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Area Forecast Discussion (AFD)

Issued by State College, PA (CTP)

                            
000
FXUS61 KCTP 210615
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
215 AM EDT Sat Sep 21 2019

.SYNOPSIS...
Anomalous upper level ridging will build east into the region
through the weekend. A cold front will likely push across the 
area Monday, followed by high pressure building in from the 
Great Lakes by the middle of next week.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Upper level shortwave over the eastern Grt Lks will push
southeast tonight, accompanied by nothing more than a bit of
cirrus. Can't completely rule out a shower around dawn over the
Laurel Highlands, where higher pwats will arrive ahead of
shortwave. 

Mostly clear skies and a calm wind should promote patchy late
night valley fog across central and northern Pa. Mins won't be 
as chilly as recent nights given return flow aloft, but should 
range through the 50s in most places, with a few upper 40s
possible in the normally colder northern valleys.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SUNDAY/...
No significant changes to the forecast on Saturday, as the 
strong surface high slips southeast of the region. A return 
southwest flow of warmer, more humid air will develop accompanied
by partly to mostly sunny conditions. Max temperature departures
of +10-15 degrees are expected Sat with peak readings in the 
mid 80s in the SE. 

Diurnal heating of increasingly moist, unstable air mass,
combined with upper level trough, should support a few showers 
over the western counties, primarily during the afternoon. The 
best large scale forcing, as inferred by model 500-300mb qvec 
convergence fields, will be across southern Pa. Therefore, have 
placed the highest POPs of around 30 pct across the Laurel 
Highlands and south central mountains, where the best 
combination of instability and large scale forcing is progged.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Heights and temps aloft will rise again Sat night and Sunday, 
leading to a fair conditions at night and mostly sunny and a
pleasantly warm early Autumn day with temps well into the 70s 
across the northern and western mtns, and at least the mid 80s 
in the SE zones.

The models are coming into agreement on the tracking of a cold 
front that will move through the area Monday. This system will 
likely be accompanied by a round of generally light showers. It
should move through the region quickly with a return to fair 
and slightly warmer than seasonable weather Tue/Wed. High 
pressure should build southeast from the Grt Lks mid next week.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
Localized valley fog restrictions early this morning will give
way to VFR. An increase in low level moisture should result in
scattered cumulus this afternoon with a spotty/isolated shower 
possible across the western 1/2 of the airspace. Valley fog is
likely to redevelop tonight with local restrictions into early 
Sunday morning.

.Outlook...

Sun...AM fog. VFR. 

Mon...Sct showers/isold t-storms as a cold front crosses the 
area.

Tue...MVFR cigs possible north/west.

Wed...VFR/no sig wx.

&&

.CLIMATE...
Autumn officially arrives at 3:50 a.m. EDT, on Monday, Sept. 23.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$
SYNOPSIS...Fitzgerald
NEAR TERM...Fitzgerald
SHORT TERM...DeVoir/Fitzgerald
LONG TERM...Lambert/RXR
AVIATION...Steinbugl
CLIMATE...Steinbugl