968
FXUS61 KCTP 241425
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1025 AM 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 /THROUGH TONIGHT/...
Good surge of moisture (PWAT of 1.4-1.7 inches) and forcing is
starting to bring showers into the NW late this AM. There is a
very small chc of thunder with some already occurring just to
the west at 14Z. More showers and likely a few TSRA come into
the SWrn zones in the afternoon and evening. WPC has painted a
MRGL risk of excessive rainfall for portions of Somerset and
Cambria up through Warren County, though antecedent dry
conditions should limit the risk for flooding and rain will be
mostly beneficial. The best chc for heavy rain/TSRA will be
close to sunset over the wrn half.

Highs today will remain several degrees below average thanks to
persistent cloud cover in southeast flow. Highs in the 60s (and
perhaps upper 50s in north central PA) will combine with gusty
southeast winds and occasional showers to make it a raw day.

More dismal drizzly weather is on tap for the overnight. Temps
won`t fall more than 5-7F through the night again.

&&

.SHORT TERM /WEDNESDAY/...
Model guidance outlines another surface low-pressure system
tracking northeastward across the Great Lakes and into southern
Ontario on Wednesday, with slightly more moisture and lift
available as the warm front aligns itself north-to- south across
west-central PA. Given slightly better lift with this low-
pressure system overhead coupled with enhanced moisture, have
retained likely PoPs on Wednesday with highest chances during
the late morning to early afternoon hours. Heavy rainfall
threats look less robust compared to previous forecast cycles;
however, some instability will allow for thunderstorms across
the Laurels, brining some potential for locally heavy rainfall,
with maximum totals ~0.50" on Wed. Storm total rainfall (Tuesday
+ Wednesday) will generally remain below 1 inch, with 0.25" to
0.75" as the most likely range. This rainfall, spread out over
48+ hours, will be helpful for ongoing drought conditions across
southwest PA.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
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 PTC9
approaching the area.

There is still some uncertainty in regards to how PTC9 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 /14Z TUESDAY THROUGH SATURDAY/...
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...Lambert/Dangelo/Banghoff
SHORT TERM...Lambert/Dangelo/Banghoff
LONG TERM...Lambert/NPB
AVIATION...Fitzgerald/Martin