.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
In the extended, all attention remains on model details
associated with storms system tracking towards the mid Atlantic
coast Sunday night and Monday. Model consensus showed a slight
northward jog in QPF/snowfall overnight, only to return farther
south with a flatter wave solution with 12z runs this (Fri)
morning. Negative NAO/Positive PNA pattern means we`ll have to
keep watching closely for the evolution, although upstream
blocking high is absent which should act to favor the flatter
wave and southern solution, keeping heaviest snowfall along and
south of the Mason Dixon line. Still, this track will bring
plowable snowfall to at least the southern third to maybe half
of central PA beginning late Sunday night and continuing Monday,
with many more details still yet to be determined heading into
the weekend. Very preliminary ballpark ideas are that a coating
to 2" could be in play across the central mountains, with 3-5
inches or more possible along the southern tier.
In snowier solutions that only comprise 25% of members, the
wave packet is more amplified allowing moisture to advect
farther northward and jet forcing to be stronger. This could
force the heaviest snow axis to land within our CWA, but again
a flatter wave solution is favored at this time due to
aforementioned factors.
PoPs remain high and all snow Sunday night into early Monday,
with snow likely winding down through the latter half of Monday.
The storm is not fully within the 72-hour range of
deterministic QPF and snow forecasts.