Although there is still a considerable amount of uncertainty in the scenario for Friday night, my overall thought on the evolution and track of the storm has not changed - it seems to me that we should see accumulating snow reaching as far north as Southern and perhaps Central Vermont, New Hampshire and Southern Maine. Having said that, I humbly acknowledge - given the combination of lacking agreement and consistency in computer guidance, and lack of agreement between my thoughts and the mean of guidance as of this writing - a forecast overhaul may be necessary. With that said...
Late Tuesday evening, I posted my reasoning, most notably the merger of two energetic disturbances near New England that would allow for a track close enough to the South Coast to lift snow across much of the area. As of this Wednesday evening post, I see no major change to the overall setup, though I do have necessary, meaningful adjustments and additional details. Potential Friday overnight map has been updated, below.
- Storm center likely to pass over or extremely close to (last night I opined over or just slightly inside of) Southern New England's snowstorm "benchmark" of 40° north latitude/70° west longitude. This is very close to last night's projection, and I don't expect it to change. Rather, I expect this solution takes the lead and computer guidance comes in line with this solution to back it up.
- Typically, such a track would lock in substantial snowfall for Southern New England - that may be the case for some of us, but this is a different storm...so most of us will not see the usual "jackpot" scenario such a track would bring.
- Total snowfall amounts will depend on several factors - first and most important is the rate of intensification. As mentioned last night, I believe the merger of two disturbances, combined with the temperature difference of very cold air with warmer ocean water, will afford the opportunity for quick storm strengthening. (Technical: Essentially, we have a rare and wondrous situation of an arctic shortwave that negatively tilts in a positively tilted longwave pattern regime. That basically means a situation where the storm does have a window to intensify quickly, but is destined to remain very progressive due to the longwave positive tilt)
- Given cold air in place, snow will be very light and fluffy in consistency for most - perhaps excepting Cape Cod, depending upon exact track. This doesn't always mean the most efficiently accumulating snow (believe it or not, too cold limits snow accumulation), but it does mean most of us see lightweight snow, and many will find at least some enhancement to accumulation rates.
- The atmosphere favors a VERY quickly moving storm - so, regardless of how quickly it intensifies, or how fluffy the snow is, the bottom line is it keeps moving so you're not getting a blockbuster here. It's in Friday around or after dark, and out early Saturday morning.
- So...how much snow? Tuesday night I opined 6"-12" was not outside the realm of possibility for this system somewhere in Southern New England. Those of you who follow me often, know that's a huge range compared to what I normally give. The reason for this is that - with limited computer support - finer details like total precipitation is rather difficult to fine tune, when the broad brush still isn't where you need it. That said, based on reasonable track adjustments, I think the upper end of that range probably will not verify, but a 6" or 8"...and if this really can crank up, a 10"...certainly may be achieved in localized highest amounts, with more widespread two or three inches more common...but again...we'll see.
Potential Friday overnight map - keep in mind that amounts of snow TBD, generally heavier the closer to the storm track one is: