775
FXUS61 KCTP 301110
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
710 AM EDT Tue Sep 30 2025

.SYNOPSIS...
* Very warm to close out September followed by a brief cool down
  Wednesday and Thursday
* Potential frost and freeze conditions, mainly across the
  Northern Mountains Wednesday night and early Thursday morning
* Our building string of dry days will likely extend for another
  week to 10 days

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Minor changes to increase cloud cover amount this morning for
the extensive area of altostratus and cirrostratus streaming in
an anticyclonic arc across the SE 2/3rds of the CWA.

Also trimmed sfc Tds/RH values slightly for the next 3
afternoons, blending in NBM25pct values.

Cloud cover kept the majority of the CWA quite mild overnight
with temps just prior to daybreak in the mid 50s to low 60s
across the southern half of PA with upper 40s to low 50s found
over the Northern Mountains. These values are 5-10 deg F above
normal for the last day of September.

This month will end on a warm note with the aforementioned
shield of mid and high clouds slowly thinning out from the north
during the midday and afternoon hours. High temps today will be
in the mid 70s across the higher terrain of the north and west
and in the upper 70s to low 80s in the Central and Southern
Valleys.

The passage of a dry/backdoor cold front late today/this evening
will usher in seasonably cooler and drier air on a steady,
5-10kt breeze from the N/NE.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
Under clear skies tonight, temps will average 5-10 degrees
cooler than Monday night with mins ranging from the upper 30s
across the northern tier to the low 50s in the Lower
Susquehanna Valley. A few of the perennial cold spots across
Mckean and Potter counties could see mins in the mid 30s with a
touch of light frost.

October will start with seasonably strong 1032+mb Canadian HP
drifting southeast from Hudson/James Bay into northern New
England. The cooler and drier llvl flow from the N/NE will bring
a noticeable cool down for Wednesday and Thursday.

Afternoon highs on Wednesday will turn out to be 5-10 degrees
lower vs. Tuesday...in the low 60s/70s.

Clear and cooler temps for Wednesday night with a high
confidence for frost/freeze over northern PA, given diminishing
wind, low dewpoints and min temps in the low to mid 30s. GFS
MOS guidance shows 33F for Bradford at sunrise Thursday, which
highlights the fact that and anomalously dry airmass underneath
high pressure this time of year can yield under-performing
temperatures.

A Freeze Watch may be needed for portions of northern PA in the
next 24 to 48 hours, and frost is nearly a sure bet for a
stripe of counties along the PA/NY border at this point.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
Slow moving and blocky pattern under deep layer ridging over
the Mid Atlantic and Northeast states will lock-in the renewed
run of dry wx through the first weekend of October. NBM/WPC QPF
is 0.00" in CPA for the next 7+ days.

Thursday night also looks chilly with some frost possible again
over the northern tier. As high pressure moves just each of the
region later this week, southwest flow will usher in slightly
milder temperatures each day. Temperatures moderate back to
well-above normal by the second half of the weekend. Calm winds
combined with clear skies and a gradual uptick in surface
moisture will likely lead to daily occurrences of fog in the
typical river valleys across northern PA. The return of the
multi- day/persistent parched pattern could offset any short
term improvement in the low-end drought conditions from much
needed/beneficial rainfall last week.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
A few areas of patchy fog have developed overnight, but
categorical flight restrictions should lift and improve quickly
over the next hour. Clouds will slowly clear out from northwest
to southeast during the day today as the tropical storm begins
to pull away from the coast of the southeastern US. Winds will
be out of the north-northeast at 5 to 10 knots. Drier air is
expected to take over in the low levels tonight, making fog
formation probabilities at TAF sites less than 20% even under
the clear skies and radiational cooling.

Outlook...

Wed-Fri...Predominantly VFR.

Sat...Patchy AM fog, especially southeast PA.

&&

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

&&

$$

SYNOPSIS...Lambert
NEAR TERM...Lambert/Dangelo
SHORT TERM...Lambert
LONG TERM...Steinbugl/Banghoff
AVIATION...Bauco/Bowen