Buttonwood, Pennsylvania Weather Forecast Discussion

662
FXUS61 KCTP 221947
AFDCTP
Area Forecast Discussion
National Weather Service State College PA
347 PM 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)
* Trending drier again for the beginning of October.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Mid-afternoon satellite imagery shows striking differences from
west to east across the state. A shallow deck of stratocumulus
are firmly in place across the eastern half of the
Commonwealth, characterized by stable conditions and
temperatures in the upper 60s to lower 70s. The western half of
the state is covered by much more textured clouds and a few
towering cumulus, associated with temperatures in the upper 70s
to lower 80s and MLCAPE around 1000 J/kg based on the latest SPC
Mesoanalysis.
A convergence boundary in western PA between stable southeast
flow east of the mountains and unstable southwesterly flow west
of the mountains has initiated scattered showers extending from
Somerset to Bradford early this afternoon. Hi-resolution
guidance supports the idea that these storms will fail to
maintain themselves with eastward extend as they approach
stable/cooler air.
Later this afternoon and into the evening, storms currently over
the Ohio Valley will lift northeastward into northwest PA. A few
storms could produce strong wind gusts where the best
combination of instability and shear (~30kts of 0-6km shear)
overlap. This region is also located at the SE edge of the DY1
SPC MRGL threat for SVR TSRA. Most locations east of I-99 and
south of I-80 should stay rain-free for the remainder of the
daylight hours today.
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.
Later tonight, a fairly potent shortwave trough will lift
through Central PA (most 850mb cyclonic vorticity model
guidance moves this wave through Central PA after midnight).
This wave should bring with it more widespread showers, though
still primarily located west of I-99 and north of I-80. The
severe threat should be lower with the loss of daytime heating.
Mostly cloudy skies continue tonight as lows stay quite mild in
the upper 50s to mid 60s. Rainfall totals by daybreak may
approach an inch in a few spots.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
A broad mid-level trough will remain over the region on Tuesday
and continue our stretch of unsettled weather. Destabilization
is likely on Tuesday afternoon in southeast PA where some
breaks in the clouds will generate a few hundred J/kg of CAPE.
Sufficient (20-30kts) of shear could support a few damaging wind
gusts in taller storms. SPC has painted a small Marginal Risk
for severe weather that clips the Lower Susquehanna Valley.
Highs Tuesday will reach the lower 80s in the southeast, while
staying in the upper 60s to lower 70s farther north and west.
By Tuesday night, upper level flow becomes more zonal and rain-
free conditions will persist. Light winds, ample surface
moisture, and some breaks in the clouds will support low
clouds/fog across much of the region into Wednesday morning.
Another mild night expected with lowers in the upper 50s to mid
60s.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
The long-term period will start out unsettled and then trend
quieter by the end of the weekend. On Wednesday, an upper low
centered over the Great Lakes will be accompanied by a very
positively tilted trough bringing warm/moist southwest flow into
the Commonwealth. That broad trough will rotate through
Pennsylvania through the end of the week, with multiple
shortwaves and associated enhanced rounds of convection along
it.
Periods of showers and storms are likely Wednesday afternoon
through Thursday evening as an approaching surface low moves
across the region. Widespread beneficial soaking rainfall of at
inch or more seems increasingly probable thanks to the multiple
rounds of rainfall expected. After a cold front moves through
later this week, wrap-around moisture in northwest flow could
lead to continued scattered showers.
By the weekend, a potent and quasi- zonal jet core across
southern Canada will sag south as a closed upper low across the
southern US drifts east. If the low stays south as the most
recent model guidance depicts, Pennsylvania will likely remain
rain-free for much of the weekend (perhaps dealing with some
clouds across southern PA). If the jet core across Canada (and
any associated fronts) trends farther south, or if the upper
low ends up drifting farther north, unsettled weather could
persist through the weekend.
&&
.AVIATION /19Z MONDAY THROUGH SATURDAY/...
More south to southwesterly winds this afternoon have allowed
some breaks and lifting of ceilings, though all but the western
most airfields (BFD/AOO/JST)remain MVFR. 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. Maintained a mention
for another round of showers later this evening and tonight with
highest chances again for BFD. Though coverage of showers looks
limited and light for most part. Look for ceilings to lower to
MVFR and possibly IFR tonight across the Alleghenies.
Outlook...
Tue-Sat...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...Banghoff
NEAR TERM...Banghoff
SHORT TERM...Banghoff
LONG TERM...Banghoff
AVIATION...Guseman/Gartner
CLIMATE...Steinbugl

NWS CTP Office Area Forecast Discussion