While we are confident in a plowable snow across most of southern
New England, the uncertainty exists on whether or not higher amounts
advertised by certain models will be realized. Also, the northwest
extent of the heavier amounts is also uncertain. There is a battle
amongst a lot of the global vs. high resolution model guidance. The
tendency is for a lot of the high resolution data to be heavier with
the snow amounts and also further northwest compared to the global
models. It is quite evident even comparing the 3 KM to 12 KM NAM
model.
Given the differences we somewhat blended the guidance together.
While we think some of the high resolution guidance may be too heavy
with the QPF & as well as being too far northwest; there are a few
things we need to consider. There are some indications of a band of
pretty intense 700 mb frontogenesis and good snow growth on the
northwest side of the storm. We also should mention there are
decent mid level lapse rates and a -EPV signature. This may result
in 1-2 inch per hour snowfall rates for a time especially late
Sunday morning and Sunday afternoon. In addition, a period of good
SLR/s would occur in this band especially if it is able to reach
northwest of I-95, where surface temperatures will be colder.