If one excludes the GEM/RGEM, storm-total liquid-equivalent
precipitation remains rather remarkably consistent across the
deterministic and global ensemble guidance at around 0.3-0.4". Other
than across Cape Cod and the South Coast where rain may mix in, this
would ordinarily only support an Advisory-type snowfall around
3-5" at SLRs of 10 to 13:1. However, both 00z NAM and GFS
indicate a zone of 850 mb speed convergence and associated W-E
band of 850 mb frontogenetic forcing with some -EPV lifting N/NE
from central CT/central RI this afternoon. This should support
the development of localized bands of moderate to potentially
heavy-intensity snows for a few-hr period near and north of the
Mass Pike, coinciding with the PM commute. These bands are
supported by 00z HREF 1-hrly snowfall progs, which suggest inch
per hour snow rates could be achievable in the winter storm
warning area, with low visbys to boot. In addition, WPC runs
experimental Snowband Probability graphics which depict the
potential for mesoscale snowbands, and a number of members
indicate the potential for such bands during the 19-23z
timeframe. These are often challenging to pinpoint and it`s not
out of the question areas in northern CT and northwest RI could
get in on these bands as well; Omega in the snow growth region
is also a lot less, which should keep us from seeing the intense
snow rates we saw from e.g. Sunday. But, snow amounts were
increased around 1-2" inches in the winter storm warning area to
around 5-7" (isolated/local higher in persistent steady-state
bands), around 3-6" across northern CT, Providence County in RI
and up towards Norfolk and the Greater Boston area. Amounts
taper further south and east to the 2-4" range for southeast MA
into central RI, and generally 1-3" near the South Coast/Cape
where rain may mix in at times.