Duboistown, Pennsylvania Weather Forecast Discussion

901
FXUS61 KCTP 100222
AFDCTP
Area Forecast Discussion
National Weather Service State College PA
1022 PM EDT Tue Sep 9 2025
.SYNOPSIS...
* A mainly dry, seasonable weather pattern is expected to
  continue into next week
* The lone and relatively minor weather impact will be a deck of
  stratus clouds that will move westward from the Mid Atlantic
  coast and spread across the Lower Susquehanna Valley and
  Southwestern Poconos.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
Western edge of cirrostratus was brushing our far SE zones this
evening with the leading edge of stratus almost peeking out from
underneath it as it moves westward with the increasing easterly
925-850 mb mean flow off the Western Atlantic.
Latest RAP guidance supports the fact that our gridded cloud
data isn`t nearly bullish enough on both the sky cover
percentage and the western extent of the clouds late tonight
through Wednesday.
Included 20 pops for --RA when in fact there could be more
definite occurrence for drizzle (that may...or may not measure).
ENE over-water upstream fetch off the Atlantic (in the 925-850
mb layer) persists for our Lower Susq Valley zones through all
of Wednesday as the sfc-850 mb low moves from ESE of KILM late
this evening, to several hundred KM east of KORF at 22Z
Wednesday. Periods of higher based, BKN stratocu/stratus could
make it to the Scent Mtns and up to KSEG during the daylight
hours Wednesday. The flow in this layer gradually backs to the
NE, helping to push the sharp northern edge of the low clouds
gradually to the south late Wed/Wed night.
Otherwise, initially clear skies over the Central and Western
part of PA, will allow for optimal radiational cooling with
patchy large stream/river valley fog between about 08Z-13Z Wed.
Slight air mass modification should result in overnight lows
being several degrees above those of last night. Thus, we expect
little to no frost formation.
Coolest max temps Wed will be found across the SE zones where
some places will only see the mercury reach the upper 60s,
whhile abundant sunshine over the rest of the fcst area will
lead to highs in the low-mid 70s.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/...
A drying air mass and sinking motion just above the boundary
layer is expected to settle across the Commonwealth Wednesday
night and Thursday, resulting in mostly clear/sunny skies. Areas
of river valley fog should develop again late Wednesday night
into early Thursday.
A dry, seasonable air mass will continue to support 70s to near
80 for daytime highs, with upper 30s (coldest northern valleys)
to around 50 (parts of southern PA) at night.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
On the large-scale, our ensemble prediction systems continue to
indicate a fairly blocky upper-level pattern into next week,
with a mean upper ridge axis through the central CONUS and
south-central Canada, with a general weakness in the upper
height fields across the upper Great Lakes and the northeastern
states. Despite the troughy nature of the upper levels over PA,
a very dry air mass overall (thanks to confluent NW flow aloft
promoting surface high pressure development) points to a high
likelihood of continued rain-free conditions for the
Commonwealth.
Looking at the latest cluster analyses in DESI, an earlier
"split scenario" (relatively equal weighting/probabilities of a more
amplified wave and better rain chances for PA vs. an open,
progressive, farther north evolution with less rain chances for
PA) with handling of an upstream short-wave coming into the
Great Lakes region Sunday-Monday is trending towards more
weighting/higher probabilities for the latter/drier scenario.
Thus, NBM POPs have reasonably edged lower for the end of the
weekend into next week.
&&
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
VFR conds will continue overnight for the central and western
areas.
After 06Z, easterly flow off the Atlantic will usher in a lower
level stratus deck into the Lower Susq Valley overnight. The
HREF model suggests a 70+% probability of LNS and MDT seeing
cigs dip to MVFR.
Farther to the west, where skies remain mainly clear, we could
see valley fog develop in the pre-dawn hours on Wednesday. Have
hinted at this possibility by adding VCFG to the TAFs for BFD,
IPT, UNV and AOO.
Fog should dissipate fairly quickly after sunrise on Wednesday.
However, any low clouds over the Lower Susq Valley may be
slower to budge on Wednesday and MVFR cigs could persist into
the late morning or early afternoon hours.
Outlook...
Thu-Sun...Predominantly VFR. Morning valley fog possible.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Jurewicz/Lambert
NEAR TERM...Lambert
SHORT TERM...Jurewicz/Lambert
LONG TERM...Jurewicz/Tyburski
AVIATION...Evanego/Tyburski

NWS CTP Office Area Forecast Discussion