NWS Forecast Discussion

FXUS61 KCTP 251124

Area Forecast Discussion
National Weather Service State College PA
724 AM EDT Sat Jun 25 2022

Weak high pressure overhead will slide east and start to direct
warmer air in from the south today and Sunday. A cold front is
expected to pass through Sunday night and early Monday, and
provide showers and thunderstorms. Drier and somewhat cooler
weather should follow for later Monday and Tuesday as high
pressure builds in from the west.


The valley fog will linger thru mid morning in the deepest
valleys and over the middle Susq and Juniata valleys.
Otherwise, upper level ridging should support fair and warm
conditions Saturday. Given the progged weak capping inversion,
can`t completely rule out a late day shower developing over the
Laurels or far east (Sullivan/Columbia/Schuylkill Counties).
Will top PoPs at 20pct near the highest ridge tops there.

Expect highs to be several degrees warmer today vs Fri in most
place, esp the NW, as the light wind finally turns southerly.
Mid to upper 80s are expected in most locations.


SPC and WPC continue MRGL risks for Svr Wx and Ex Rain for
Sunday and Sunday night. Mean CAPE values on the HREF get near
1000J/kg around noon. A short wave trough and associated sfc
feature will arrive just ahead of the cold front. The forcing
and lift could work with the heat and terrain of the Laurels and
western Alleghenies to pop storms there a little quicker than
fcst. But, the main show remains later in the aftn and evening
when the front moves through.

After a fair and warm Saturday night, focus will shift to a
deepening upstream trough over the Grt Lks. Falling heights,
combined with heating of an increasingly moist/unstable air
mass, should result in developing convection during the PM
hours. Model 850mb temps near 17C support highs from the mid 80s
over the higher terrain of the Alleghenies, to around 90F in
the Susq Valley.

Weak mid level flow and associated deep layer shear, combined
with only modest ensemble mean capes, suggest a low risk of
organized severe weather late Sunday for most of central Pa.
However, SPC has painted a MRGL risk over northwest Pa, where
models indicate a late day surge of low level moisture and
higher capes, combined with slightly strong mid level winds. NBM
POPs appear reasonable late Sunday, ranging from around 70pct
over Warren County, to around 10pct over Lancaster County.


Latest guidance indicates the fropa and highest POPS (80-90pct)
will occur Sunday night into early Monday morning. Depending on
the speed and amplification of the associated northern stream
upper shortwave, the front could hang up temporarily across the
Lower Susq Valley into Monday afternoon. Otherwise, expect
increasing sunshine and breezy conditions, as much drier air
works in on northwest flow.

Dry and cool weather with low humidity appears very likely late
Monday through Tuesday night, as high pressure and associated
low-pwat airmass builds across the region. Model soundings
show very dry air above a weak inversion Monday and Tuesday
afternoons, indicating an opportunity to undercut NBM dewpoints.
Nearly ideal conditions for radiational cooling appear likely
Monday night with surface high directly over the region. Min
temps in the 40s appear likely over the Alleghenies.

All medium range guidance supports a warming trend Wed-Fri, as
high pressure passes off of the east coast. A weak,
moisture-starved shortwave is progged to track across the area
late Wednesday. Can`t rule out a PM shower or TSRA with this
feature, but latest ensemble plumes don`t support POPs any
higher than about 10 pct.

Falling heights ahead of an upstream trough, combined with
surging pwats ahead of the approaching cold front, will bring a
chance of PM convection next Friday, especially over the
northwest counties. Ensemble mean 850mb temps of 17-18C indicate
highs will likely peak around 90F in valleys locations Friday


Fog is quickly lifting out this morning, as of 11Z. Expect a VFR
day with light winds and mostly clear skies.


Sun...Late day and night-time showers and thunderstorms
possible, along with associated restrictions.

Mon...Morning showers and associated restrictions possible.

Tue-Wed...Mainly VFR.




NEAR TERM...Dangelo
SHORT TERM...Lambert/Fitzgerald/Dangelo
LONG TERM...Fitzgerald

NWS CTP Office Area Forecast Discussion