Swartzville, Pennsylvania Weather Forecast Discussion

771
FXUS61 KCTP 180251
AFDCTP
Area Forecast Discussion
National Weather Service State College PA
1051 PM EDT Wed Sep 17 2025
.SYNOPSIS...
* Waning showers and cloud cover tonight in southeast PA as a
  surface low gradually moves east of the region.
* Widespread valley fog expected early Thursday morning as high
  pressure and dry weather builds in for the end of the week.
* Still dry, but slightly cooler with a refreshing fall-like
  airmass this weekend before temperatures trend above average
  next week - not much rain in sight.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
A slow-moving coastal low will move off the NJ coast tonight,
with northeast to northerly flow in its wake. Lingering low
clouds across southeast PA along with a stray shower or two will
persist tonight before clearing out early Thursday morning.
Farther northwest, clear skies and calm winds underneath
building high pressure will support some valley fog tonight.
Dewpoints dropped quite a bit lower than expectation across much
of central and northern PA today owing to less cloud cover than
expected, which could limit the extent of fog to some extent.
Lows tonight will range from the mid 40s in the typical cool
spots in northwest PA to the low 60s in the southeast where
clouds will hang on for much of the night. Most of the area,
though, will see temperatures in the mid 50s by daybreak on
Thursday.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY/...
Thursday and Friday will be a continuation of what we`ve seen
for a majority of the past couple weeks with plenty of sunshine,
seasonably mild temperatures, and light winds. It will take a
little while for the moisture in southeast PA to be replaced by
a drier airmass, so expect the air to feel a bit humid still on
Thursday. Highs will generally be in the 80s with lows in the
upper 40s (NW) to lower 60s (SE). A backdoor, moisture-deprived
cold front will sag south into northern Pennsylvania Friday
afternoon, with an increase in cloud cover north of US-6 being
the only noteworthy aspect of its arrival. Drier air awaits in
its wake...
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Friday night - the aforementioned backdoor cold front will
slide through Pennsylvania with a strong 1028mb high surging in
behind it. Dewpoints will plummet by Saturday morning,
supporting a return to below-normal overnight temperatures with
clear skies and calm winds. Surface high pressure will set up
off the New England Coast for the weekend, ensuring moist
southeast flow and tranquil weather. Highs will tick down a few
degrees for the weekend, with highs in the 70s and lows in the
50s most likely at this time.
Heading into next week, high pressure will begin to lose its
grip on the region as an upper trough tries to disrupt the
persistent ridge of high pressure aloft. Still plenty of
uncertainty on how much, if any, precipitation will get into
Pennsylvania, but southerly flow ahead of the approaching
system will support continued warmer than average temperatures
for the start of Astronomical fall.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
Scattered showers across eastern Pennsylvania will gradually
fade over the next couple of hours with no impacts outside of a
sprinkle expected at LNS. Confidence in -SHRA at LNS remains too
low to include in the 00Z TAF package based on current radar
trends/recent model guidance due to the scattered nature of
remaining showers.
Slightly more cloud cover this evening could limit earlier fog
projections, with recent RAP/GLAMP guidance scaling back on fog
mentions overnight. The western terminals (BFD/JST/AOO) will
have the highest chances of clear conditions overnight, which
will allow for some formations; however, this looks more limited
to valley locations at this time. Have progged IFR/LIFR
restrictions at AOO based on recent GLAMP/HREF probabilities
with moderate (50-60%) confidence; however, lower confidence
(20-30%) at BFD/JST in fog reaching into the airfield between
07-11Z Thursday. While model guidance does outline lower chances
for IPT/MDT/LNS clearing out, increased low- level moisture
coupled with easterly flow will retain some threat for fog/low
stratus potential; however, low confidence in this occurring as
of the 00Z TAF package.
Coastal low continues drifting east of the area with widespread
clearing expected after 12Z Thursday. Any fog/low stratus
development could linger through until ~14Z Thursday; however,
lower confidence in where this fog will develop as of 00Z
Thursday. Widespread VFR conditions are progged by all model
guidance after 14Z/15Z through the end of the TAF period.
Outlook...
Fri-Sun...VFR with AM valley fog.
Mon...Slight chance SHRA/PM TSRA possible across NW PA.
&&
.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/Banghoff
NEAR TERM...Lambert/Banghoff
SHORT TERM...Lambert/Banghoff
LONG TERM...Lambert/Banghoff
AVIATION...NPB
CLIMATE...Steinbugl

NWS CTP Office Area Forecast Discussion