022
FXUS61 KCTP 231329
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
929 AM EDT Sun Aug 23 2026

.WHAT HAS CHANGED...
Adjusted POPS up for Central and Southern PA today by about 20
percent from NBM guidance.

&&

.KEY MESSAGES...
1) Unseasonably deep upper low over the Upper Great Lakes today
will move Southeast to Lake Ontario by Monday morning bringing
another few rounds of showers and thunderstorms, mainly across
Northern PA this afternoon and evening.

&&

.DISCUSSION...
KEY MESSAGE 1: Unseasonably deep upper low over the Upper Great
Lakes today will move Southeast to Lake Ontario by Monday
morning bringing another few rounds of showers and
thunderstorms, mainly across Northern PA this afternoon and
evening.

A subtle shortwave trough rotating around the southeast side of
the upper low will spark some afternoon/evening showers and TSRA
today, followed by only a brief downtrend in convection before a
well-defined trough moves SE with its axis near the PA/OH border
by shortly after midnight tonight.

HREF and SREF MUCAPEs will top out between 750-1000 j/kg with
wet bulb zero levels descending about 3-4 KFT to only around 6
KFT AGL across the Northern Mtns this afternoon and tonight.
It`s almost a slam dunk to see some periods of significant small
hail from the stronger low-topped TSRA between 18Z Sun and 00Z
Monday across the NW and maybe the Central/Ncent Mtns. SPC has a
marginal risk of SVR TSRA for today across all of the CWA except
for the southern tier layer of counties. Coincidentally, NBM
POPS had to be raised by at least 20 percent (to agree with the
SPC outlook) across the Central and Scent Mtns along with much
of the Middle and Lower Susq Valley where a relative min of zero
to 10 POPs was noted.

Luckily, this second and more potent upper trough will be
pivoting over the Commonwealth overnight tonight with MUCAPE of
only a few hundred J/KG, supporting mainly showers and perhaps a
low-topped TSRA or two moving inland from the warm waters of
Lake Erie.

Maxes only in the 60s and a brisk W wind across the northern and
western mtns will make it feel much more like Sept/Oct than
mid- Aug. Valley locations will see more sun preceding any
convection with high temps reaching the mid 70s to near 80F in
the Lower Susq Valley.

Similar conditions are expected for Monday with the center of
the upper low still hanging around our longitude and only moving
slowly poleward. The SHRA/TSRA will likely be confined to only
the nrn tier of counties in PA on Monday.

&&

.AVIATION /13Z SUNDAY THROUGH THURSDAY/...
Mid morning update.

Adjusted the current TAFS for current obs and also small
clusters of showers and isolated storms.

Earlier discussion below.

MVFR will predominate most airfields through the mid morning
hours with pockets of lower IFR ceilings due to upslope flow at
KBFD and KJST. We`ll see a transition with varying VFR and MVFR
in SHRA/Isolated low-topped TSRA focused in the 19-23Z window.
Westerly wind gusts of 25+ Kts and small hail (GS) are possible
across the northern Mtns of PA including KBFD.

Cooling temperatures aloft and a 20+kt 850mb westerly jet
should allow for moderately gusty winds for the late morning and
afternoon hours.

Outlook...

Mon-Wed...Patchy morning fog, otherwise mainly VFR conditions
return early next week with lower statewide precipitation
chances.

Thu...Chance of showers and storms again.

&&

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

&&

$$

WHAT HAS CHANGED...Lambert/Dangelo
KEY MESSAGES...Lambert/Dangelo
DISCUSSION...Lambert/Dangelo
AVIATION...Lambert/Martin/Lambrech