857
FXUS61 KCTP 182336
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
736 PM EDT Fri Jul 18 2025

.SYNOPSIS...
* A cool night for mid July in store for PA.
* More numerous showers/storms possible late Sat through late
  Sunday as a warm front moves northeast across the region.
* A cold front pushes southeast across PA late Sun/Sun night,
  followed by 2-3 days of dry weather with comfortable, lower
  humidity.
* Another hot and humid spell expected by late next week.

&&

.NEAR TERM /THROUGH SATURDAY/...
A few showers over southern PA early this evening will quickly
lead to clearing skies overnight. Dewpoints below the 50 degree
mark over northern PA now, so looking at a rather cool night for
what is normally the hottest week of the summer.

Earlier discussion below.

The front lingers just South of the border tonight, but drifts
slowly northward late tonight and pushes through much of the CWA
later Sat afternoon and evening.

The main chance for heavier showers and storms will be the far
west and south on Saturday, and the return of warm and humid
air may hint that the southeast part of the CWA has some heavier
downpours late in the day. Thus 2 areas to watch.

Warm advection aloft should keep much of the area capped off,
preventing most deep convection until later Sat. The srn tier
will have the highest PoPs Sat.

High temps Saturday will feature a fairly tight range from the
upper 70s to mid 80s, based greatly on the amount of cloud
cover.

&&

.SHORT TERM /SATURDAY NIGHT/...
No real change to this section of the AFD at this point.

Earlier discussion below.

Saturday night will be warm and muggy in the warm sector as the
warm front moves into Eastern PA/Southern NY. PWAT values will
climb back up to between 1.5 and 1.8 inches across the bulk of
the area.

Min temps Saturday night will range from the mid to upper 60s in
most places to the low 70s in the larger metro areas throughout
the Lower Susq Valley.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Sunday will feature more of a chance of a gusty storm and or
a heavy downpour. Outlooks for now are mainly marginal for our
area. See the HWO for more information.

After the cold front moves across on Sunday, looking at a rather
strong shot of cooler air for mid July to work in for Monday
into Tuesday. Much lower dewpoints and lots of sun, with a
breeze.

Unlike the past few weeks, the pattern now supports more of a
progressive movement of weather systems.

Earlier discussion below.

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 /00Z SATURDAY THROUGH WEDNESDAY/...
A wave of low pressure will move along a stalled frontal
boundary south of the Maryland border this afternoon and evening
and will bring a few hour period of showers to Laurel Highlands
and Scent Counties of the state. JST and AOO will have the best
chance of seeing rain with less than a 10 percent chance of
measurable precipitation NE of a KBFD to KMUI line.

KJST will will quickly see a dip into MVFR conditions before
midnight tonight as a low stratus deck builds in behind the
departing rain showers from this afternoon. KAOO will be
similar to KJST. Both locations will dip into at least the IFR
range late tonight (though CIGS at KJST should drop below 005
for a 6-8 hour period Saturday morning.

The MVFR cloud deck across the SW will likely spread over the
Susq Valley this evening through the overnight.

Elsewhere across Central and Northern PA (KUNV, KIPT and KBFD),
VFR will prevail through much of tonight, but some patchy
ground fog could reduce the VSBY to 1-2 miles late tonight
(06-11Z Sat).

A few showers will continue across the southern half of
Pennsylvania tonight as the stalled boundary begins to lift
northward as a warm front. Model RH profiles suggest that low
clouds and fog will form after ~03Z, with sites west/south of
UNV being most likely to see visibility restrictions develop.

Outlook...

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

Sun...Numerous showers and thunderstorms anticipated.

Mon-Tue...Dry conditions.

Wed...Still mainly dry.

&&

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

&&

$$

SYNOPSIS...Lambert/Dangelo/Martin
NEAR TERM...Lambert/Martin
SHORT TERM...Lambert/Dangelo/Martin
LONG TERM...Jurewicz/Martin
AVIATION...Lambert/Bowen