March 11th 2017 605pm entry:
Very cold air mass overhead the Northeastern US tonight. temperatures for Sunday morning lows are around 10-12F over the Cape. Forecasted temperatures won't break 25 the next two days Sunday and Monday. This arctic air mass will be the reason we can expect a snowstorm to occur some time Monday night through Wednesday morning depending upon if the storm slows down at all, right now the 12z and 18z runs today show a progressive but easterly track with less phasing, although I don't think this is about a less of a phase. While common knowledge dictates that the stronger the phase the further west the storm tracks is correct most of the time, the 18z GFS and NAM are both east of the 12z runs positions, and therefore show a faster transfer of energy between the clipper (primary) low and the coastal storm that takes over earlier on the latest guidance. Given nature of the H5 trough, this should allow the coastal storm to intensify rapidly and be in the lower 970mb range, rather than the higher 988mb range the GFS has. Therefore winds should gust between 70-90mph, 70mph if the GFS is right or 90mph if the stronger solutions are correct. Remember the faster the transfer of energy between the primary OH Valley low and the coastal low off the coast of SC occurs, then the further eastward it will travel, I don't expect a far east track, but one down the middle of today's guidance, over the benchmark, east of ACK and CHH of around 970-980mb low pressure center producing a few feet of snow from DC to BOS with NYC to BOS receiving the mega amount of snowfall of around 24-30" of snow. Coastal New England including Cape Cod should remain all snow and receive up to 34" of snow. Those are my thoughts right now, subject to change.