083
FXUS61 KCTP 160848
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
448 AM EDT Sun Jun 16 2024

.SYNOPSIS...
High pressure over upstate New York will pass off of the New
England coast today, then an anomalous subtropical ridge will
build over the East Coast next week. The ridge is likely to
weaken and shift south by next weekend, allowing a weak cold
front to approach Pennsylvania from the north.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Mostly clear skies, a calm wind and dry air is resulting in
favorable conditions for radiational cooling and allowing temps
to fall below NBM guidance. Expect readings at dawn to range
from the low 40s in the coolest northern valleys, to the upper
50s in the more urbanized spots of the Lower Susq Valley. Large
air/water temp differences of >25 degrees will result in patchy
early morning valley fog in the deep river/stream valleys of
the Alleghenies, mainly north of I-80.

The surface high over upstate NY will pass off of the New
England coast today, resulting in fair and seasonable conditions
across Central PA with a slightly warmer return southerly flow.
Upstream satellite imagery and model guidance indicate warm
advection aloft ahead of a shortwave lifting over the Grt Lks
will result in some mid and high level cloudiness across Central
PA today, mainly through early afternoon. However, on balance
mostly sunny wording should suffice for the area. Mixing down
model 850mb temps of around 14C yields expected highs ranging
from the mid 70s over the mountains north of KIPT, to the mid
80s in the Lower Susq Valley.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
A building subtropical ridge over the East Coast will bring fair
and increasingly hot weather to Central PA early next week.
Warm mid level temps should largely suppress convection.
However, isolated convection is possible Monday afternoon,
primarily over the Laurel Highlands, where the elevated heat
source could aid in breaking the cap. Isolated pulse-type
convection appears possible Tuesday afternoon, primarily along
the spine of the Alleghenies.

Mixing down 850mb temps yields highs in the upper 80s to low 90s
Monday and mostly low to mid 90s Tuesday. The increasing heat,
coupled with dewpoints in the 65-70F range, could result in
heat index values close to 100F in the lower elevations east of
the Allegheny Plateau by Tuesday afternoon.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
All medium range guidance is in agreement that a prolonged heat
wave will occur throughout the extended forecast period. A
595-600 dm 500 mb ridge will be situated over Central
Pennsylvania and temperatures will easily reach the 90s across
most of the region each day. Heat indices will be in the upper
90s and low 100s, with the Wednesday-Friday timeframe looking
like the hottest period. Some models indicate the potential for
a few showers or thunderstorms each afternoon across the
northern tier, but coverage should be very limited.

Ensembles show the ridge beginning to flatten out a little by
Saturday which would allow for a slightly higher chance of
showers or storms, particularly across the northern half of the
area.

&&

.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
High pressure over the area will keep clear skies and light
winds over our area into Monday morning. The airmass is quite
dry, so the chance of fog is very low, especially with the
short nights.

The earlier shift added VCFG to KBFD and KIPT as overnight low
temperatures near dewpoints that occurred on Saturday.

Outlook...

Mon-Thu...Predominantly VFR, with building heat. Density
altitude concerns possible.

&&

.CLIMATE...
A period of much warmer than average temperatures is expected
across much of central Pennsylvania next week, with record high
temperatures being challenged. The record high temperatures for
some sites across central PA are outlined below:

 Jun 18 Jun 19 Jun 20 Jun 21

Harrisburg      97/1957     98/1994     98/1931     98/1923
Williamsport    97/2018     96/1929     101/1923    97/1933
State College   94/1923     94/1931     94/1953     94/1988

&&

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

&&

$$

SYNOPSIS...Fitzgerald
NEAR TERM...Fitzgerald
SHORT TERM...Fitzgerald/NPB
LONG TERM...Bauco
AVIATION...Martin
CLIMATE...NPB