Andrews Bridge, Pennsylvania Weather Forecast Discussion

522
FXUS61 KCTP 221134
AFDCTP
Area Forecast Discussion
National Weather Service State College PA
734 AM EDT Mon Sep 22 2025
.SYNOPSIS...
* Above average temperatures for the last week of September to
  begin astronomical Fall
* Periods of much needed rainfall expected today (western half
  of PA) through Thursday (expanding across Central and Eastern
  PA
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Widespread stratus and strato cu clouds continue to blanket the
vast majority of Central PA including the Susquehanna Valley,
Western Poconos and Laurel Highlands.
A weak, compact shortwave lifting NE across West-Central PA
through the mid morning could give some locations about 15-30
minutes of rain, While most locations in Central and SE PA see
little or no rainfall at all through Wednesday.
Most hires model data indicates that the bulk of the showers
will be across the NW Mtns through the mid morning hours today,
before gradually spreading into the Central Ridge and Valley
region this afternoon and evening.
The greatest chances for rain/showers during the near term
term period will be early today across the NW Mtns and again
late this afternoon and evening (across the NW zones along a
NEWD lifting warm frontal zone, SE edge of a band of 1.5+ PWATS
and swrly LLJ axis). That portion of the state resides at the
SE edge of the DY1 SPC MRGL threat for SVR TSRA.
High temps during the mid to late afternoon hours will be in the
low to mid 70s across the northern and western mtns and upper
70s to low 80s throughout the Central and Southern Valleys.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
High pressure and slightly lower PWATs to the east will keep
any rain showers to a minimum east of I-99 and south of I-80.
High temps this afternoon will range from the mid 70s over the
higher terrain of the north and west, to the upper 70s and
around 80F elsewhere.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
* The clarity of weekend forecast has improved (as we`d expect
  getting closer in time). Even yesterday, tremendous
  uncertainty surrounded the northern extent of precip from a
  much stronger closed low that was detached across the Central
  and Eastern U.S. from a strong zonal jet across Southern
  Canada.
The latest 00-06Z model runs have highlighted a further south
northern stream jet core and a well-defined, potent shortwave
(aka - kicker) that will shunt the aforementioned Eastern U.S.
trough and associated precip east to the Atl coast by early
Friday night with a weak ridge of sfc high pressure over PA on
Saturday accompanied by variable amounts of cloud cover at
various levels.
Previous Disc...
A +tilt upper level trough and llvl frontal boundary will move
southeast from the Great Lakes bringing the best odds for rain
particularly on Tuesday focused across the northwest 1/2 of
central PA.
First will be the development of a slow moving closed low
as we head into the middle of the week acrs the Central Plains
and Mid Miss valley as a significant jet max/potent short wave
dives SE across the Central and Northern Rockies. The timing of
this feature`s trip across the Ohio Valley, Central Appalachians
and Mid Atlantic Region should be mainly in the Wed through Fri
night period. The second feature of concern is the timing and
amplification of a northern stream upper shortwave within the
potent and quasi-zonal jet core across southern Canada.
Yesterday`s model runs phased the timing of the northern and
southern stream troughs better and caused the southern
trough/closed low to be a few hundred NM further south. After a
12Z Sat - 00Z Sun pair of runs that became more unphased with
this feature and allowed it to drift north into flat ridge over
southern Ontario and SW Quebec, the timing of the northern
stream trough appears to be more a kicker and once again
suppresses the southern low a bit more south with faster
movement across the Eastern U.S.
Based on this, the greatest probability for rain will reside in
the late Wed through Friday evening period. Lingering, scattered
showers appear to be the outcome for later Friday night and
Saturday.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
Southeast winds will continue to push moisture to the northwest
this morning. Ceilings have scoured out a bit out west nearer
a band of showers moving through, but still expecting
widespread MVFR ceilings through a good deal of this morning.
As winds shift a bit more south to southwesterly today,
ceilings should come back up to VFR early this afternoon.
Kept prevailing SHRA chances at BFD where the greatest
confidence is for rain, along with VCSH at JST and PROB30s for
TSRA/CB at both sites later this afternoon into early this
evening. Introduced a mention for another round of showers later
this evening and tonight with highest chances again for BFD.
Look for ceilings to lower to MVFR and possibly IFR tonight
across the Alleghenies.
Outlook...
Tue-Fri...Multiple rounds of SHRA and PM TSRA (best chances Tue
and Thu) with sub-VFR conditions possible.
&&
.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/Bowen
LONG TERM...Lambert/Steinbugl
AVIATION...Guseman/Martin
CLIMATE...Steinbugl

NWS CTP Office Area Forecast Discussion