I'm always first to tell my viewers and readers that, outside of 24 hours, any snow accumulation is going to be less likely to verify. Often, as a result, I don't issue exact forecasts much outside of this window...unless there's a decent level of predictability. For this upcoming weekend, predictability is, as of this writing, approximately 70%. It is certain that a developing storm will pass south of New England - meaning almost all of Southern New England will be cold enough for a snow event, rather than any mix. Cape Cod will be the one possible exception to this - particularly the eastern half of the Cape, where the likelihood of an all snow event is only about 10% (that increases to a 50/50 shot on the western Cape). So...the big question is: how much will fall from the sky? The answer to that question hinges almost solely on how quickly the storm passing to our south develops, and the possibilities range from a quick development allowing for snow to spread north very effectively, to a slower development that doesn't allow the snow shield to expand north until the storm center is nearly past our longitude. My forecast favors a solution that is weighted somewhat toward the quicker side, meaning an expansion of the snow shield over Eastern New York and New England. My most important task Friday will be to determine if this solution is still the most likely, and by Friday evening on NECN, we'll be within that 24 hour window, and this will either add great support to the forecast, or demand an overhaul. That said, I hate changing a forecast and would rather put nothing out until there's a decent chance of verification, so the issuance of this early estimate should be evidence of the aforementioned 70% predictability.
Arrival time is Saturday mid-afternoon. Exit time is very early morning Sunday.
As always, click to enlarge the image.