York, Pennsylvania 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

908
FXUS61 KCTP 121532
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
Issued by National Weather Service Binghamton NY
1132 AM EDT Mon May 12 2025

.SYNOPSIS...
* Dry conditions will continue into this afternoon for much of
  the area before showers spread across the area from southwest
  to northeast.
* Showery weather will occur Tuesday into Wednesday, with
  unsettled conditions expected to persist through the late week
  period and possibly into the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
1030 am update... Late morning satellite imagery shows
generally sunny skies holding on across central PA, with just
some thin, high-level cloudiness traversing the region. Thicker
clouds are on the horizon upstream, though, and we expect these
clouds to overspread the area from southwest-northeast this
afternoon. Upstream shower activity is as close as central WV as
of this writing, and we anticipate that some of these showers
will make it to the Laurel Highlands by late in the day
(generally 4-6 pm).

Highs this afternoon look to be the warmest over northwest PA,
where a combination of downsloping southeast flow and longest
duration of sunshine should push readings into the lower 80s.
Most other areas will range in the 70s.

Previous discussion... The axis of a sharp, negative tilt ridge
in the mid and upper levels will nearly bisect the Commonwealth
from NW to SE late this morning and will limit the northern
progression of cirrus for the first half of the daylight hours
today.

The initially sharp 20+ deg F north/south sfc dewpoint gradient
last evening with upper 20s across the Central and North, and
upper 40s to near 50F in the south, has diminished a bit early
this morning to about 15 deg F now, as TDs rose into the low 30s
in the north.

Upper-level low pressure centered over the northern Gulf states
begins slowly approaching Pennsylvania today, accompanied by
a gradually increasing chance of rain showers from southwest to
northeast late today/early tonight. This will kick off a
stretch of unsettled weather that will last through much of the
remainder of the week.

Abundant sunshine for the northern half of the State, and
sunshine followed by thickening high clouds in the south this
afternoon, will allow temps to climb into the upper 70s to near
80F across the NW Mtns and Lower Susq Valley, while the far NE
counties and Laurel Highlands peak in the low to mid 70s this
afternoon (either as a result of the notably cooler start to the
day in the upper 30s, or earlier timing of the thicker cloud
cover this afternoon).

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY/...
Increasing upper level diffluence and a lengthy cyclonic plume
of deep moisture with tropical origin, accentuated by a path
over the Western Atlantic, will bring rain - moderate to heavy
at times Tuesday/Tuesday night, thanks to the max in low to mid
level theta-e convergence pivoting right over Southern and
Central PA for several hours as Mid and upper low pressure
slowly moves across the Tenn Valley toward the Central
Appalachians.

Limiting factor for more than a few isolated thunderstorms
is the expected cloud cover that should limit instability
across the region.

Anomalously high PWATs will promote a non-zero threat for flash
flooding Tuesday into Tuesday night across southern
Pennsylvania, where 1-2" (locally higher in storms) of rain
could fall through Wed.

WPC has much of the CWA in their MRGL Risk areas while a small
portion of Scent PA lies within the DY2 SLGT Risk area for
excessive rain - Tuesday/Tuesday night.

&&

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
1130 am Monday update... On the large-scale, a blocky upper-
level pattern will become a bit less blocky later this week to
allow more progression of systems across the CONUS. Thus, the
cutoff low expected to plague the Commonwealth during the
middle of the week is expected to have opened up and largely
lifted north of PA by later Thursday. However, on its heels, a
northern stream trough and associated surface frontal complex
will cross the northern Great Lakes and into the Northeast,
retaining our unsettled weather pattern into the weekend.

As for the daily sensible weather, diurnally favored showers and
thunderstorms appear likely both Friday and Saturday. Given the
seasonally vigorous nature of the aforementioned trough, as
well as exact thermodynamic and shear profiles on each of these
days, some strong to locally severe convection appears to be a
plausible scenario.

There remains uncertainty as to how quickly things dry out by
Sunday. At this early juncture, given the still somewhat
energetic upper-level pattern, we`ve retained 30-50% shower
probabilities.

&&

.AVIATION /15Z MONDAY THROUGH FRIDAY/...
VFR conditions will prevail through this afternoon. Increasing
and lowering clouds will stream in this morning and afternoon
ahead of sub-VFR ceilings moving into the Laurel Highlands of PA
and impacting JST/AOO around/after 00Z Tuesday. Have most sites
south of the northern tier of PA experiencing MVFR ceilings
after sunset with probabilities in the 60-90% range in the
Alleghenies. IFR ceilings look to become nearly certain (80-100%
across the Alleghenies and 60-80% east toward the Susquehanna
Valley) between 06-12Z Tuesday.

Have introduced prevailing -SHRA for all sites as rain
approaches from the southwest this evening and tonight. Winds
will veer southeasterly today with speeds topping out between
5-10 knots this afternoon.

Outlook...

Tue-Wed...Restrictions are likely, with lower clouds and
numerous showers.

Thu...Early restrictions in lower clouds, fog, and showers are
possible. Some improvement is possible by afternoon prior to
additional showers and storms developing.

Fri...Showers and afternoon thunderstorms, restrictions
probable.

&&

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

&&

$$

SYNOPSIS...
NEAR TERM...Jurewicz
SHORT TERM...
LONG TERM...Jurewicz
AVIATION...