240
FXUS61 KCTP 301914
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
314 PM EDT Wed Sep 30 2026

.WHAT HAS CHANGED...
* Increased rain chances across the northern tier tonight into
  Thursday morning.
* Elevated frost risk beginning Monday night continuing through
  Tuesday night with cooler temperatures and light wind.

&&

.KEY MESSAGES...
1) Showers across the northern tier overnight into Thursday,
trending closer to climatological averages to begin October.

2) Frost/freeze concerns across portions of central
Pennsylvania early next week, beginning on Monday night and
continuing through Tuesday night.

&&

.DISCUSSION...
KEY MESSAGE 1: Showers across the northern tier overnight into
Thursday, trending closer to climatological averages to begin
October.

An upper-level trough will bring some light rain across the
northern tier overnight into Thursday morning. At this time,
best odds based on a combination of NBM/HREF guidance hones in
on areas north of Interstate 80 as the most likely to experience
rainfall overnight. Some members of hi-res model guidance do
indicate that rainfall could reach as far south as a JST/RVL/ZER
line; however, forecast continues to outline areas north of
I-80 as the most plausible to receive measurable rainfall. In
terms of rainfall amounts, generally light rainfall is expected
with maximum rainfall amounts overnight topping out near 0.10".

More widespread rainfall is projected by all model guidance
along a cold frontal passage. Timing remains fairly consistent
between model guidance, with rainfall beginning closer to
sunrise on Friday. Based on more recent model guidance, areas
west of US-219 could experience first raindrops just ahead of
sunrise, thus have sped up mentions of rainfall in the most
current forecast package. Guidance remains fairly consistent on
the cold front diving southeast throughout the day on Friday
with rain chances beginning to exit the forecast area Friday
evening. Instability associated with this frontal passage appear
to be minimal; therefore, no thunderstorm mentions in the
forecast package.

Outside of a wave tracking south of the region on Sunday,
tranquil weather conditions are expected for the region this
weekend. With regards to the wave, best chances for
precipitation will be south of the Pennsylvania-Maryland border
but cannot completely rule out a shower south of the Turnpike on
Sunday, especially late Sunday morning into the early evening
hours. Any additional rainfall will be light, before dry
conditions prevail Sunday night and continue through the end of
the forecast period.

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

KEY MESSAGE 2: Frost/freeze concerns across portions of central
Pennsylvania early next week, beginning on Monday night and
continuing through Tuesday night.

Early next week, Canadian high pressure begins to build into
the region, bringing much cooler air and dry weather to the
region. LREF ensemble guidance outlines 850mb temperatures
trending close to 0F across portions of northern Pennsylvania as
early as Monday night, outlining the cooler temperatures that
are expected for the beginning of the week. This high pressure
will lead to very light wind and mainly clear skies across much
of central Pennsylvania, so the biggest question mark with
respect to frost will be how low temperatures get and if this is
sufficient for frost formation. At this time, current forecast
outlines MinTs closer to freezing north/west of the Allegheny
Front confidence is higher in some frost/freeze concerns.
Further south/east, there is a larger spread in guidance with
respect to temperatures, so confidence remains lower; however,
generally would urge those with agricultural interests to
continue to monitor the forecast closely this weekend into the
beginning of next week.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
Lower ceilings are sticking around longer than expected over the
northern and western terminals with more moisture than expected
present in the lower levels. BFD and JST are hanging onto MVFR
cigs, but they should scatter to VFR within the next few hours.
Dry surface conditions are expected to persist through the
remainder of today before moderate warm advection associated
with a shortwave tracking to our north into Thursday morning
will support light rain developing over the northern half of the
region after 00Z Thursday. As of now, it appears that rain
could make it as far south as UNV, but confidence is highest in
BFD and IPT seeing measurable precipitation. The rain should be
pretty light and cloud bases don`t look to get below 5000 feet,
so expect mainly VFR conditions to continue. There remains a
low probability (30-40%) of lower CIGS again Thursday morning in
BFD and IPT as clouds persist, but VFR ceilings will be
prevailing through tomorrow almost everywhere.

Outlook...

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

Thu Night - Fri...Cold FROPA with showers along the front. LLWS
possible, especially northern and western TAF sites.

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.

Mon... Dry conditions with VFR prevailing.

&&

.CLIMATE...
Soggy September Soaker...
September 2026 (MDT) 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...Beaty
KEY MESSAGES...Beaty
DISCUSSION...Beaty
AVIATION...Bauco/Bowen
CLIMATE...Steinbugl