Nice overnight trends for CNE and far western SNE:
WPC
Recent 00Z guidance has shown a little stronger confluence over
Quebec than previous runs that is limiting the northerly extent of
the precipitation field. Guidance does maintain a potent upper
trough over the Mid-South on approach, but the aforementioned
confluent flow is forcing the trough to remain more
positively-tilted in the 500mb layers by 06-12Z Monday. This is
leading to the best frontogenetical forcing and strongest vertical
ascent beneath the right-entrance region of the 250mb jet streak
to become positioned more offshore rather than over central New
England, rather than a more robust, intense FGEN setup over
northern New England. Think the latest PWSSI is showing a
reasonable swath of >40% probabilities of Moderate impacts from
the Catskills and southern Adirondacks to the Green and White
Mountains of VT and NH respectively, and across central ME. These
areas can still witness some banding on the northern flank of the
850mb low as it tracks south of Long Island and off the
Massachusetts Capes by early Monday morning.
GYX
The keys to this forecast, especially the rain/snow line, will be pinning down the track of the low- and mid-level circulations amid only a marginally-supportive air mass for snow. Ensemble consensus brings the surface low SW to NE across Cape Cod or just beyond it before deepening over the Gulf of Maine; tracks closer to the coast introduce warmer air through the low levels... although it would be an outlier solution to come close enough to the coast to jeopardize snow accumulation over the interior, especially when considering the 21.00Z solutions flowing in this morning trending southward. Thus fairly strong confidence exists for interior zones to remain all-snow, except in the warm Merrimack Valley and toward the Mass border as a whole. Even slightly more southern tracks bring snow to the Maine coast with more favorable northerly drainage flow reinforcing sub-freezing conditions in the low-levels. Latest ensemble solutions also favor a near- or just-south-of- the coast track for the mid-level circulation... leaving the coast-ward half of the forecast area in a favorable region for classic deformation/FGEN forcing... most pronounced over central/southern Maine, where the amplifying low over the Gulf of Maine will increase forcing overhead. Regardless of the circulation`s track... UVVs are likely to be concentrated in the mid-levels with a fair amount of DGZ overlap before snow falls through a deep isothermal layer...likely to be right around freezing closer to the parent circulation. Latest ENS/GEFS solutions show about a 50-70% chance of keeping this layer below freezing at the coast; while I don`t think this is enough to include the Midcoast in the watch just yet, this would be the area to look at for trends favoring a more southern low track, which may allow strongest forcing to tap into cooler air and produce strong snowfall rates on Monday.
Would be nice to get a daytime storm
