Area Forecast Discussion Issued by NWS State College, PA
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000
FXUS61 KCTP 180901
AFDCTP
Area Forecast Discussion
National Weather Service State College PA
501 AM EDT Mon Mar 18 2024
.SYNOPSIS...
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An upper level trough will swing across Pennsylvania today,
followed by a reinforcing shortwave and associated cold front on
Wednesday. High pressure is likely to build over the area
Thursday. A dying cold front is likely to approach from the
Great Lakes late next week, as a southern stream shortwave
passes well south of the state.-- End Changed Discussion --
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
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SCT SHSN rolling across the area, but the only ones bringing
the visibility low enough and places with temperatures low
enough to generate any accumulations are just N of I-80 and
dropping into Lock Haven and Williamsport at 4 AM EDT. There is
very little organization to the SHSN and they are moving
quickly. Expect only a dusting this morning. There aren`t many
breaks in the cloud shield back over nrn OH and lower MI.
Daytime may mix things up a little better, and lead to some
breaks. The long wave trough swinging overhead today will
continue to generate a broad area of lift and potentially lead
to steep lapse rates/instability. The latest snow squall
parameter values from the HRRR and NAM maximize in the evening
as a good sfc trough moves across the lower lakes and into the
NW mtns/Alleghenies. Frontogenesis is weak through the period,
and at that time, we would also be losing the help of the
heating to lower the stability. Plenty of snow showers, and it
will be gusty, too, but it`s not the best set-up. Flash freeze
possibilities look generally poor. The NW is the only worry
spot for squalls. General accumulations will be less than an
inch NW and less than an inch for the central mtns. SCT SHSN do
last into the night over the Laurels, but accums there will be
very minor. Even if some flurries fly in the SE, the temps
should be mild enough (m40s) to melt anything that tries to
stick.-- End Changed Discussion --
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.SHORT TERM /10 PM THIS EVENING THROUGH TUESDAY NIGHT/...
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After the troughs overhead and at the sfc pass, the subsidence
should quell the SHSN/SQ for at least the next 18 hrs into late
Tuesday. The ridging should also push lake effect snows to our
N. A northern stream wave/Clipper moves across ONT into NY late
on Tuesday and does not bring the coldest of the air across PA
until Wed. The warm advection does nudge into PA. The
associated cold front will not arrive until the overnight. That
will likely touch off SCT SHSN, but squalls should not be very
likely without much instability. Mins tonight will be below
freezing for all. Temps on Tuesday will be very similar to
today/Monday. The warm advection and more clouds Tuesday night
will keep the mins up just a little vs tonight - in the u20s to
m30s.-- End Changed Discussion --
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.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
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The passage of the trailing cold front Wednesday should be
accompanied by scattered snow showers, a few of which could
survive into the Susq Valley due to strong forcing ahead of the
upper level shortwave. Steep lower tropospheric lapse rates
indicate the potential of some heavier snow squalls, mainly
across the N Mtns. Fair, but still cool, weather appears likely
Thursday, as the trough lifts out and surface ridging builds in
from the Grt Lks.
Medium range guidance suggests a few rain showers are possible
Friday, mainly over the N Mtns, associated with the approach of
a dying cold front. The bulk of guidance tracks a more
significant southern stream shortwave and associated area of
low pressure well south of PA next weekend. Therefore, fair and
seasonal conditions currently appear likely next Sat/Sun.-- End Changed Discussion --
&&
.AVIATION /08Z MONDAY THROUGH FRIDAY/...
Mainly high clouds are present in the airspace this evening with
a few spots that contain broken MVFR cigs, mainly in the western
mountains. Isolated lake effect snow showers are possible in the
NW, everywhere else should expect dry, cold, and some breezy
conditions.
Borderline VFR/MVFR cigs could spill into the central mtns
(AOO, UNV, IPT) during the late evening hours as cooling aloft
occurs with the approach of a few upper level disturbances. The
Lower Susq Valley (MDT, LNS) should remain VFR right through
tonight and Monday.
West-northwesterly wind will frequently gust between 20 and 25
MPH this evening, before subsiding by 5-10 mph overnight then
picking back up to similar speeds and gusts around mid morning
as mixing occurs in the lowest levels of the atmosphere.
Outlook...
Monday-Friday...Periodic snow showers and reductions, primarily
across the higher terrain of northern and western PA. This will
be enhanced by reinforcing shots of unseasonably cold air and
gusty W/NW winds. West to northwest wind gusts could peak in the
35 to 40 mph range on Wednesday.
&&
.CLIMATE...
Astronomical Spring (vernal equinox) begins on Tuesday March 19
at 11:06 PM EDT.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Fitzgerald/Dangelo
NEAR TERM...Fitzgerald/Dangelo
SHORT TERM...Fitzgerald/Dangelo
LONG TERM...Fitzgerald
AVIATION...Bowen
CLIMATE...Steinbugl