More to Come...
This three part storm has begun and we are almost through the first stage. A burst of snow is moving through Eastern MA right now and generally putting down 1-3". Accumulation has been very interesting and difficult on the pavement especially...much easier on the grass and cartops. So far most of the roads have held up well, some of the less traveled ones have become snow covered and slippery. I don't see much changing through for the remainder of the night as there are several limiting factors for snow accumulation...soil temp, surface temp, intensity of snow to name a few. All will be marginal until tomorrow morning when phase two gets underway.
The parent upper level storm system will be swirling in from the Ohio Valley, this will induce surface low pressure cyclogenesis south of New England tomorrow morning giving us our second burst of snow and rain. By then, warmer air will have worked northward changing snow to rain south of Boston. But most areas will be snow and because of the timing (pre-sunrise) and expected intensity, snow will be much more efficient at accumulating and there will be a window of about 4 hours early tomorrow morning for 1" per hour snow rates. After 8-9AM, with the sun up, surface temps will begin to rise back above freezing and even though snow will be falling, it won't accumulate that well. The surface low will spin off to our east by afternoon and our wind direction will shift and take on a more northerly component, this will suck down surface cold air from Northern NE, setting the stage for the third and final wave of snow.
This wave will come in for the Thursday evening commute and will be charged by the upper level storm system creating good lift once again. That along with the setting sun and colder surface air bleeding sown from the north, should produce a final efficient accumulating burst and a rain/snow line that crashes back to the Cape.
All told, these three waves and nearly 36 hour storm will leave behind 3-6" of snow for Boston out through 128...6-10" 128 to the west and north with the higher amounts falling in elevated areas...mountains of Central and Northern NE picking up around a foot or more...1-3" in SE Mass (most of that falling right now). The amounts will be largely dependent on elevation and distance from the coastline.
