Middlesex, Pennsylvania Weather Forecast Discussion

920
FXUS61 KCTP 040209
AFDCTP
Area Forecast Discussion
National Weather Service State College PA
1009 PM EDT Fri Oct 3 2025
.SYNOPSIS...
* Dry with well-above average temperatures this weekend and
  into the beginning of next week.
* Cold frontal passage brings showers on Tuesday/Wednesday.
* Dry conditions again later next week with low temperatures
  approaching the freezing mark in the northern tier and colder
  valleys of central PA.
&&
.NEAR TERM /THROUGH SATURDAY/...
Fog is expected to form in the valleys tonight - not widespread,
but more than Fri AM. The West Br and tribs to it have the best
chc of having fog overnight. Temps should stay just 3-5F milder
than the prev night but dewpoints will also be a notch higher.
Coldest spots will dip to around 40F, and most will be 45-50F.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH 6 PM SATURDAY/...
WYSIWYG. More of the same Sat. After fog goes away: sunny and
very warm for Oct. 8H temps of +12-15C will mix down to hit 80F
over half the land mass of Central PA. Those are more like late
June or early Aug highs. The higher elevations stay below that
mark. Records are generally 5+F greater than the forecast highs,
though. GFS is much weaker with the inversion than NAM. The
weak inversion is a good signal for a dewpoint bomb/drop during
the day. But, without support from NAM and HREF mean, don`t want
to go too wild with a departure from guidance. But, did nudge
mid- day/aftn dewpoints down a few degs from NBM, esp in the
mtns and Lower Susq.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
The dry and warm pattern through Monday will give way to the
next opportunity for rain by Tue-Wed as surface low pressure
from the central US tracks northeastward into Ontario. The low
will drag a cold front through the area, bringing some rainfall
to central Pennsylvania.
While there should be decent moisture return ahead of the front,
with PWAT values rising to the 1.25-1.4 inch range (~90th
percentile for this time of year), there is still some
uncertainty as to just how much rain will fall. Ensemble mean
QPF is generally around 0.50 inch in northwest PA, with lesser
amounts as you move south and east, but some of the
deterministic guidance, namely the 12Z GFS, continues to show
the potential for over an inch of rain over parts of central PA.
This does not appear to be the most likely solution at this
point, however, as most guidance shows the best synoptic scale
forcing passing well to our north and more detached from the
tropical moisture stream. Additionally, weak instability should
help to limit rainfall rates.
All guidance shows high pressure building into the region at the
surface and aloft in the wake of the cold front. This setup
would allow for another spell of dry weather into the latter
half of the week. With a 1030 mb surface high expected to be
centered over the region Wednesday and Thursday nights, ideal
radiational cooling conditions are anticipated with mainly
clear skies and light winds. Temperatures will fall into the 30s
and 40s both nights and frost formation is likely over the
north and west. There is also some potential for temperatures to
drop below freezing Wednesday night across the northern tier and
colder valleys of central PA.
&&
.AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
Looking at clear skies overnight into Saturday, as high pressure
remains over the area. The combination of light winds, low PW
values, and clear skies may result in a little fog in spots, but
the airmass is quite dry, so any fog will be limited.
For the 00Z TAF package, went close to what the 18Z package with
regard to the location and timing of the fog.
Earlier discussion below.
Expect fog to form in the valleys, likely more widespread than
Fri AM. Have mentioned IFR fog for a few hours at IPT (most
likely) and AOO, but UNV has much lower chc (20%) of dipping to
IFR. Still mentioned it there, though. BFD may get a little fog
in the late evening/early night, but probably go back to VFR
for the balance of the night as the coldest air slides off into
the deep valleys nearby. Sat will be VFR after the fog (and any
little bit of low stratus near the fog) dissipates. The center
of the sfc high will be close enough to keep the wind very light
and out of the S/SW again. More of the same for Sun and Mon.
Outlook...
Sun-Mon...AM Fog (Mainly N PA); otherwise VFR.
Tue...Sct SHRA.
Tue PM...CFROPA. SHRA. TSRA poss. IFR fog poss mainly NW.
Wed...Sct AM SHRA SE. Otherwise becoming VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Dangelo/NPB
NEAR TERM...Dangelo/Colbert
SHORT TERM...Dangelo
LONG TERM...Colbert/Bauco/NPB
AVIATION...Dangelo/Martin

NWS CTP Office Area Forecast Discussion