LWX discussion:
As we head into Sunday morning, clouds will rapidly return as
the low over the south starts to turn the corner and head
northward toward us. This will limit insolation, keeping it cold
to start. By late morning, snow will then begin overspreading
the region as the low strengthens and heads northward toward us.
Unlike the last two widespread winter storms, which were
dominated by frotogenesis (January 3rd) or upper-dynamics
(January 7th), this one will be dominated by intense warm
advection. It will be accompanied by a strong easterly fetch as
the high shifts eastward off the coast to our north. Thus, the
effect of the cold air mass which will be in place to start will
be less enduring as the intense warm flow eats away at the cold.
That said, this will also enhance precipitation, resulting in
most areas seeing at least a brief period of moderate to heavy
snow before changing over to sleet and freezing rain and, for
some, plain rain.
Guidance continues to shift around a bit, but latest trends have
mostly been westward. This has resulted in a shiftward west of
the heaviest snow and best icing potential, with more potential
for a change to rain over areas near and east of I-95. It also
intensifies the wind threat a bit near the shore, with close to
advisory winds now expected. Watches were converted to warnings
and advisories based on our latest expectations on accumulations
and timing. That all having been said, its still nearly 24 hours
before the storm arrives for most, so some additional shifting
around is possible.
Precipitation will wind down from south to north late Sunday
night as the storm pulls away. The exception will be along the
Allegheny Front, where snow will continue much of the day
Monday before tapering off at night. The storm`s departure will
also herald a moderation of the air mass, as a more Pacific-
origin high overspreads the area. This will allow temps to rise
into the 40s Monday, with *only* 20s for lows at night. However,
this will be accompanied by a very strong west wind, potentially
wind advisory levels, with gusts to 50 mph possible across much
of the area. These winds should dwindle by sunset.
