381
FXUS61 KCTP 160925
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
525 AM EDT Thu Oct 16 2025

.SYNOPSIS...
* Seasonably cool days and crisp Autumn nights through Friday
* Modest warming trend/above average temperatures this weekend
* Weekend starts dry and ends wet: breezy/windy conditions and
  locally heavy rain showers probable Sunday into Sunday night

&&

.NEAR TERM /THROUGH TONIGHT/...
Mostly sunny and seasonably cool/breezy today. Max temps in the
low 50s to low 60s are near to several degrees below mid
October climo. Daytime dryness will peak this afternoon with
minRH in the 25-35% range. P-gradient and strong northerly llvl
flow between exiting storm in the North Atlantic and high
pressure migrating to the southeast from the Upper Great Lakes
will result in 20-30 mph wind gusts focused over the eastern
portion of the forecast area.

Minimum temperatures will reach a short term nadir overnight
with frost/freeze conditions probable across the majority of CPA
early Friday morning. Fcst low temps range from 25F in the
usually colder spots in the NW Alleghenies to around 40F in the
Harrisburg metro. Frost advy has been issued for the 7 zones in
the LSV where the growing season remains active. A persistent
light NNW breeze raises some concern for frost formation
especially in the eastern periphery of the CWA adjacent to PHI,
but overall risk/confidence is high enough to issue particularly
for the valley locations and sheltered rural/agricultural areas
(outside of the larger cities and towns) that should experience
the coldest temperatures.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
Sfc ridge axis migrates slowly eastward Friday reaching eastern
PA by 12Z Saturday. This should allow for one more chilly night
particularly in the eastern/northeastern valleys. Max temps are
neutral to slightly warmer day/day with fcst highs 55-65F. High
to mid level clouds will steadily increase from west to east
Friday night into Saturday as WAA pattern ramps up heading into
the weekend.

500mb ridge axis shifts to the east on Saturday with milder air
surging into the area behind an increasingly strong SSW 850mb
LLJ. Lead perturbation in the Upper OH Valley could trigger some
showers across western/northwestern PA early on Saturday in the
vicinity of lifting warm front. Otherwise, it will be a dry
and milder start to the weekend with highs +5-10 degrees warmer
vs. Friday.

Amplifying 500mb trough digging into the mid MS/lower OH valley
Saturday night will send a deepening/seasonably strong
sub-1000mb sfc low into lower MI by 12Z Sunday. Low level wind
fields strengthen in-kind and advect hi pw air >1" northeastward
from the Gulf. Blended model guidance favors increasing odds for
rain showers over the NW 1/2-1/3 of the forecast area overnight
Saturday through early Sunday morning. Noticeably milder readings
Saturday night with low temps trending +7-15 degrees warmer vs.
Friday night thanks to increasing clouds and southerly flow.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
16/00Z model guidance still not in full agreement concerning the
evolution of the sharpening/negative tilted upper trough pushing
east from the Great Lakes/Ohio Valley Sunday into Monday. The EC
remains the most amplified solution, showing a deep 500mb cut-
off low over PA by 12Z Monday. The GFS is much flatter and more
progressive with the CMC clustering closer to the GFS albeit a
tad stronger/farther south.

As the pattern details are ironed out with time, there are some
signals flashing for potential isolated svr storm/heavy rain
threat Sunday-Sunday night. The tightening p-gradient and strong
llvl wind fields with this system will also bring breezy/windy
conditions which could easily blow around unsecured objects
including Halloween decorations.

At a minimum, rain showers should linger into Monday followed
by a drying trend Monday night into Tuesday. Time of arrival of
the next frontal system for Tue-Wed also in question and is
largely dependent on the speed/departure of the Sun-Mon system.
EC is again on the deep end of the guidance envelope; max POPs
into midweek are painted across the western & northern mtns.

&&

.AVIATION /09Z THURSDAY THROUGH MONDAY/...
515 AM update.

Winds have weaken overnight, but expect winds to quickly pick
back up shortly after sunrise.

Otherwise not really much change. Had updated BFD earlier, tiny
area of lower clouds there earlier.

Earlier discussion below.

Winds kicking up at times since I came in at 1130 PM.
Adjusted the fcst for this. Also the evening forecaster had
LLWS in for some eastern areas.

Anyway, expect clear skies with VFR conditions today into
Friday. Main issue today will be gusty winds once sun is up
here this morning. Main change was to go a bit stronger with
the winds than the 00Z TAF package had, or the guidance.

This based on the pressure gradient being a bit stronger today,
than earlier. Winds will once again weaken some after sunset
today.

Next chance for widespread showers will be Sunday, as a cold
front nears the area.

Outlook...

Fri-Sat...VFR.

Sun-Mon...Restrictions possible in SHRA. Low probability of a
thunderstorm over northwest PA.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Frost Advisory from 2 AM to 9 AM EDT Friday for PAZ036-057-059-
063>066.

&&

$$

SYNOPSIS...Steinbugl
NEAR TERM...Steinbugl
SHORT TERM...Steinbugl
LONG TERM...Steinbugl
AVIATION...Martin