Area Forecast Discussion
Issued by NWS State College, PA

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467
FXUS61 KCTP 100220
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
920 PM EST Sat Dec 9 2017

.SYNOPSIS...
Low pressure will move off the mid Atlantic coast tonight.
A deep upper level trough will remain over the eastern conus
into Thursday, before a westerly flow of milder air works
into the area by next weekend.

Low pressure moving just north of the area late Sunday will
bring some snow to the north and west Sunday into Sunday
night. Another low moving just north of the area late Monday
night will bring some snow to the area late Monday into Tuesday,
mainly across the north and west.

&&

.NEAR TERM /UNTIL 7 AM SUNDAY MORNING/...
In a little break right now. Finally rid of the snow in the SE.
Clear slot over the central counties moving west. The higher
clouds in the west continue to move east and thicken somewhat.

A strong short wave will move overhead shortly, leading to NVA.
As the trough axis moves eastward, snow showers will pop in the
cold air to the west of the trough. Accumulations will be very
light, less than an inch almost everywhere by sunrise. The
winds are also favorable for a brief period of lake effect late
tonight and the first part of Sunday. So, Warren county could
get more than an inch by sunrise. But, bands look to be rather
transitory. Clearing may be tough to find, but the SE may
become clear shortly and hold on all night. Winds will pick up
in the SW and get gusts over 20kts.

&&

.SHORT TERM /7 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
Aside from aforementioned lake effect snow into Sunday
afternoon, downsloping subsidence should result in partly
sunny, dry weather east of the mountains Sunday. Mixing down
model 850mb temps of -10C to -12C translate to below normal max
temps Sunday, ranging from the upper 20s over the Alleghenies,
to the mid 30s in the Susq Valley. The gusty west wind will add
an additional bite to the air.

Ensemble qpf supports accums generally less than an inch across
the Allegheny Plateau by late Sunday. However, the favored
snowbelt of northwest Warren could be around 3 inches.

&&

.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
A weak low moving north of the area will bring a northwest
flow of air to the area late Sunday into early Monday. This
will result in some snow showers.

A stronger low moving across upstate New York on Tuesday will
bring some snow to the area late Monday night into Tue. THis
will be followed by a cold northwest flow across the Great
Lakes. This will result into some snow showers off the lakes.

The west coast ridge weakens some toward next weekend, which
will result in a westerly flow of milder air working into the
area.

Minor changes to the package.

Went with dry conditions next weekend.

&&

.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
VFR conditions north...transitioning to MVFR to IFR southeast
as snow impacts especially York and Lancaster Counties. Best
window for reductions in the Lower Susq will be through 00z,
while remainder of CWA remains primarily VFR.

Then focus will shift to a trough moving in from the NW tonight,
bringing restrictions and widespread snow showers to the
northern/western mountains along with brisk NW flow and the
potential for scattered heavier squalls that will linger into
the first half of Sunday. Scattered snow showers will bring
intermittent MVFR incursions into the central mountains, while
downslope flow will keep the SE VFR.

Outlook...

Sun...AM snow showers/reductions likely Allegheny Plateau,
becoming confined to the NW mtns in the afternoon. Scattered
squalls also poss.

Mon...Cig reductions likely western portions. PM light snow
developing, mainly northwest Pa.

Mon night and Tuesday...Periods of light snow. Widespread MVFR
likely, with periods of IFR and brief LIFR cigs and vsbys.

Wed...Reductions poss west in sct snow showers. Otherwise VFR.

Thu...Still a chance of a few snow showers.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 1 AM to 3 PM EST Sunday for
PAZ004.

&&

$$
SYNOPSIS...Dangelo
NEAR TERM...Dangelo
SHORT TERM...DeVoir/Fitzgerald
LONG TERM...Martin
AVIATION...DeVoir/Martin/RXR



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