428
FXUS61 KCTP 171315
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
915 AM EDT Fri Oct 17 2025

.SYNOPSIS...
* Seasonably cool and dry conditions continue today under a
  ridge of high pressure
* A modest warming trend and above average temperatures this
  weekend
* The weekend starts dry and ends wet: breezy/windy conditions
  and locally heavy rain showers probable Sunday into Sunday
  night with a chance of a gusty thunderstorm

&&

.NEAR TERM /THROUGH TONIGHT/...
After a crisp and frosty start today, expect sunny to partly
cloudy conditions this morning into the afternoon with clouds
spilling southward around an eastward migrating upper level
ridge over the Great Lakes. Clouds continue to lower/thicken
through tonight as warm advection ramps up. Showers are possible
over NW PA late near the intersection of southwest LLJ and warm
front. Max temps today will be steady to slightly higher/warmer
compared to Thursday with highs in the 55-65F range.

&&

.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
Sfc ridge axis migrates slowly eastward and reaches eastern PA
by 12Z Saturday.

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 with a shot of low to mid level warm
advection/uvvel (ahead of the sfc warm front) could trigger
some showers across western/northwestern PA early Saturday.

Otherwise, it will be a dry and milder start to the weekend
with highs +5-10 degrees warmer vs Friday. With gusty southerly,
then nwrly winds coming Sunday and Monday respectively, it will
be advantageous to get any leaf peeping activities done on
Saturday before significant leaf off occurs.

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 THURSDAY/...
In terms of the system on Sunday, there remains quite a bit of
uncertainty at this time horizon with regards to any
severe/flash flooding threat. Presence of a mid-level trough
and cold front across the region will provide ample lift with
favorable shear in place. The biggest uncertainty with regards
to the severe threat will remain instability. Lingering
precipitation ahead of the frontal passage will lower
instability and severe threat; however, if higher instability
ends up panning out, some severe threat Sunday afternoon and
evening across central Pennsylvania. In terms of flash flooding
risk, thunderstorms will bring about some potential for locally
heavy downpours with PWATs approaching the 90th percentile
across NW PA. That being said, area under the gun for heavier
rainfall are currently under D2 drought so a longer-duration
rainfall might trend more beneficial, thus would need heavy
rainfall to fall in a very quick timeframe to cause widespread
issues.

As the system shifts east, 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. Regardless, signal for a wet pattern over the
next week should continue to mitigate major concerns for fire
weather in the near-term.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
Confidence is high (>90%) of VFR conditions continuing through
the entire forecast period. No fog or restrictions to visibility
occurred this morning. Local radar wind profiles do indicate
low level winds above the inversion around 30-35kts near KLNS so
added LLWS for the short term.

Otherwise, a shield of high cirrus crossing the Great Lakes will
move over the region through the day and overnight, but there is
limited threat (<10%) that ceilings would lower to less than
FL100 much later in the period.

Surface winds will increase by 15Z as sunshine helps mix down
winds around 5,000 ft. These will diminish around sunset.

Outlook...

Sat...VFR. A few showers possible over northwest PA.

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

Tue...Lingering showers.

&&

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

&&

$$

SYNOPSIS...Lambert/Steinbugl/Banghoff
NEAR TERM...Lambert/NPB/Steinbugl
SHORT TERM...Lambert/Banghoff/NPB
LONG TERM...Banghoff/NPB
AVIATION...NPB/Tyburski