589
FXUS61 KCTP 300135
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
935 PM EDT Tue Sep 29 2026

.WHAT HAS CHANGED...
* Bumped up sky cover many places, especially next 6 hrs, and
  adjusted temps/fog coverage accordingly.

&&

.KEY MESSAGES...
1) Cloud cover a real challenge for the overnight, and will have
a big effect on temps and fog formation.

2) Noticeable warmup and several days of dry conditions to end
September and start October

3) Cooling trend this weekend into early next week with an
increasing chance of rain Saturday and Sunday.

&&

.DISCUSSION...
KEY MESSAGE 1: Cloud cover a real challenge for the overnight,
and will have a big effect on temps and fog formation.

Clouds hanging in for now, but are showing signs of thinning
some per latest nighttime microphysics RGB composite imagery
loop. Expect more thin spots and eventual breaks to occur, but
our CWA really hasn`t moved much in terms of the footprint of
the 100% sky cover area. Still, some clearing is expected, but
slowly, and some places may not have any clearing before
daylight.

Previous...

Satellite obs and METARs show the few breaks of this aftn have
closed up. However, the clearing over Warren County is real and
should continue advancing eastward over the next few hours.
However, there is a big discrepancy between guidance at T=0 and
what`s on the Sat images. Therefore, confidence is very low on
the speed and extent of clearing tonight. Have slowed down the
clearing, mainly where the clouds are thickest and the RH
guidance keeps the numbers highest later tonight (NE). Very
tough forecast. MAV/MET MOS still paints a very cloudy and foggy
picture at JST and fogginess at BFD later tonight. The
northwest wind will get lighter soon, but the upslope into JST
with lingering moisture is usually a strong sign of poor
visby/low cigs there. Have kept a mention of patchy fog almost
everywhere overnight. But, the extent and thickness of the fog
is highly debatable. Doesn`t hurt to mention it, but this part
of the forecast is usually more impactful to aviation than the
general wx grids/forecasts.

------------------------------------------------------------

KEY MESSAGE 2: Noticeable warmup and several days of dry
conditions to end September and start October

A warmup will last through the mid to late week period with
fcst max temps in the 75-85F range or +10-15 degrees above the
historical normal for the end of September/beginning of October.

For context, the average last date of max temp >=80F is 9/27 at
State College, 9/29 at Altoona, 10/2 at Williamsport and 10/5
at Harrisburg.

A small chance for --RA/SHRA is here for later Wed night and
Thurs AM as a weak warm front aloft (mainly an increase in
moisture) passes overhead. The moisture plume will probably be
thick enough to drop the clouds low enough for a little light
rain to hit the ground over the nrn half of the CWA. The highest
chances will be in the far NW. But, some sprinkles could get
down just south of I-80 around sunrise Thurs.

Showers are again possible on Friday-Friday night associated
with cold front sinking southeastward from the eastern Great
Lakes.

-------------------------------------------------------------

KEY MESSAGE 3: Cooling trend this weekend into early next week
with an increasing chance of rain Saturday and Sunday.

24hr maxT change on Saturday behind the cold front is fcst to
be 10-15 degrees lower vs. Friday with highs in the low 60s/70s.
Trailing frontal wave could bring more widespread soaking rain
on Sunday based on WPC/NBM QPF - although EC/CMC and (to lesser
extent) lean farther to the south/east with the frontal precip.
Confidence is higher that temps continue to cool off and drop
near or below the historical average into early next week. Frost
potential is on the table for next Monday and Tuesday night.

&&

.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
A deck of VFR stratocumulus remains across much of central PA
this evening as low-level moisture wraps around the departing
weekend Nor`easter. River/valley fog is moderately likely
(60-80% chance) to develop overnight where this cloud deck
clears out, which looks to primarily be across our westernmost
terminals (KBFD/KJST/KAOO). Confidence in overnight fog
decreases with eastward extent (towards KMDT/KLNS) where enough
clouds may hold to prevent fog development, though calm winds +
surface dewpoints around 60 F (15.5 C) will conditionally
support localized mist/fog nonetheless.

Overnight fog will have largely mixed out by around 14Z
Wednesday, with VFR favored throughout the day on Wednesday as
high clouds stream overhead alongside fair-weather diurnal
cumulus. With that said, a small chance (10-20%) exists for
intermittent MVFR ceilings in the late morning/early afternoon
(mainly 15-18Z) as the boundary layer deepens.

Outlook...

Thu...-SHRA possible, mainly over northern PA, with potential
for localized AM mist/fog.

Fri...Cold FROPA with showers along the front.

Sat-Sun...VFR favored behind the FROPA, with lower confidence
across southern PA where lingering moisture may bring intervals
of low ceilings (primarily MVFR). AM fog possible.

&&

.CLIMATE...
Soggy September Soaker...
September 2026 (MTD) precipitation rankings
IPT: 11th wettest (6.84")
MDT: 26th wettest (4.72")
AOO:  9th wettest (5.58")
BFD: 10th wettest (4.85")
JST:  3rd wettest (7.31") *since 2000
STC:  6th wettest (7.90")

&&

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

&&

$$

WHAT HAS CHANGED...Lambert/Dangelo/Steinbugl
KEY MESSAGES...Lambert/Dangelo/Steinbugl
DISCUSSION...Lambert/Dangelo/Steinbugl
AVIATION...Teare
CLIMATE...Steinbugl