maybe some squalls Wednesday morning into the afternoon.




Winter weather advisories may be posted later today for northern New Hampshire and Maine. Winds will also pick up as the system intensifies. This will lead to blowing snow as winds gust up to 40mph. Despite the lower snowfall amounts expected, this will lead to reduced visibility and potential travel impacts.


WPC probability of snowfall accumulating at least 6 inches by Thursday afternoon:


Looking ahead to the potential storm this weekend, it is starting to look more likely to be a typical spring snowstorm with snow at higher elevations and northern areas with mainly rain south and lower elevations. As one would expect at this time frame, there is a large spread in where the coastal system will track. The storm's track will be the determining factor in who gets what.


With an area of high pressure to the north potentially feeding colder air into the system and the potential for phasing between northern and southern stream energy pieces, there is plenty that needs to be worked out, we'll be watching the trends closely over the next 36 hours to see how things evolve among the models.



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