024
FXUS61 KCTP 172011
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
411 PM EDT Thu Jul 17 2025

.SYNOPSIS...
* Dry and Breezy for the bulk of Central PA for the rest of
  today and tonight as a cold front pushes through.
* Isolated to scattered thunderstorms will form this afternoon
  and early this evening, mainly across the southern tier
  counties and far Eastern PA; with a drier trend still
  anticipated for Friday into Saturday
* Heat risk peaks today; then a modest cool down with lower
  humidity levels as the week draws to a close

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Mid/Upper level short wave will be moving east across Lake
Ontario this afternoon with ~1000 mb surface low moving across
the CYOW. Southward trailing cfront will cross the CWA late this
afternoon...and early this evening over the Lower Susq Valley.

Very warm mid level temperatures of +10.5C to +11C coupled with
the unfavorable, right exit region of the mid and upper level
jet pushing across Central PA will lead to deep, broadscale
subsidence and dry/breezy conditions across much of the CWA
through tonight.

However, as the aforementioned front encounters the hot, humid,
and unstable air mass out ahead of it, we do anticipate that at
least a few hit and miss thunderstorms will develop, mainly
across the SE quarter of the CWA.

As far as storm intensity is concerned, there are factors at
play which could favor localized strong/damaging gusts across
our SE zones into this evening, with drying aloft helping to
enhance DCAPE values, as well as better environmental wind flow
as compared to recent days, featuring 35-40 kt flow in the mid-
levels. The excessive rainfall threat seems much reduced today,
with a lower precipitable water environment, along with brisk
cell motions to limit residence time in any one spot.

Lastly, since our southern areas, namely the Cumberland and
Lower Susquehanna Valleys, will stay in a pre-frontal
environment the longest, it will become hot and humid this
afternoon. Since apparent temperatures will approach and locally
exceed 100f, a Heat Advisory remains in effect until 8 pm this
evening.

Later tonight, any residual showers and thunderstorms should
quickly fade across the SE.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
As the jet max proceeds east and the right entrance region (and
associated upward motion) drags across southern PA early Friday,
we expect the western part of the cold front to slow then stall
out overnight across the Upper Ohio River Valley and Laurel
Highlands, allowing a weak wave of surface low pressure to ride
east along it and return layered clouds and a few periods of
showers across mainly southwest and South-central PA on Friday.

The rest of Central and Northern PA will see variable amounts of
clouds and sunshine for Friday, along with dry conditions and
notably lower humidity. Friday will feature just a light
northerly breeze.

Dry conditions should persist Friday night into Saturday
morning, although clouds may be on the increase from southwest-
northeast, especially across the Alleghenies, as moist and warm
advection aloft already gets underway.

A returning surface warm front is expected to bring a renewed
threat of showers and thunderstorms Saturday afternoon and
Saturday night, particularly for areas west of about US-15 and
north of about I-80.

Although the air mass turns more muggy again Saturday, a good
deal of cloud cover should cap afternoon highs in the low-mid
80s range.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
Once again, no significant pattern changes are on the horizon.
We`ll continue to see an elongated summertime upper ridge axis
from the southwestern Atlantic across roughly the southern half
of the CONUS, with an energetic northern stream near the
international border with Canada.

As for the daily sensible weather, recent medium-range model
guidance suggests that a shortwave trough within the above
mentioned belt of westerlies will amplify enough later this
weekend and early next week to help drive a surface cool front
down into the southern Mid-Atlantic. This would allow another
refreshing air mass to at least briefly build over the
Commonwealth later Sunday and Monday. Prior to that, though, the
passage of the cool front itself on Sunday should spark some
showers and thunderstorms.

Towards the middle of next week, longer range guidance is still
suggestive of the southern CONUS upper ridge flexing its muscle,
with accompanying height rises for PA signaling a gradual return
of heat and humidity, along with increased chances for
afternoon/evening focused showers and thunderstorms.

&&

.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
For the rest of this afternoon and early evening, the influx of
a drier and better/deeply mixed environment will lead to
primarily VFR area-wide. Hit and miss thunderstorms are expected
to form along an approaching cool front, but any restrictions
look brief. KMDT, and KLNS stand the best shot at having
thunderstorms at least in the vicinity.

Tonight, some post-frontal/upslope lower clouds could bring
IFR-fuel alternate restrictions for a time at KBFD and KJST.
Elsewhere, VFR should prevail for the central PA terminal sites.

Look for West-Southwest to Westerly wind at 12-15 kt, with
gusts into the 20 to low 30s common this afternoon. NW winds
should diminish tonight to 5-8 kt. Light north wind expected for
Friday.

A weak wave of low pressure moving east our of the Ohio Valley
along a stalling front across SW PA will lead to borderline
IFR/MVFR CIGS for much of Friday across our SW zones and KJST,
while any early to mid morning post frontal MVFR strato cu will
dissipate by around 15Z Friday.

Outlook...

Fri-Sat...Mainly dry through Saturday morning, with increasing
chances for afternoon/evening showers and thunderstorms.

Sun...Numerous showers and thunderstorms anticipated.

Mon...Dry conditions seem likely.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 8 PM EDT this evening for PAZ036-056-057-
059-063>066.

&&

$$

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