497
FXUS61 KCTP 151540
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1140 AM EDT Sat Jun 15 2024

.SYNOPSIS...
Canadian high pressure will build southeastward into
Pennsylvania this weekend, providing sunshine, seasonable
temperatures and low humidity this weekend. For next week, an
anomalous subtropical ridge will build over the East Coast
accompanied by an extended period of hot and humid weather.

&&

.NEAR TERM /THROUGH TONIGHT/...
Canadian high pressure building southeastward into PA will
provide fair weather this aftn with a good deal of sunshine,
seasonably warm temps and low humidity. Fair wx cu will
continue to develop overhead, but partly to mostly sunny skies
should prevail this afternoon.

Dry air above a weak inversion in the model soundings suggest
dewpoints will fall below NBM guidance this afternoon, so have
trended lower than the guidance.

Model guidance indicates there will be some cirrus drifting
over PA overnight, in advance of a weak shortwave cresting the
ridge axis over the Grt Lks. However, model RH profiles indicate
it should be relatively thin and not significantly affect
radiational cooling, which otherwise looks favorable under the
surface high. Have, therefore, undercut NBM min temps a bit,
with lows ranging from the low 40s in the coolest northern
valleys to the mid 50s in the urban centers of the Lower Susq
Valley.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
The surface high will pass east of PA Sunday, resulting in a
slightly warmer return southerly flow. After a pleasantly cool
start, it will be a seasonably warm afternoon with all but
perhaps the highest elevations topping 80 degrees.

A building subtropical ridge along the East Coast and the
passage of a warm front on Monday will herald the arrival of
more heat and humidity. There is an outside chc of a
shower/storm over the the higher terrain of the Allegheny
Plateau on Monday. Otherwise, it will be a very warm and
increasingly humid afternoon.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
Little change with the late evening update outside of limiting
chances of diurnal showers/storms on Tuesday. Have kept chances
into the middle/end of the week due to some uncertainty.

Prev..

Confidence is increasing for a heat wave later next week with
the potential for 4-6 consecutive days of MaxT 90F+ across
much/all of central PA. The prolonged nature of this heat wave
may have cumulative adverse effects on vulnerable populations
exposed to heat, with heat related illnesses possible if proper
precautions are not taken. Outdoor workers and individuals with
preexisting health conditions will be among those most at risk.

Tuesday through Thursday (and potentially Friday-Saturday) are
progged to be the warmest days of the week, with most guidance
showing a 595-600 dm 500 hPa ridge centered over the area.
Southerly flow will usher in higher dew points Tuesday that will
allow for heat index values to reach 100-105 degrees over a
large portion of the area. With the large high pressure system
overhead, winds will be light and clouds will be few. Keep in
mind that the sun angle will be at its max next week as we
approach the summer solstice. The intense sun and lack of a
breeze will exacerbate the impacts of heat. Beyond Thursday,
uncertainty begins to develop regarding the shape of the ridge
and the possibility of convection firing along the periphery of
the high pressure system, but the potential for highs in excess
of 90F continues through Saturday.

&&

.AVIATION /16Z SATURDAY THROUGH WEDNESDAY/...
12z update... Any fog patches should burn off quickly by
13z, given a deep layer of dry air aloft and large-scale
sinking motion. There is high confidence of VFR conditions
(80-90%) for the remainder of the valid TAF period (through 12z
Sunday).

One small fly in the ointment could be KBFD later tonight (after
04-06z), as patchy river valley fog over northern PA could
impact this site. Given the very dry air mass, confidence in
this scenario (10-20%) is low enough to keep out of the TAF at
this time. We`ll continue to monitor with later forecasts.

Surface winds should be light (mostly under 5 kt) through
13-15z, then pick up out of the NW to 8-10 kt, before
diminishing again by/after 00z.

Outlook...

Sat-Wed...Predominantly VFR, with building heat next week.

&&

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

&&

$$

SYNOPSIS...Evanego
NEAR TERM...Fitzgerald/Evanego
SHORT TERM...Evanego
LONG TERM...Colbert/NPB
AVIATION...Jurewicz/Evanego/RXR