10 PM Thursday Update: It's interesting...history for the forecast storm track dictates a foot of snow should fall in Southern Maine, but nearly all forecast solutions had a sharp cutoff of snow in Maine. Just as we were going on-air for the 9 PM show, a few pieces of evening data came in showing lots of precipitation for coastal Maine...though I often shy away from knee-jerk reactions (because they're usually wrong), in this case, that was all I needed to see - when I know history favors a solution, anyway, I really just need one decent piece of evidence to lean that way. As a result, I upgraded all of Central and Southern Maine's accumulations. I've reflected that in the maps below.
I began airing our more detailed, updated accumulation map in Broadside with Jim Braude at 6 PM Thursday evening, looking out to the upcoming weekend snow. Of course, if you read frequently, you know in tricky events I like to wait until within 24 hours of snow commencing, which would be Friday afternoon for this storm - but with this storm we have one area that's very tricky, but a larger area that brings higher certainty.
The interior of New England is quite likely to maintain enough cold air for an all snow event Saturday afternoon through Sunday morning, and this area is where increased forecast certainty is found. Meanwhile, an onshore wind and the absence of hearty, arctic air, means a coastal front will develop and drift in off the ocean, setting up a rain/snow line inland of the coast - this is where the uncertainty and tricky forecasting comes into play. On the warm side of the coastal front, a mostly rain event will occur, with perhaps a burst of some wet snow early, then rain Saturday night into Sunday morning, then perhaps a flip back to snow at the end of the storm. On the cold side of the coastal front, heavy wet snow will fall heavily, and will be enhanced by the clash of air, setting up steeply increasing amounts. At this point, given the lack of strong cold air, it seems rather likely the coastal front will penetrate rather far inland to Southeast Massachusetts, and even along the North Shore, but will have trouble sailing too much farther inland than Route 495, particularly north of the Massachusetts Turnpike. Additionally, warm air will erode the cold in much of far Southern New England, and some of that warmth will likely ride over the top of lingering cold in interior Massachusetts to create sleet along and just north of the Connecticut border for a time Saturday night, limiting snowfall amounts a bit in these locales. So, as you view the map below, keep in mind that there is still some flexibility on placement of the snowfall gradients (drop from high to low amounts).
As for the other details of the storm, no big changes, but the recap is:
- Snow begins early afternoon in Connecticut, mid to late afternoon in most of the rest of Southern New England, perhaps as late as early evening in Southern NH, then fills in northeast Saturday night.
- Snow will be heavy and wet in consistency. This means scattered power outages will occur inland...particularly where greater than 5" of snow is forecast.
- Onshore wind increases overnight Saturday night, gusting as high as 50 mph on eastern coasts of Massachusetts into Sunday morning
- Strong wind gusts Saturday night into Sunday morning contribute to building seas - 10-15 feet by Sunday morning, up to 20 feet by Sunday afternoon offshore
- Sunday morning's high tide is not exceptionally high, but depending upon how strong the storm strengthens, some minor coastal flooding is possible mid-morning
- As the storm pulls away, even those areas that see mostly rain may briefly snap to snow, explaining the forecast accumulation in these areas of Southeast New England.
Eastern Massachusetts Early Estimate (please keep in mind nature has some variability - allow for about an inch either side of forecast values):
Southern New England Early Estimate (please keep in mind nature has some variability - allow for about an inch either side of forecast values):
Northern New England Early Estimate (please keep in mind nature has some variability - allow for about an inch either side of forecast values):