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176
FXUS61 KCTP 182249
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
649 PM EDT Wed Sep 18 2024

.SYNOPSIS...
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*Mostly cloudy tonight with a lingering shower possible over
 Southern PA
*Little to no rainfall expected Friday into early next week
 perpetuating one of the driest September`s so far on record
*Daytime temperatures peak +5-10 degrees above average Friday
 and Saturday before trending seasonably cooler next week
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&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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Regional radar loop at 2245Z shows just a few isolated
showers/sprinkles over Central/Southern PA, while patchy drizzle
over the Laurel Highlands can be inferred by the low cigs and
upsloping easterly flow in that area. A weak surface low off of
the Delmarva Peninsula and the associated plume of Atlantic
moisture is progged to exit the area overnight, while backing
low level flow to the northeast advects drier air into the
region. Therefore, expect any lingering light showers/drizzle to
further diminish in coverage, especially over the central
counties.

Low dewpoint depressions going into the evening, combined with
light winds and some partial clearing, should result in patchy
late night valley fog. See no reason to deviate from NBM min
temps, which range from the low 50s over the mountains north of
KIPT, to the low 60s across the Lower Susq Valley.
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&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/...
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Patchy valley fog, and possibly some lingering stratus over the
southwest part of the forecast area, should give way to
mostly sunny skies by Thursday afternoon, as surface ridging
builds in and the associated northerly flow advects drier air
into Central PA. The brightest skies should be over the western
half of the state, while southerly flow/waa aloft linked to a
cut-off low over VA could result in a lingering veil of cirrus
over the eastern half of PA. The return of sunshine should
result in a marked jump in max temps compared to today. GEFS 2m
temp anomalies support highs in the upper 70s to low 80s for
most of the area.

Surface ridging building over the region should result in fair
and warm weather Friday into Saturday, with patchy morning
valley fog a good bet. Latest global guidance tracks a weak
shortwave just north of PA Saturday. However, this feature
should have little moisture to work with and the best forcing
is progged to pass north of the state. Therefore, leaving
mention of showers out for now. Max temps may be slightly lower
Saturday, due to low level flow veering to the east off of the
Atlantic.
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&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Much of the model guidance remains dry for Sunday, but the GFS
shows an outlier solution where a few showers ahead of a warm
front make it into west central PA. While model variability
remains elevated into next week, the ensemble means generally
favor weak upper troughing centered around the Great Lakes which
will support a marginal increase in rainfall/shower potential
along/ahead of an approaching front by next Monday or Tuesday.
Forecast max temps 75-80F peak +5-10F above mid/late September
climo to start the weekend and trend modestly cooler to 65-75F
(near the historical average) into early next week.

&&

.AVIATION /22Z WEDNESDAY THROUGH MONDAY/...
Pockets of light rain will gradually diminish over the southern
half of the airspace through the evening. The highest confidence
and max probability of MVFR/IFR cigs will be around KJST/KAOO
prior to 19/00Z with VFR expected elsewhere across the airspace.
Conditional risk of fog/vis restrictions overnight especially
at KBFD/KIPT where skies may partially clear out. A much drier
flow pattern will allow for trending/prevailing VFR conditions
through the end of the week.

Outlook...

Thu...Trending VFR.

Fri-Mon...Valley fog in the morning; otherwise VFR/no sig wx.

&&

.CLIMATE...
The first day of Autumn 2024 (Fall Equinox) begins at 8:44 am
EDT on September 22nd.

&&

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

&&

$$

SYNOPSIS...Steinbugl
NEAR TERM...Fitzgerald
SHORT TERM...Fitzgerald/Steinbugl
LONG TERM...Steinbugl/Colbert
AVIATION...NPB
CLIMATE...NPB