Spring Glen, Pennsylvania Weather Forecast Discussion

954
FXUS61 KCTP 200900
AFDCTP
Area Forecast Discussion
National Weather Service State College PA
500 AM EDT Sat Sep 20 2025
.SYNOPSIS...
* Above average daytime temperatures to close out astronomical
  summer 2025
* Trending mostly cloudy by the end of the weekend with rain
  most likely starting our across the northwest Mountains Monday
  afternoon or evening, then spreading across the remainder of
  Central PA late Monday night and Tuesday.
* a few periods of scattered showers expected Wednesday through
  Friday with Saturday showing showery conditions persisting
  based on the US GFS and Canadian guidance, while and the
  European and German models indicate dry conditions with a
  fair amount of sunshine and a light breeze out of the north.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Sfc cold seen pushing south of KIAD/KCBE line per fine line on
dual pol reflectivity from KLWX. Limiting 925 mb streamline
with a longer over-water fetch of llvl/Atlantic moisture from
the ENE was seen veering slightly and helping to form some bkn,
high- based strato cu across the Lower Susq Valley and Scent
Mtns early today. Elsewhere across much of Northern and Western
portions of our CWA, clear skies prevailed under a light ne flow
with high pressure centered over SW Quebec Canada.
08Z temps range from the upper 40s over northern PA where PWAT
values were under 0.50 of an inch to the low 60s across
southern PA with PWATs of 1.0+.
Cloud cover will come in the form of a shallow sct-bkn layer of
040-060 strato cu across the SE 1/4 to 1/3 of our CWA with
sunshine mixing with a bit of cirrus late this morning and this
afternoon in the west.
Afternoon max temps today will display about a 10 deg F range
from north (70F) to south (80F) across the CWA.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
Low clouds are forecast to develop tonight into early Sunday
morning in association with an increasingly moist ESE upslope
flow.
Locally dense, east-facing slope/ridgetop fog and widespread
low stratus signal is now showing up in the hires model QPF
field and "goal-post" fcst soundings.
The cloud cover and moist easterly flow will certainly result
in a milder minT trend with fcst lows about +10F warmer across
the northern half of the fcst area vs. Friday night/AM Saturday.
The cool air damming pattern on Sunday suggests some downside
to max temps depending on breakup/mixing out of morning low
clouds.
The greatest chance for rain/showers during the period will be
late Sunday night into early Monday across the NW zones along a
NEWD lifting warm frontal zone and LLJ.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
Strong sfc high shifts to the Northeastern Seaboard early next
week. This will allow a +tilt upper level trough and llvl
frontal boundary to move southeast from the Great Lakes bringing
the best odds for rain particularly on Tuesday focused across
the northwest 1/2 of central PA.
A lot of uncertainty in the guidance regarding a possible Omega/
blocking pattern setting up over the CONUS by the middle of
next week with cutoff low in the Central U.S. This opens up
plenty of downstream solutions and outcomes for both precip and
temperatures. NBM data indicates a gradual cooling trend back to
within a few degrees of the historical average (highs 65-75) for
the end of September by the end of next week.
&&
.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
VFR conditions appear virtually certain (~100%) with all model
guidance indicating the current low-to-mid level deck across
southwestern Pennsylvania decaying overnight and allowing for
clear skies. Current T/Td spreads, coupled with recent GLAMP
guidance indicated some valley fog will possible across the
deepest valleys of northern Pennsylvania but generally do not
expect any restrictions at BFD overnight. Scattered showers will
be possible towards the end of the TAF period across the
Laurels; however, too uncertain in terms of adding mentions in
the 00Z TAF package as best signals appear west of the area.
Outlook...
Sun...MVFR/IFR cigs likely; trending MVFR/VFR by Sunday
afternoon.
Mon-Wed...Rain showers possible; best odds over the NW 1/2 of
the airspace.
&&
.CLIMATE...
Astronomical fall officially begins with the autumnal equinox
on Monday, September 22, 2025 @ 2:19 p.m. EDT. The Autumn 2025
season will last 89 days, 20 hours, and 43 minutes. Daylight
saving time will end just after Halloween with clocks falling
back at 2 a.m. Sunday, November 2, 2025.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Lambert/Steinbugl
NEAR TERM...Lambert/Steinbugl
SHORT TERM...Lambert/Steinbugl
LONG TERM...Lambert/Steinbugl
AVIATION...NPB
CLIMATE...Steinbugl

NWS CTP Office Area Forecast Discussion