416
FXUS61 KCTP 010701
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
301 AM EDT Mon Jul 1 2024

.SYNOPSIS...
A large high pressure system will build into the region tonight
and Monday, followed by a dying cold front pushing in from the
Great Lakes and stalling out over the area by the middle of next
week.

&&

.NEAR TERM /UNTIL 8 AM THIS MORNING/...
Much drier air advecting into the region this evening with
mainly clear skies noted over the Bulk of Scent PA and the Susq
Valley at 0130Z.

Cooler air and steep llvl lapse rates advecting SE beneath a
moderately strong subsidence inversion based at 4-5 kft agl was
producing a very rare case of lake effect clouds over and SE of
Lake Erie (850 mb temps around +2-3C at KBFD) with fairly
widespread high end MVFR and low end VFR OVC cigs across about
the NW 1/2 of the state attm and this cloud deck will continue
to advance just a bit more south and east overnight, but greatly
break up to sct- bkn VFR (>3000 FT agl) across the Central
Ridge and Valley region.

Aside from some patchy drizzle or a few periods of very light
rain from the 2-3 kft thick strato cu layer across the Northern
Mtns overnight (with QPF generally a few hundredths of and inch
or less), POPs over the Central Ridge and Valley Region and SE
PA (where skies will be mainly clear) will be essentially zero.

Low temps will vary from the upper 40s throughout the perennial
cold rural valleys of the NW Mtns and Somerset Cty, to around 60
in the SE Metro Areas.

&&

.SHORT TERM /8 AM THIS MORNING THROUGH 6 PM TUESDAY/...
High pressure (1026 mb or +2 Sigma) builds in over the next 30
hrs and becomes centered near the PA/NY border late tonight.

Today should be sunny after the clouds over the Northern and
Western Mtns dissipate (for the most part). Wind continues to
veer to the N and the dewpoints should drop even more in the
deepest mixing of the day. Td in the m40s should be common in
the wrn half of the CWA in the aftn.

Tonight should be foggy in the nrn and central valleys despite
the dewpoints in the 40s as the air temp should get a bit lower
than the river/creek water temps. Otherwise, light/no wind under
the center of the 1025 high pressure area will help temps down
into the m40s to l50s.

Fair and warmer weather is expected Tuesday into at least the
first half of Wednesday, as upper level ridging builds over the
state and surface high drifts offshore.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Central US upper ridge will drift east and maintain fairly good
amplification until Wednesday night/Thursday when a weakening
shortwave passes well north of PA late Wed into Thursday.

The dying cold front is likely to sag into the state Thursday
and stall out in the vicinity of PA through Friday.

Falling heights/surging low level moisture ahead of the front
could support scattered convection as early as Wednesday
afternoon over the northwest half of PA. However, a better
chance of showers/tsra areawide will come with the arrival of
the front Thu into Friday. Early best guess of late week
rainfall based on ensemble plumes ranges from 0.25 to 0.75
inches, with the highest amounts over the N Mtns and least in
the south.

Heat and humidity should peak ahead of the front Wed-Thu.
Ensemble mean 850mb temps surging to near 20C indicate max temps
could reach the low to perhaps mid 90s in the Lower Susq Valley
Thursday, with high humidity pushing heat indices into the mid
and upper 90s.

Ensemble plumes suggest slightly cooler daytime temps late in
the week, due to more clouds and scattered mainly afternoon and
early evening showers and TSRA. However, high pwats in the
vicinity of the stalling front should result in warm and humid
days followed by muggy nights and above normal min temps the
entire second half of this week.

Models begin to diverge as we head into the weekend. Most
guidance suggests that rain chances stick around through at
least Saturday as another cold front approaches the area.

&&

.AVIATION /07Z MONDAY THROUGH FRIDAY/...
High pressure building in from the Grt Lks will bring VFR and
breezy conditions to most of Central PA tonight. However,
residual low level moisture ascending the Alleghenies will
result in predominantly MVFR cigs from KBFD southward through
KJST, with tempo IFR cigs in vicinity of KBFD through around
06Z. MVFR is also possible at AOO and UNV. A downsloping flow
should keep conditions VFR east of the Alleghenies tonight.

Mixing of much drier air aloft should cause any early stratocu
to dissipate by late Monday morning, with widespread VFR
conditions expected the rest of the day. A fairly tight pressure
gradient should result in gusty north winds for much of the day
with gusts in the 20-25kt range for most of the region. Expect
winds to diminish toward evening, as the center of the high
pressure system pushes into PA.

Outlook...

Tue...Patchy AM valley fog N Mtns.

Wed...Evening tsra impacts possible NW Mtns.

Thu...AM low cigs possible W Mtns. Sct PM tsra impacts
possible.

Fri...Sct tsra impacts possible, mainly PM.

&&

.CLIMATE...
At the Altoona Airport, a daily record rainfall of 0.77 inches
was set on Sat, Jun 29. This total breaks the old record of
0.53 inches set back in 1972.

&&

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

&&

$$

SYNOPSIS...Lambert/DeVoir
NEAR TERM...Lambert/Dangelo
SHORT TERM...Dangelo
LONG TERM...Lambert/Bauco
AVIATION...Fitzgerald/Colbert
CLIMATE...Evans/Steinbugl