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907
FXUS61 KCTP 170544
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
144 AM EDT Fri May 17 2024

.SYNOPSIS...
* Rain-free for most and seasonably warmer into Friday with
  areas of fog and low clouds overnight
* Another cloudy/wet start to the weekend followed by
  marginal/gradual improvement on Sunday (Saturdayfog forecast tonight. Winds should go calm under
a ridge of high pressure centered over the Central mountains,
but the arrival of high clouds in the northwest toward daybreak
and the westward extend of low clouds in eastern PA complicate
the fog forecast in both locations. Highest confidence in some
patchy valley fog in the south central mountains up through IPT
by daybreak Friday where clear skies are most likely. Lows will
be fairly uniform in the mid 50s tonight, or +5-10F above climo
for mid May.

&&

.SHORT TERM /8 AM THIS MORNING THROUGH SUNDAY/...
Fog and low clouds could be stubborn to lift on Friday morning,
but some improvement is expected by midday with high clouds
streaming in ahead of the next weather system. Showers and a
couple of t-storms will reach the western zones around 18Z/2PM
based on the latest hires ensemble mean guidance. These showers
will continue to propagate slowly eastward tomorrow afternoon
within a relatively moist (PW 1-1.5") and marginally unstable
airmass (bulk of instability progged to stay west of the
Allegheny Plateau).

Scattered showers will continue into Saturday as southeasterly
flow helps keep overcast skies and cooler conditions in place.
Don`t think Saturday will be a washout, but it will keep the
trend of dreary Saturday weather in tact. Limited instability
under overcast skies will eliminate any chance of thunder on
Saturday outside of southwest Somerset County where a decaying
thunderstorm could traverse the region. The highest POPs/QPF
will be over the southern portion of the area Friday night into
Saturday with the highest rainfall amounts in southwest
Pennsylvania where upwards of an inch of rain is possible.
Rainfall amounts decrease with eastward extent where around a
quarter inch of rain is expected for locations along and east of
US-15. Temperatures on Saturday will top out in the 60s, though
a classic cold air damming scenario could keep highs in the
upper 50s in a few locations.

Improving conditions are likely on Saturday as an area of high
pressure over the northeast sags southward. This will promote
some breaks in the clouds and a bit milder temperatures. Some
uncertainty remains in how stubborn the clouds will be on
Sunday, but Sunday looks much better than Saturday for outdoor
plans and activities.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
*Drying trend with more sun and warmer temperatures Mon-Tue.

Decent model and ensemble signal for dry weather and more
sunshine leading to a seasonal warming trend next Monday-
Wednesday as a potential cutoff low parks over the western
Atlantic and high pressure builds overhead. Max temps are
forecast to climb back into the 75-85F range through Wednesday.

By the middle of next week, upper troughing will move across
Pennsylvania and support a better chance for showers and
thunderstorms. At the surface, there remains plenty of model
uncertainty about the timing of a cold front. The mean timing is
Wednesday afternoon, but individual models bring precipitation
as early as Tuesday evening and as a late as Thursday morning.
If the front moves through Wednesday afternoon or evening, it
could produce the first threat for severe weather in some time.

After the front moves through, considerable uncertainty exists
in terms of how much and how frequent rain will be. Have kept a
chance of showers in place through the end of the week. Fairly
high confidence in temperatures being close to average in zonal
flow.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --
At 06z, a moist low-level easterly flow is bringing low clouds
(MVFR cigs) into portions of Central PA. At the same time, some
valley fog has formed across the northwestern highlands (in the
vicinity of BFD).

Expect the low clouds (predominantly MVFR) to continue to
expand overnight. At the same time, high clouds will begin
streaming overhead from the Ohio Valley.

Ceiling bases should gradually elevate late Friday morning.
However, an approaching warm front will spread showers (and
perhaps some thunder) and lowering cigs into the western half of
PA during the afternoon and evening hours. Latest ensemble prob
charts indicate IFR cigs will become likely (80+%) by mid
evening over the higher terrain of the Alleghenies.

Cigs are expected to drop to MVFR this evening over the central
mtns, and overnight across the Susq Valley, with rain showers
continuing.

Outlook...

Sat...Restrictive lower ceilings, rain, and fog. This is a
fairly high confidence forecast.

Sun...Morning low cigs/fog possible.

Mon...Patchy AM fog possible. Otherwise, becoming VFR.

Tue...Predominantly VFR, w/ no sig wx expected.
-- End Changed Discussion --

&&

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

&&

$$

SYNOPSIS...Steinbugl
NEAR TERM...Banghoff
SHORT TERM...Steinbugl/Banghoff
LONG TERM...Guseman/Banghoff
AVIATION...Evanego