352
FXUS61 KCTP 111109
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
709 AM EDT Mon Aug 11 2025

.SYNOPSIS...
* Early this week will feature a continuation of mainly clear
  skies with slowly warming daytime and overnight temperatures.
* We`ll see and uptick in humidity for the early to midweek
  period with scattered showers and thunderstorms returning to
  the region late Tuesday across the west and elsewhere on
  Wednesday as a weak cold pushes Southeast from the Great
  Lakes.
* A return to dry and warm conditions will comfortably lower
  humidity for Thursday and Friday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Surface high pressure (1025 mb) was centered just off the NJ
coast early today while the sharp ridge of high pressure aloft
stretched from the Delmarva Coast to Northern Maine.

The area of anomalously low PWAT air (0.6 to 0.8 of an inch)
situated beneath this mean mid-upper level ridge and covering
much of the CWA early this morning, will lift NE to the Catskill
and Leatherstocking regions of Upstate NY by early this
evening.

PWAT values will increase by 0.4 to 0.5 (to 1-1.25 inches) by
22Z today and remain at that level overnight.

This will mark the end to our stretch of days with comfortably
low RH and corresponding cool nights as sfc dewpoints climb into
the 60s.

Abundant sunshine will prevail today with MU CAPE peaking below
750 J/KG across the eastern half of PA - close to the
aforementioned sfc and upper level ridges. In contrast, MU CAPE
will climb to around 1500-1700 J/KG later this afternoon across
the Western third of PA. Forecast soundings suggest there could
be some stray, slow moving/pulse SHRA/TSRA in the 17Z Monday to
01Z Tuesday period, mainly near and to the west of the RT 219
corridor across our Western zones. Will coordinate with
surrounding WFOs PBZ CLE and BUF a small 10-15% increase in
POPS for this afternoon and early evening across our NW Mtns and
Laurel Highlands.

High temps this Monday will be 1-2 deg F higher than Sunday, or
generally in the mid to upper 80s. A few of the bigger cities
across the Lower Susq Valley could peak around 90F this
afternoon.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
Tonight and Tuesday will bring an increase in humidity with sfc
dewpoints gradually rising to the mid 60s (Northern and Western
Mtns) to low 70s Central and Southern Valleys) on Tuesday.

Low level forcing will be weak and mainly due to topography. In
addition, mid level temps will warm slightly to between 8-9 deg
C at 700 mb. Still, MU CAPE values increasing to between
1300-1700 J/KG will bring isolated to sctd afternoon showers and
TSRA into the picture for Tuesday afternoon and evening.

Low temps tonight will range through the 60s with highs on
Tuesday ranging from the mid to upper 80s across the Northern
and Western Mtns to the low 90s across the Susq Valley and
adjacent Scent PA valleys.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Ridge axis overhead will continue to get pinched thinner early
in the week, and eventually merge with/migrate into the mid-
latitude Atlantic ridge. The sfc low will also slide eastward.
That will set up a good srly/moist flow. Expect the humidity to
get muggy with heat index values getting into the upper 90s
for the mid-week period.

A sfc cold front pressing down from the N/NW will probably
stall out just about over PA and cause the chc of SHRA/TSRA to
increase with a peak of afternoon/diurnal convection each day.
The peak PoPs are placed on Wed, but Thurs into next weekend
hold a good (30-40%) chc of getting wet, more so over the srn
counties than nrn locales.

&&

.AVIATION /11Z MONDAY THROUGH FRIDAY/...
Patchy low clouds (cigs ~1 kft) drifted northward into the
Lower Susq Valley around sunrise this AM. Elsewhere, skies
remain clear.

Any lingering low clouds should quickly dissipate this morning,
leaving fair skies and widespread VFR conds beneath a bit of
high cloudiness for this afternoon. Predominantly light and
variable winds will become southerly around 5 kts.

Models suggest a better chance (~60% prob) of low clouds
building northward into at least the Lower Susq Valley tonight.
This is represented in the 12z MDT and LNS TAFs.

Outlook...

Tue...AM low clouds across Lower Susq Valley; Otherwise,
generally VFR with spotty SHRA/TSRA possible in the aftn/eve.

Wed...More numerous SHRA/TSRA expected.

Thu-Fri...Chance of a shower or storm, mainly across the south
during the aftn/eve hours.

&&

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

&&

$$

SYNOPSIS...Lambert
NEAR TERM...Lambert
SHORT TERM...Lambert
LONG TERM...Lambert/Dangelo
AVIATION...Evanego