087
FXUS61 KCTP 241912
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
312 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/...
Storms headed for SW at 19Z are organized into a little bow
echo. They are approaching our fairly stable CWA. This usually
helps keep the strong winds from mixing down. But, we`ll monitor
closely mas SPC MRGL risk gets right up to Somerset Co. CAMs
keep this bath of TSRA as the best/heaviest precip for the
evening. The forcing passes through and into the central mtns,
and deeper into the stable air overhead. Much of the overnight
will be just cloudy and drizzly. However, more organized
precip/showers move into the srn counties after 06Z and slide
over the Lower Susq, mainly S of the Turnpike.

Temps won`t move much (down maybe only 5-8F thru the entire
night, again) and need little editing in the grids.

&&

.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 Thursday evening
and into Friday morning. Rainfall chances begin to increase as
Friday morning progresses with the potential remnants of Helene
approaching the area.

There is still some uncertainty in regards to how Helene will
impact central Pennsylvania, mainly dependent on interactions
with a trough stationed across the eastern Tennessee Valley. At
this time, deterministic and EFS model guidance shows modest
agreement in the bulk of rainfall keeping south/west of the area
while a rather narrow, neg tilt upper ridge holds strong from
the Great Lakes through the Upper Ohio River Valley and Carolina
Coast. Given the still existing uncertainty, did not deviate
much from continuity and NBM guidance once again this model
cycle.

If precipitation manages to make way into central Pennsylvania
in the Friday- Sunday timeframe, highest chances (25-35%) will
be across S/W PA along the Laurels with a SChc (15-25%) progged
west of the Susquehanna Valley. It looks like enough low-mid
level ridging will maintain a deep layer of dry air across the
NE 1/3 to 1/2 of PA to keep precip chcs minimal there through
the weekend.

Upper low and remnants of the tropical system will likely drift
east across the Commonwealth early next week with a fairly good
chc for showers.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
For the late evening update and the 06Z TAF package, I added
a bit more detail.

Overall looking at low CIGS today into tonight, given a
southeast flow of cool, moist air. CIGS may be a bit higher
at MDT and LNS at times, but expect a lot of variation.

Any improvement with CIGS today, will be short lived, as
day light is shorter now, thus expect CIGS to come back down
toward sunset.

Visibilities not bad as of Midnight. The visibility may drop
some when showers become more widespread today, but dewpoints
not fcst to come up much, so time of day may offset the effects
rain become more widespread.

Outlook...

Wed...Low cigs/showers likely. Improving conditions possible
W Mtns Wed PM.

Thu...AM low cigs/showers likely.

Fri...No sig wx expected.

Sat...Chance of low cigs/rain Laurel Highlands.

&&

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

&&

$$

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