554
FXUS61 KCTP 161829
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
229 PM EDT Wed Sep 16 2026

.WHAT HAS CHANGED...
* Minor adjustments to precip probs (% chance) and dewpoints
  through Thursday

&&

.KEY MESSAGES...
1) Warmer and more humid conditions promote increasing odds for
rain through Thursday

&&

.DISCUSSION...
KEY MESSAGE 1: Warmer and more humid conditions promote
increasing odds for rain through Thursday

Sfc dewpoints are up +15 to +25 degrees since early Tuesday
morning, marking the return to warmer and more humid sensible
weather conditions across CPA. Ongoing heating/destabilization
of very muggy, high dewpoint air (Td 65-70F) across west-
central PA will lead to moderate CAPE values by mid afternoon.
Widely scattered thunderstorm development is expected, in a
regime of relatively weak westerly flow aloft and poor mid
level lapse rates. PWAT values approaching 2 inches could favor
a few locally heavy downpours. Continued low level WAA and
slowly declining MUCAPE suggest scattered showers and storms
could persist overnight into early Thursday morning with HREF
PMM signal focusing max POPs over the western Alleghenies.

A subtropical high aloft will persist over the southern Plains
and lower MS Valley through tomorrow. Around the periphery of
the high and in response to a shortwave trough crossing ON/QC, a
surface cold front will move slowly south/southeastward from the
lower Great Lakes across Pennsylvania and adjacent states. This
baroclinic/frontal zone will provide a trigger for showers and a
few thunderstorm clusters through Thursday evening. The threat
for severe storms is low enough that SPC has not introduced
probabilities with the D2 update. WPC will maintain a level 1
excessive rain risk over the west-cetentral Alleghenies given
high pwats and above normal rainfall over the past 7-10 days.
While it`s very likely that most of central PA picks up some
rainfall by Thursday night, we do not anticipate a washout.

Another taste of Fall is on the way for the end of the week with
noticeably cooler and much drier/less humid air poised to return
behind the front (Td crashing into the 40s/50s). Expect a crisp
and cool overnight Friday/Saturday morning with some upper 30s
possible across the northern tier. Dry/fair wx conditions are
forecast to start the weekend and last through the day on
Saturday followed by periods of rain Saturday night through
early next week.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
VFR expected across most of CPA into tonight. KBFD is the
exception with model guidance supporting MVFR to IFR conditions
tonight into early Thursday. Can`t rule out a stray shower or
t-storm around KJST/KAOO/KUNV vicinity later this afternoon into
tonight, however probs are currently low enough not to mention
with the 16/18Z TAF package. Expect variable flight cats heading
into Thursday with some patchy fog possible early in the morning
followed by scattered showers and a few t-storms in advance of
cold front moving south/southeast from the Lower Great Lakes.
Wind shift to 300-360 degrees by Thursday night will spell a
return to VFR to end the week.

Outlook...

Fri-Sat...valley fog in the morning; otherwise VFR.

Sat night-Monday...periods of rain and sub-VFR likely.

&&

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

&&

$$

WHAT HAS CHANGED...Steinbugl
KEY MESSAGES...Steinbugl
DISCUSSION...Steinbugl
AVIATION...Steinbugl