Raven Run, Pennsylvania Weather Forecast Discussion

604
FXUS61 KCTP 210933
AFDCTP
Area Forecast Discussion
National Weather Service State College PA
533 AM EDT Sun Sep 21 2025
.SYNOPSIS...
* Above average temperatures to close out astronomical summer
  2025
* Rain chances will increase across the region Monday and
  Tuesday
* At this early vantage point, there is uncertainty as to
  whether showery, unsettled conditions last into next weekend,
  or improvement takes place by then
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Recent high resolution model guidance over the past few days
accurately depicted the formation/advection and extent of a
large area of stratus/stratocu across the Commonwealth early
this morning under an extended period of low level serly flow.
We`re seeing a transition to a definitive, deepening south to
swrly flow that will feature several opportunities for showers
and perhaps a few rumbles of thunder with the passage of a few
weak boundaries. More on that below.
For today, SE to southerly flow respectively, in the sfc-4 kft
agl layer should help to greatly delay or prevent the break up
of the stratus/stratocu decks, leading to noticeably cooler late
morning/afternoon temps than Saturday.
Max temps this afternoon will range from the upper 60s across
the highest terrain (including the NW Mtns and Laurel
Highlands and the north-central mtns.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
The greatest chances for rain/showers during the period will be
late tonight into early Monday and again late Monday 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
DY2 SPC MRGL threat for SVR TSRA.
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.
Lows tonight will be mainly in the mid to upper 50s with the
Western Poconos seeing some readings right around 50 deg F.
High temps Monday 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 /MONDAY NIGHT THROUGH SATURDAY/...
Strong sfc high shifts to the Northeastern Seaboard early next
week. This will allow a +tilt upper level trough and llvl
frontal boundary to move southeast from the Great Lakes bringing
the best odds for rain particularly on Tuesday focused across
the northwest 1/2 of central PA.
Confidence is increasing for a more southern track to the slow
moving cutoff low late next week and weekend, with an increasing
probability of dry/pleasant cool conditions Friday through
Sunday. The ICON and EC and its ensembles have been the most
consistent with their handling of this system and keeping it`s
impacts minimal if any here in Central PA.
GFS`s jet core is across James Bay Canada for the Fri-Sun
9/26-9/28 period, but the northern stream flow veers and becomes
more nwrly with the passage of a significant and fast moving
short wave in that northern branch of the jet. 00Z EC is much
more northwesterly and 300-400 NM further to the south with its
main upper level jet, which places much of PA in the sweet spot
for confluent flow aloft and deep dry air with low daytime
humidity.
Latest...06Z Sat run of the NBM v4.3 6 via WSUP viewer shows
6-hourly POPS AOA 15 percent for much of the CWA SAT 9/27, after
some potentially minor WAA ahead of the upper trough at POPS of
20-25 percent Friday 9/26.
&&
.AVIATION /09Z SUNDAY THROUGH THURSDAY/...
00z update... Confidence is increasing (80-90% probability) in
the development of IFR to fuel alternate ceiling restrictions
later tonight and Sunday morning across the central PA terminal
sites. IFR ceiling bases are most probable at KBFD, KJST, and
KAOO.
It`s also appearing more likely that drier air slowly filters
into the region from the east during Sunday afternoon. At this
early vantage point, we think improving conditions will take
place first at KLNS, KMDT, and KIPT, eventually reaching KAOO,
KUNV, KJST, and KBFD by/after 18-19z.
E-SE surface winds of 5-10 kt are expected through the day on
Sunday.
Outlook...
Mon-Thu...SHRA and PM TSRA 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
NEAR TERM...Lambert/Bowen
SHORT TERM...Lambert/Bowen
LONG TERM...Lambert/Steinbugl
AVIATION...Jurewicz/NPB
CLIMATE...Steinbugl

NWS CTP Office Area Forecast Discussion