With the darkest quarter of the year (solar winter) behind us, low-level temperatures borderline, and time of day somewhat relevant to the snowfall accumulation forecast, it’s time to declare this the first storm of late winter. This may be good or bad news depending on your perspective, but all of us should remember that late winter can last quite a long time here in northern New England and even early spring (whenever we get to that) can be snowy.
The storm arriving today will be of the messy and mostly unpleasant sort, both for those of us forecasting it and those of you experiencing it.
Southerly winds will continue to push warmer air into the region this morning, leading to initially chilly temps rising quickly towards the mid 20s up north and mid 30s along the Midcoast. Any glimpses of the sun this morning will be short-lived as clouds advance from the west.
Precipitation will arrive from the south starting around noon but it’s not clear exactly what form it will take. Temperatures west of I-95 will be cold enough for frozen something, but there’s likely to be too much dry air aloft to support much snow. So expect the event to start off with a period of “snizzle” i.e. some snow and some freezing drizzle. It won’t accumulate much, but it will be quite slippery for those surfaces that don’t get a dusting of sand this morning.
Proper snow will develop from southwest to northeast this evening as better moisture and lift move into place. Most spots SE of I-93/NH101/I-95 in NH and I-95/I-295/US1 in ME will start this event with plain old rain thanks to onshore winds. As per usual, my money is on the surface cold air hanging tough in the foothills and mountains especially given our relatively deep/fresh snowpack. So watch for slick spots away from the coast during the evening commute today but overall no major issues are expected.
Model guidance is rather optimistic, I believe too much so, regarding the ability of above-freezing air to surge inland overnight. I think the freezing line will be able to push towards Sebago Lake/Lewison/Augusta, but better lift and heavier precipitation will likely keep precip types leaning towards snow. By tomorrow morning, the rising sun may push the 32F line up towards the mountains while cooling aloft pushes the rain/snow line closer to the coast. Yes you can get snow even with surface temps above freezing if it’s cold enough aloft and the near-surface warmth is very shallow. That said, warmer temperatures near the ground will support a much wetter snow than our past couple storms which means we’ll open the door to some power outage concerns especially inland.
Now for the age-old question: how much snow do I think will fall?
Here’s my current thinking given plenty of uncertainty both in temperature profiles but also how much precipitation will fall period. There’s still some model guidance that keeps the steadiest/heaviest stuff to our east which is one thing to watch out for in terms of bust potential.
The jackpot will, as is so often the case, be up in the mountains. Most of the ski areas can look forward to a solid 4-8″ and I wouldn’t be surprised if Sugarloaf and Saddleback especially can challenge the higher end of that. This will be a slightly wetter snow, especially at the onset, but with an already-deep base up there the skiing will be good regardless.
Most of the Maine foothills should come in around 4″ with the tops of the hills doing better than the valleys. Most of the I-95 corridor is looking at about 2″ of heavy wet snow while the coast is likely limited to a dusting or an inch at best as colder air wraps into the back of the system tomorrow.
As a general rule, 4-6″ is the threshold for power outage concerns with this type of heavy/wet snow, so be prepared for that if you’re up in the inner foothills/mountains.
The storm will depart from west to east tomorrow afternoon.