058
FXUS61 KCTP 070158
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
958 PM EDT Mon Oct 6 2025

.SYNOPSIS...
* Showery weather will cross the Commonwealth later tonight
  through early Wed morning, associated with an incoming cold
  front
* Breezy and Chilly for Wednesday morning as the rain ends
* Drier and much cooler weather for Wednesday afternoon through
  Saturday

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Patchy mid and high clouds were drifting across the region this
evening. Clouds will increase/thicken up from the SW late
tonight/early Tuesday as the nose of a southern southwesterly LLJ
segment helps to advect a plume of tropical moisture (with
Central GOAM origin) NE up the Ohio River Valley.

Temps ranging from the mid 60s across the NW Mtns to the low
70s (SE) will fall another 8-10 deg F then flatten out to a
large extent aft 07Z.

Latest hi res guidance shows some spotty light showers drifting
across NW half of the CWA after 07Z with more numerous showers
or even steady light rain entering the NW and WCentral Mtns of
the state around 11-12Z Tuesday.

Previous Disc...

Tongue of best moisture dosen`t arrive in the NW until morning.
But, there is a little lift aloft in the late night and early
morning hours in the W. So, many people should get wet over the
wrn mtns around sunrise. Amounts will be very minor. PoPs will
be OK in the 30s around JST-UNV line before sunrise, and 60+ for
the NW mtns. Stability is rather high, so we will keep TSRA out
of the forecast for the overnight.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
Much of the day SE of AOO-UNV-IPT will be fair and very warm
(again). Clouds will get thicker in the aftn. Up in the NW
mtns, early rain will take a short break before additional
forcing arrives. The SHRA don`t look especially heavy, and Storm
total QPF there is <1.00". Continued moisture influx in advance
of the cold front will bring PWAT up to 1.5-1.75". Soundings
are unidirectional in the NW half of the CWA, and CAPE close to
nil. However, some hints of instability exist in the aftn and
early evening. So, a slgt mention of TSRA is OK there. Farther
SE, the NAM is rather optimistic with the QPF/TSRA than the GFS.
GEFS guidance has a very low chc of 1" QPF for much of the
area. If there will be any decent instability over the CWA it
would be in the SE where some heating (dependent on cloud
cover/thickness) could bring -2 LIs depending on your model of
choice. In general, the front should be into the central mtns by
midnight, and pushing past LNS around 12Z. Tried to put some
timing in the gridded PoPs. The cloud cover in the NW half of
the area has a strong possibility to keep temps below NBM
guidance. Have nudged the maxes down there by 1-3F. Kept TSRA
chcs where the NBM has them as instability looks limited. Wind
gets gusty after FROPA over the Allegheny Plateau. Good dry
advection will bring the dewpoints down into the L40s at BFD by
sunrise.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
For the latter part of the work week (Wednesday through Friday),
there is reasonably high confidence that a surface cold frontal
passage early Wednesday will be progressive in nature, pushed on
by a kicker northern stream short-wave trough in the upper
levels of the atmosphere. This should limit clouds and any
lingering showers to early in the day Wednesday, with
improving/clearing conditions by afternoon.

From Wednesday afternoon through Friday, conditions look rain-
free, given the likely advance of a very dry air mass across the
eastern U.S. Especially by Thursday, minimum RH within this type
of air mass should efficiently drop as low as 25-35%, perhaps
even locally lower. At this early juncture, surface winds should
be dropping off by Thursday, owing to the approach of a surface
ridge axis, but this timing will have to be watched for fire
weather concerns.

Fairly strong low-level cold advection is likely later Wednesday
into Thursday under a deep NW flow aloft over PA. This,
combined with clear skies and slackening winds in the overnight
hours will provide an ideal setup for radiational cooling.
Widespread frost is expected across much of Central PA, with the
exception of the southeast. Confidence in temperatures falling
below freezing across the northern tier continues to increase
and a Freeze Watch may be needed at some point. Temperatures may
be a degree or two colder on Thursday night as the surface high
remains centered over the northeastern United States.

By next weekend, the large-scale flow at least temporarily is
progged to amplify, with a building upper ridge axis over the
central CONUS and south-central Canada, and the potential for a
trough axis along the east coast. Clustering analyses with the
mid-level height fields show a piece of short-wave energy
topping the aforementioned and upstream upper ridge as holding
the key. One solution keeps this wave more progressive over
eastern Canada, with less troughing along the east coast and
drier weather for PA, while an alternate scenario digs this
same wave down into the Mid-Atlantic, with the potential for a
closed low along the coast and at least somewhat higher rain
chances for parts of the Commonwealth. Given relatively equal
model membership between these two scenarios, each are about
equally likely from this early vantage point, and thus we have
low chances (20-30%) for showers indicated.

&&

.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
Nice fall evening outside with warm temperatures and just a
few mid level clouds. For later tonight, there could be a
few showers across the far west, and lower conditions there.

Across the far east, some fog and lower CIGS by morning, given
return flow of higher moisture.

Left showers out of the central and eastern areas of central
PA for Tuesday, as the cold front is well west of the area until
late in the day. Timing of the front would support bulk of the
showers and perhaps an isolated storm with lower conditions is
after 00Z Wed.

Earlier discussion below.

VFR now, with the challenge mainly coming after the end of the
18Z TAF pkg (beyond 24hrs). A cold front will be dropping down
from the NW tonight and Tuesday, crossing Central PA on Tuesday
night. Showers will break out ahead of the front as moisture
advects in from the OH Valley. Clouds will invade from the W
through the night, and -SHRA will move into the wrn mtns
(BFD/JST/AOO/UNV) around or right before dawn. But, it looks
like a brief swing of warm advective rain, and it ends in only
an hour or two. This batch of rain could make IPT wet after
sunrise, but LNS and MDT will remain dry. BFD will have only a
short break before more SHRA and poss a TSRA move in for the
aftn. Most of the morning hours will be fair and cloudy over
the balance of the air space. SHRA and poss TSRA (20% chc - not
worth even a PROB30 at this point) will arrive in the aftn over
the wrn mtns, and become widespread as they spread to the west.
The next 24 hrs will be tough to pin down when these multiple
SHRA and poss TSRA will impact each specific airfield. The front
should be about halfway through PA at midnight, and should
clear LNS by 12Z (Wed).

Outlook...

Thu...AM fog then VFR.

Fri-Sat...AM fog, otherwise clear with VFR conditions.

&&

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

&&

$$

SYNOPSIS...Lambert/Dangelo
NEAR TERM...Lambert/Dangelo
SHORT TERM...Lambert/Dangelo
LONG TERM...Jurewicz/Bauco
AVIATION...Dangelo/Martin