743
FXUS61 KCTP 010317
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1117 PM EDT Sun Jun 30 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 MONDAY 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 fairly widespread high end MVFR and low end VFR ovc
cigs across the NW 1/3 of the state attm and this cloud deck
will continue to advance just a bit more 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 some brief very light showers
from the 2-3 kft thick strato cu layer across the Northern Mtns
overnight, 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 MONDAY MORNING THROUGH 6 PM MONDAY/...
High pressure builds in over the next 30 hrs. Mon should be
sunny after the clouds in the NW 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.

Monday night 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.

&&

.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
Canadian high pressure builds to southern Ontario by Monday
night, bringing a fair and cool night with the high moving
directly overhead. This will result in efficient radiational
cooling and min temps several degrees below normal. 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.

All medium range guidance tracks a weakening shortwave well
north of PA late Wednesday 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 week, due to more clouds/showers. However, high pwats
in the vicinity of the stalling front should result in muggy
nights and above normal min temps the entire second half of next
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 /03Z 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. 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.
Bufkit soundings support 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...DeVoir/Bauco
AVIATION...Fitzgerald
CLIMATE...Evans/Steinbugl