280
FXUS61 KCTP 150517
AFDCTP

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

.SYNOPSIS...
Lingering showers over the southeast will come to an end after
midnight with the passage of a cold front. This will be
followed by Canadian high pressure building in for this weekend,
bringing lower humidity. After that, the big story will be
building heat as a subtropical ridge builds over the eastern
United States next week.

&&

.NEAR TERM /THROUGH TODAY/...
Any evening showers/storms will  exit the Lower Susq Valley by
early morning, as the cold front pushes east of the
commonwealth. High pressure building in behind the front should
bring clearing skies, cooler air and lower humidity overnight.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
Canadian high pressure building southeastward into PA will
bring fair weather this weekend, with abundant sunshine,
seasonably warm days and comfortable humidity.

Dry air above a weak inversion in the model soundings suggest
dewpoints will fall below NBM guidance, especially Saturday, so
have leaned drier than guidance.

Ideal conditions for radiational cooling appear likely Sat
night under the surface high, resulting in min temps several
degrees below mid June normals. Temps at daybreak on Sunday
will range from the mid 40s across the nrn mtns to the mid 50s
in the Lower Susq Valley. Expect another pleasant afternoon
Sunday with low dewpoints and highs in the upper 70s to mid 80s,
about 5 deg warmer than Saturday. Warm advection will be
underway Sunday night, with low temps in the 50s to low 60s.

&&

.LONG TERM /MONDAY 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 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.

Moisture may be slow to advect into the region initially, with
dewpoints Monday afternoon expected to be in the range of
60-65F. Thus Mon heat index values are forecast in the mid to
upper 90s, with some valley locations across central/southern PA
pushing close to the 100F mark.

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 /05Z 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/Evanego/RXR
NEAR TERM...Evanego/RXR
SHORT TERM...Evanego/Colbert/RXR
LONG TERM...Colbert/NPB
AVIATION...Jurewicz/Evanego/RXR