Concern for heavy snowfall continues to revolve around the
potential phasing of northern and southern stream energy somewhere
along the east coast during Saturday. Guidance continues to
feature a variety of solutions in both the amount of phasing, as
well as when this will occur, not to mention the resultant surface
low track. There has been wide variability leading to lowered
confidence in the forecast, and a trend towards the ensemble means
remains prudent.
That leaves a surface low which will lift northeast through
Pennsylvania before transferring to secondary low development
south of Long Island. If northern/southern stream phasing can
occur early on Saturday, this low may track into the Gulf of
Maine, but the trend has been for a more suppressed solution as
the dynamics eject east quickly, allowing the surface low to
remain weak and push off to the east as well. Initially the
thermals will only support rain due to a warm column, with the
exception being northern New England, but as the low pulls away
cold air will wrap back towards the coast causing a p-type
transition from rain to snow. The amount of precipitation
available once the column cools remains in question, and at this
time most of the snowfall is forecast to be light to moderate,
with the highest amounts confined to the terrain. WPC
probabilities for 6 inches are 30-50% in the Adirondacks, Greens,
and Whites, with lesser amounts further to the south and at lower
elevation.