149
FXUS61 KCTP 021751
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
151 PM EDT Tue Jul 2 2024

.SYNOPSIS...
A large high pressure system will build into the region tonight
and Tuesday, followed by a dying cold front pushing in from the
Great Lakes and stalling out over the area by the middle of
next week. Very warm and quite humid air will return for the
second half of this week and last into the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
A crisp, fall-like morning is underway across the Commonwealth
with temperatures in the mid 40s to near 60 from northwest to
southeast. Nighttime Microphysics satellite imagery shows fog in
the deepest valleys in northern PA (mainly north of I-80). Fog
will mix out by 8 or 9am as temperatures quickly rebound under
abundant sunshine.

A surface high will remain parked over the state today, so
expect humidity to remain low with yet another gorgeous day in
store. Mixing down model 850mb temps of around 13C translates
to expected highs ranging from the mid and upper 70s over the
higher terrain of the Alleghenies, to 80-85F in the valleys.
These temperatures are right around average for this time of
year. Very dry air above a weak inversion the forecast
soundings is a reliable indicator of dewpoints falling below NBM
guidance, so have leaned toward the lower MAV/NBM10pct numbers.
Warm advection aloft ahead of a weak shortwave cresting the top
of the ridge will likely produce some thin cirrus today, but
sunny to mostly sunny wording should suffice.

Another pleasant night is in store with light winds, low
dewpoints, and dry conditions. Some mid and high level clouds
will limit radiational cooling just enough to preclude much fog
development by Wednesday morning. Lows will generally be around
60F. Enjoy the cool temperatures, because warmer and more humid
air will begin to build in by Thursday.

&&

.SHORT TERM /WEDNESDAY/...
A warming trend will continue into Wednesday with an uptick in
humidity as the surface high drifts off of the Mid Atlantic
coast, accompanied by a return southern flow. GEFS 2m temp
anomalies are a few degrees above normal over the W Mtns and
near average elsewhere, translating to highs well into the 80s.
Moisture advection ahead of an upstream cold front could
potentially support a shower/tsra toward evening across
Warren/Mckean counties. Otherwise, upper level ridging should
ensure another mostly sunny, rain-free day across Central PA.

As troughing begins to approach the region Wednesday evening, a
shower or thunderstorm is possible in northwest PA. SPC and WPC
have both placed northwest PA in a Marginal Risk for severe
wx/flooding respectively Wednesday evening.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
All medium range guidance tracks a dying cold front southward
into Central PA Thursday, accompanied by a good chance of
showers/tsra. Latest RH profiles suggest there will be plenty of
cloud cover and progged mid level flow doesn`t look overly
impressive. Therefore, the severe weather threat currently looks
limited. Best guess of areal average rainfall looks to be
between 0.25 and 0.50 inches based on ensemble plumes.

The front is progged to stall out in the vicinity of Southern
PA Thursday night, then return north as a warm front Friday
ahead of low pressure lifting across the Grt Lks. Falling
heights and surging pwats ahead of an upstream shortwave and
associated surface low lifting across the Grt Lks should bring a
round of showers/tsra in the Friday PM to Saturday timeframe.
Current guidance suggests the shortwave and bulk of the large
scale forcing will pass north of PA, leading to unimpressive
mean qpf in the ensemble plumes of 0.25 to 0.50 inches Fri PM to
Saturday.

The bulk of guidance now supports fair and seasonable conditions
Sunday into at least early Monday, as surface ridging and drier
air work in behind the cold front. Showers and storms return to
the forecast for early next week as another wave of low
pressure tracking to our north brings a cold front through the
region.

Temperatures in the long term forecast look above average,
especially overnight lows Thursday and Friday night, when EPS
pwats are 150pct of normal.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
VFR conditions and mainly clear skies will prevail through early
this morning. There is a very small chance (<20%) that patchy
valley fog will impact airfields in the NW mountains. VFR conds
will continue into the day with high cirrus areawide and a few
fair weather cu across the south.

Outlook...

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.

Sat...Chc tsra throughout the day.

&&

.CLIMATE...
June 2024 was the warmest June on record for Bradford with a
mean temperature of 66.6F, breaking the old record of 65.8F set
in 2021.

June 2024 was the 3rd warmest June on record for Harrisburg with
a mean temperature of 76.0F.

&&

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

&&

$$

SYNOPSIS...Lambert
NEAR TERM...Banghoff
SHORT TERM...Fitzgerald/Banghoff
LONG TERM...Fitzgerald/Bauco
AVIATION...Colbert/Bowen
CLIMATE...Colbert