071
FXUS61 KCTP 301802
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
202 PM EDT Thu May 30 2024

.SYNOPSIS...
An upper level trough will swing over the region today, then
Canadian High Pressure will build southeast into Pennsylvania
Friday and Saturday. The high will pass off the East Coast by
late this weekend into early next week, then a cold front will
likely traverse the state next Thursday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Bright sunshine over much of the area this morning under
influence of high pressure and much drier air aloft. Some
moisture trapped in the subsidence over the Laurel Highlands is
slowly mixing out at mid morning and should give way to mostly
sunny skies by late morning.

Diurnal heating, combined with cool temps aloft and large scale
forcing ahead of an upstream trough, should support some
cumulus development and perhaps an isolated afternoon shower,
despite the arrival of drier air. The highest POPs of around 15
pct are painted across south-central PA, where models indicate
slightly better low level moisture.

Mixing down 800mb temps of 1-2C supports max temps ranging from
the low 60s over the N Mtns, to the low 70s across the Lower
Susq Valley. Forecast soundings showing dry air above a weak
inversion supports undercutting NBM dewpoints this afternoon by
a few degrees.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/...
Nearly ideal conditions for radiational cooling are setting up
tonight across the western half of PA, as the upper trough lifts
out and Canadian High Pressure builds in, accompanied by clear
skies, dry air and a calm wind. Therefore, we have leaned
toward the cooler MAV temps tonight in place of NBM guidance,
with expected lows ranging from the mid 30s in the colder
valleys of the NW Mtns, where patchy frost is likely, to the
upper 40s over the Lower Susq Valley. A large water/air temp
difference of >25 degrees also favors patchy late night fog in
the deep river/stream valleys of the NW Mtns.

Large scale subsidence and low-pwat air points to abundant
sunshine Friday, as high pressure pushes into the state. Mixing
down 850mb temps of around 8C translates to highs from the upper
60s to mid 70s. Friday night should be another cool one, as the
surface high builds directly over PA, resulting in clear skies,
a calm wind and min temps below NBM guidance. The airmass in
general should be moderating, so expect readings not quite as
cool as tonight.

Upper level ridging is progged over PA by Saturday, as the
surface high slips off of the East Coast, resulting in a mostly
sunny and warmer start to the weekend. GEFS 2m temp anomalies
Sat afternoon are few degrees above climo, translating to highs
of 75-80 over most of Central PA.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
A shortwave trough moving through the region late Saturday
night into Sunday. This feature will bring the next chance of
showers and thunderstorms to central PA.

Longer range guidance shows multiple shortwaves moving through
the region into the middle of next week bringing renewed chances
for showers and storms. PoPs have decreased for Monday, which
now looks like it will be a generally dry day. Chance or greater
PoPs return for Tue-Thu.


&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
VFR conds prevail today with SCT-BKN fair weather cu. Northwest
winds gusting up to 20 kts will weaken after sunset. Dewpoints
will be quite low tonight, thus expecting mainly clear skies
with very little potential for fog overnight into Friday
morning, except for the deepest river valleys.

Outlook...

Fri-Sat...Mainly clear skies with VFR conditions.

Sun-Mon...Showers and thunderstorms possible.

&&

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

&&

$$

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