913
FXUS61 KCTP 231124
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
724 AM EDT Sat Aug 23 2025

.SYNOPSIS...
* Scattered showers/storms this aftn/evening over the Alleghenies
  in the warm sector.
* Cold front sweeps through Sunday/night with more storms.
* Canadian high pressure will bring many dry days next week with
  temperatures below normal.

&&

.NEAR TERM /THROUGH TONIGHT/...
No fog quite yet, but the high clouds spilling over the
flattening ridge are starting to obscure our view of the llvl
clouds/fog. We still expect some valley fog in the nrn mtns this
AM, but certainly not as widespread as Fri AM. Dewpoints are
going to creep up a little with the srly wind already in effect.
moisture will build up enough and the higher terrain of wrn
PA/Allegheny mountains will supply triggers. Modest lapse rates
aloft should keep a majority of the deeper convection without
thunder this aftn. Coverage in the 20-30pct area will
necessitate low chc/sct PoPs there. Without triggers in the
east/southeast, no convection should get deep enough to make
rain. Temps s/b extremely similar to Fri.

&&

.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
Forcing will be enhanced tonight due to a shortwave trough
aloft pressing in from the west. This should help to organize
the sct SHRA/TSRA this evening over the central mtns and help
them push east overnight. PoPs through the rest of the night
will still be <20pct over Lancaster Co and 20s in the next tier
of Cos to the NW. 60-70pct chcs will cover the central and
western mtns. Look like we`ll be back in between vort maxes on
Sunday, so there will probably be a little lull in the precip or
at least sparse convection during the middle of the day. But, by
late aftn, the temps get warm enough and dewpoints much higher
(in the SE) vs Sat that the radar should start to fill in during
late aftn/early evening. The cold front should be about halfway
thru the CWA by midnight Sun night. The last of the storms
should be off to the east around sunrise Mon. At this point, SPC
is not impressed with the atmos over PA to only mention in the
Day2 outlook reasons why the storms should not severe. There
could be a stronger cell or two grow up since the NAM generates
1000-1500 CAPE and 30+ kts of deep layer shear. The GFS is less
impressive with lower CAPE and shear numbers across the board.
So we`ll have to keep vigilant Sun/night for a stronger storm or
two. WPC ERO does put us into the MRGL area, but this may be
overdone with QPF over two days barely an inch in a few pixels
on the grids. Most common QPF values over the 48hrs from this
aftn thru Mon AM are only 0.3-0.6". Due to ongoing AM convection
Sun and more cloud cover through the day, our maxes should be
a little cooler than Sat. Mins Mon AM behind the cold front and
in a little clearing before some low clouds/shallow convection
arrives in the early morning hours, BFD could dip near 50F. That
will probably make some fog Mon AM since the wind won`t be >5kt
for most of the night.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
W/NW flow across LE on Mon-Tues and cool air from Canada will
generate sct lake effect...rain showers. These could linger into
Wed, but will be getting very isold Tues night as CAPE gets very
small thanks to the cap in the 5-8kft range. Enough CAPE exists
on Mon that there could be a ltg strike or two. Temps are much
cooler next week. Expect highs about 5-15F cooler than normals.
Wed night looks like the coldest night with lows in the 40s all
over the NW 2/3rds of the CWA. PoPs don`t return before the end
of the long range period (next Fri).

&&

.AVIATION /11Z SATURDAY THROUGH WEDNESDAY/...
Low cloud just slid into IPT, but it should mix away very
quickly. Felt it was necessary to mention it in the TAF, esp
considering the big event they have in (South) Williamsport this
week/end. There may be increased traffic and some of those
pilots may not know the local terrain that becomes hidden in
LIFR.

The T-Td spread should keep the cu bases this aftn above 3kft,
so any reductions in flight categories would be due to
precip/rain. Showers will pop up over the Allegheny
ridges/plateau. The terrain will be a major factor in where they
pop up today. Coverage of the showers will be only 20-30pct at
any one time, but there will be many, so we`ve mentioned
SHRA/TSRA in PROB30 and TEMPO mentions for now without a better
confidence on when & where the showers will be. A few of the
showers will grow tall enough to produce ltg. But, those will
be the exception and not the rule.

Showers will not get into the Lower Susq until very late
tonight (aft 06Z), if at all. Forcing due to a healthy short
wave trough aloft will aid in organization of the SHRA/TSRA for
the second half of the night. Sunday will hold more widespread
SHRA/TSRA, but the early convection and assocd clouds/cooled air
may help hold them from being strong. The cold front pushes
across from W-E through Sun night, clearing things out by
sunrise Mon.

Outlook...

Mon-Wed...SCT SHRA/MVFR for BFD. VFR elsewhere.

&&

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

&&

$$

SYNOPSIS...Dangelo
NEAR TERM...Dangelo
SHORT TERM...Dangelo
LONG TERM...Dangelo
AVIATION...Dangelo