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252
FXUS61 KCTP 242241
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
641 PM EDT Tue Sep 24 2024

.SYNOPSIS...
An amplifying upper level trough and slow moving frontal
system will bring showery conditions to Central Pennsylvania
through at least Wednesday, along with a few rumbles of thunder.
As such, it will be cloudy and cool through midweek. The latter
part of the week looks milder with at least partial sunshine
expected into the weekend.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
-- Changed Discussion --
Stable air along and east of the mountains quashed earlier line
of storms traveling into the MD panhandle. It`s a murky evening
with light to moderate shra throughout central PA as first in a
series of shortwaves riding through the channeled southwest flow
passes overhead, reaching the Pocono Plateau by 03z. Behind this
feature, it will remain overcast and drizzly with pockets of
light rain. However, more organized precip/showers move back
into the srn counties after 06Z and slide over the Lower Susq,
mainly S of the Turnpike, as deep layer moisture increases and
additional large scale lift arrives. Temps won`t move much
(down maybe only 5-8F thru the entire night, again) and need
little editing in the grids.
-- End Changed Discussion --

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
Upper ridging continues to pump up, more so to our east then
overhead. The low pressure center associated with all this
light rain will slide generally northward. This will mean a
prolonged time of similar conditions. The moisture feed/PWAT
gets a bit less favorable over the west, but stays in the 1.75"
range in the SErn counties. Basin average QPF is less than half
of an inch over all of the area, and many places will have less
than a quarter of an inch across the short term period (Wed-Wed
night). Again, little change to temps across the 24 hours. Will
stick with continuity on temps. Sky cover pretty solid for most
of the time on the deep SE flow.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Lingering showers across mainly E PA will continue into
Thursday before a brief reprieve in rainfall. Shower chances
will increase Thursday afternoon into the morning hours of
Friday with the surface cold front lingering across southern
Pennsylvania. The highest chances will mainly be confined south
of the Turnpike; however, can`t rule out showers making it as
far north as the northern tier Friday evening into Saturday
morning with Chc PoPs across the Laurels throughout the day on
Friday and into Saturday morning.

There is still some uncertainty in regards to how Helene will
impact central Pennsylvania, mainly dependent on interactions
with an upper-level low stationed across the eastern Tennessee
Valley. Deterministic model guidance has outlined that the bulk
of rainfall will stay west of the area while a rather
narrow, negatively tilted upper-level ridge holds strong from
the Great Lakes through the Upper Ohio River Valley. Given the
uncertainty with regards to upper-low interactions, did not
deviate much from continuity and NBM guidance this cycle.

The upper-level low and remnants of the tropical system will
likely drift east across the Commonwealth early next week,
bringing increased chances of shower activity into the beginning
of next week, with highest chances generally across the western
highlands.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
The combination of a moist southeast flow off of the Atlantic
Ocean and a stalled warm front near the PA/OH border will
result in persistent stratus and occasional rain/drizzle across
Central PA through Wednesday.

Upsloping flow should yield the lowest cigs along the spine of
the Appalachians tonight, where LIFR/IFR cigs are very likely
based on current conditions and model output. Further east, MVFR
cigs are currently noted across the Susq Valley, but latest
model soundings and SREF prob charts indicate IFR cigs will
become likely by late tonight. A core of stronger winds aloft
could result in marginal LLWS criteria this evening over the NW
Mtns (KBFD).

Very little change is expected Wednesday, with widespread IFR
cigs and occasional rain/drizzle expected. However, there is
some chance (<50pct) of late day improvement along the spine of
the Alleghenies (KBFD and KJST), as the warm front nudges
eastward.

Outlook...

Thu...AM low cigs/showers likely.

Fri...Patchy AM valley fog possible N Mtns. Slight chance of
showers/low cigs Laurel Highlands.

Sat-Sun...Chance of low cigs/showers, mainly Central Mtns.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

SYNOPSIS...Lambert/DeVoir/Dangelo
NEAR TERM...DeVoir/Dangelo
SHORT TERM...Dangelo
LONG TERM...NPB
AVIATION...Fitzgerald