011
FXUS61 KCTP 260057
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
857 PM EDT Tue Jun 25 2024

.SYNOPSIS...
High pressure will drift off of the Mid Atlantic Coast tonight,
allowing increasing moisture to return to the region.

Heat will build again by Wednesday leading to a chance of
thunderstorms by late in the day and Wednesday night as a cold
front pushes through the state.

Dry weather with comfortable humidity on Thursday and Friday
will be followed by another cold front late Saturday or early
Sunday of next weekend.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Early evening water vapor loop shows a potent shortwave tracking well
north of PA through the St Lawrence Valley. Visible satellite
loop at 00Z shows cumulus with decent vertical development along
the trailing low level jet from KERI to KBUF. Warm advection
along this feature could potentially produce a shower/tsra
across the NW Mtns late this evening. Otherwise, tonight looks
quiet with varying amounts of mid and high level cloudiness
overspreading the state ahead of an upstream trough over the
Plains.

An active southwest breeze will draw steadily rising dewpoints
into the region tonight, resulting in much warmer conditions
than last night. See no reason to deviate from NBM mintemp,
which range from the mid 60s over the NW Mtns, to the low 70s in
the Lower Susq Valley.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY NIGHT/...
Diurnal heating of an increasingly moist/unstable airmass,
combined with falling heights ahead of the upstream trough, will
result in developing convection during Wed afternoon. A ribbon
of relatively strong mid level winds of 40-50kts, combined with
progged moderate instability across Central and Southern PA,
suggests organized convection and locally severe weather can be
expected across this part of the state Wed PM. Some of the
latest model guidance suggests an eastward-moving MCV could
result in a batch of strong-severe convection across Southern PA
in the 16Z-21Z time-frame, with diminished potential in the
rain-cooled air behind it. However, wouldn`t place too much
weight on this right now, as the strongest shear should be in
the late afternoon to early evening timeframe. Some of the 12Z
HREF members indicate UH values >150 across Southern PA in the
early evening, which is supportive of supercells.

Latest ensemble plumes indicates most likely aerial average
rainfall Wed PM will be around a half inch. However, isolated
amounts around 2 inches appear likely based on the latest HREF
and a combination of moderate instability and +1-2SD pwats.

Thicker clouds will likely cap temps to the upper 70s across the
NW Mtns Wed, while a decent amount of sun is anticipated across
the southeast counties based on model RH profiles. 850mb temps
support highs as warm as the low 90s across the Lower Susq
Valley. The combination of heat and humidity should result in
heat indices peaking in the mid 90s in that part of the state.

Dwindling convection from northwest to southeast is anticipated
Wed night, as the upper trough and associated cold front work
through. Large scale subsidence and the arrival of much drier
air behind the exiting cold front should then result in fair
and seasonable conditions Thursday. Surface high pressure
building over the region should result in fair and cool weather
Thu night. Fair and slightly warmer conditions are likely
Friday, as low pwats persist over PA and a return southerly flow
develops as the surface high passes off the coast.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
Predictability begins to wane by this weekend regarding the
timing/amplitude of the shortwave trough expected to move from
the Great Lakes region into the Northeast/New England. There is
some potential for stronger deep-layer flow to overspread an
increasingly moist warm sector, but details regarding the
surface pattern remain uncertain, and rather warm temperatures
aloft could limit destabilization potential. Some potential for
strong to locally severe storms could evolve on Saturday ahead
of a cold front from the Ohio Valley into parts of the
Northeast. WPC has also suggested the potential for a marginal
to slight risk of locally heavy/excessive rainfall on Saturday
with pwats surging to +2SD above normal. The timing of the
main synoptic cold front on Sunday is also uncertain with some
potential for a secondary strong/svr tstm risk.

Confidence is significantly higher concerning the arrival of
another refreshing Canadian high pressure system directing a
comfortable (less humid) airmass into CPA for early next
week...a seasonably cool and dry start to July!

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
High confidence in VFR flying through the evening into the first
half of tonight/06Z Wed. Uncertainty ramps up overnight into
early Wednesday morning with potential for showers and t-storms
moving into the airspace from the north/west. Can`t rule out
some cig restrictions in the 06-15Z window based on the latest
probabilistic guidance, but the overall pattern/low level flow
don`t provide a strong enough signal to maintain in TAFs outside
of KBFD. Confidence continues to trend lower from late Wed
morning through 18Z and beyond given highly conditional/potential
strong to severe t-storm scenario. A 40kt low level jet from
230-260 degrees will maintain LLWS at KBFD between 00-06Z.

Outlook...

Wed...Thunderstorm impacts likely.

Thu-Fri...Generally VFR.

Sat-Sun...Thunderstorm impacts possible.

&&

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

&&

$$

SYNOPSIS...Lambert/DeVoir
NEAR TERM...Fitzgerald
SHORT TERM...DeVoir/Fitzgerald
LONG TERM...Banghoff
AVIATION...Steinbugl/Bauco