260
FXUS61 KCTP 151016
AFDCTP

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

.SYNOPSIS...
Canadian high pressure will push southeast into Pennsylvania
this weekend, then an anomalous subtropical ridge will build
over the East Coast next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Early morning satellite imagery shows fairly extensive valley
fog across Central PA. Latest SREF/NAMNest and LAMP guidance
indicate the fog will disperse by 12Z-13Z. Canadian high
pressure building southeastward into PA will bring fair weather
to the area today with a good deal of sunshine, seasonably warm
temps and low humidity. Dry air above a weak inversion in the
model soundings suggest dewpoints will fall below NBM guidance
this afternoon, so have leaned toward the drier MAV guidance.

Model guidance indicates there will be some cirrus drifting into
PA tonight 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 and leaned
toward the cooler MAV numbers, with lows ranging from the low
40s in the coolest northern valleys, to the mid 50s in the more
urbanized locations of the Lower Susq Valley.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY/...
The surface high should pass east of PA Sunday, resulting in a
slightly warmer return southerly flow. Model 850mb temps near
14C support highs a few degrees higher than today, with max
temps ranging from the mid 70s over the mountains north of KIPT,
to the low 80s most other locations. A building subtropical
ridge along the east coast and the passage of a warm front early
Monday will herald the arrival of much warmer early next week.
Warm temps aloft should suppress convection and 850mb temps
surging to near 17C supports highs Monday afternoon in the mid
80s to low 90s.

&&

.LONG TERM /MONDAY NIGHT 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 /10Z SATURDAY THROUGH WEDNESDAY/...
06z update... Now that a cold front has pushed to the south and
east of the Commonwealth, skies have cleared out for the most
part. However, satellite imagery and surface observations have
depicted patchy valley fog in the pre-dawn hours, especially
where heavier rainfall occurred Friday afternoon and early
evening. For this reason, we have moderate confidence (40-60%)
in at least MVFR visibility restrictions through about 12z. At
this time, KUNV and KIPT seem to be the most likely sites to see
at least brief IFR restrictions.

Any fog patches should burn off quickly by 12-13z, given a deep
layer of dry air aloft and the expectation of large-scale
sinking motion. There is high confidence of VFR conditions
(90+%) for the remainder of the valid TAF period (through 06z
Sunday).

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