Latest Area Forecast Discussion for Central PA

Here is the latest Area Forecast Discussion for Central PA

This text statement is the latest forecast reasoning from the NWS in State College, PA

See the links at the bottom of the page for previous issuances/versions of the statement as well as our other text statements.

000
FXUS61 KCTP 180545
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
145 AM EDT Sat May 18 2024

.SYNOPSIS...
A decaying frontal system will keep showers over mainly western
and central portions of central Pennsylvania overnight. Low
pressure passing well to the south of Pennsylvania will bring
additional showers to central Pennsylvania into Saturday
afternoon, followed by high pressure and dry weather arriving
for Sunday. Mainly dry conditions are expected through the
middle of next week.

&&

.NEAR TERM /THROUGH TODAY/...
Decaying frontal system and upper level shear axis sagging into
western and central PA this evening has maintained scattered to
numerous showers through late evening. Leading edge of shower
activity has been very slow to progress eastward tonight, but a
weak 850 mb jet and persistent WSW flow aloft associated with 5H
shear axis moving into western PA is finally nudging the showers
farther east late this evening. Far eastern/southeastern areas
may not see showers arrive until a few hours before sunrise, and
even then they will be quite light.

Aforementioned shear axis will continue to maintain sct to
numerous showers overnight, with moist southeast upslope flow
enhancing showers in favored terrain while also supporting low
clouds/cigs and fog. Should breaks develop over my northwest
counties, dense fog could develop overnight, but confidence at
this time is low for the NE Ohio cloud breaks to overspread the
NW Mountains through midnight. More likely that fog thickens in
the predawn hours and midnight shift will need to consider fog
headlines overnight. Lows in the 55-60F range are +5-15F above
mid May climo with the larger departures across the western and
northern Alleghenies.

&&

.SHORT TERM /TONIGHT THROUGH MONDAY/...
No changes seen for Saturday as we`ll have yet another weekend
day to start the weekend. The morning and afternoon will
feature plenty of clouds, periods of light rain/showers, and
areas of fog. Hires model data focuses the bulk of the rain
early in the day, becoming more scattered through the afternoon
into the evening. Cool air damming (CAD) pattern with moist east
southeast flow will result in highs of 60-65F across the
southeast half of the CWA (5-10F below climo), and warmer
readings over the NW mountains aided by downsloping with 70-75F
expected there. Continued to temper NBM with blend of raw hires
model data given typical downside risk for cooler temps in this
type of CAD pattern setup.

Sunday is looking increasingly nice with high pressure
eventually allowing a good deal of sunshine throughout and
salvaging the second half of the weekend. Decreasing deep layer
moisture and a northerly wind component along with ridging at
the sfc and aloft should help highs recover nicely with temps
around 80F fcst in the NW Alleghenies and mid to upper 60s
elsewhere.

We are likely to see some areas of fog both Saturday night and
Sunday night, and temps will continue to trend warmer with dry
weather persisting into early next week with highs on Monday
reaching the upper 70s to mid 80s.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
A dry start to the extended period will be likely with high
pressure ridging building over the mid-atlantic region and a
deep surface low parked over the central plains. High pressure
and dry air will stay in place through Tuesday before the upper
level trough pushes them both out by Wednesday afternoon. 850mb
temps of near 16C along with surface warm air advection suggest
high temperatures could reach the mid 80s on Tuesday and
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
given the aforementioned WAA bringing greater instability.

After the front moves through, considerable uncertainty exists
in terms of how much and how frequent rain will be. A chance of
showers remains in place through the end of the week despite
zonal flow aloft providing little in the way of synoptic
forcing. The next chance for a widespread soaking rain will come
during the weekend with a center of low pressure developing
across the Ohio Valley by Friday afternoon.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
IFR cigs are likely (> 80% confidence) over the western
highlands (BFD, JST) overnight, with borderline IFR/MVFR cigs
expected over the central mtns (AOO, UNV). Farther to the east,
the Susq Valley should eventually see cigs drop to MVFR during
the pre-dawn hours.

IFR (or borderline IFR/MVFR) cigs will be dominant areawide
through the morning hours, along with periods of light rain.

Patchy light rain will persist into the afternoon to the
southeast of the Allegheny Front, along with low-end MVFR cigs.
For the western highlands, cigs should improve to MVFR (perhaps
even low-end VFR) this afternoon although scattered rain
showers are possible.

Outlook...

Sun...Morning low cigs/fog possible. Becoming VFR by afternoon.

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

Tue...Predominantly VFR, w/ no sig wx expected.

Wed...Sct to widespread SHRA/TSRA return.

&&

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

&&

$$

SYNOPSIS...DeVoir/Steinbugl
NEAR TERM...DeVoir/Steinbugl
SHORT TERM...DeVoir/Steinbugl
LONG TERM...DeVoir/Bowen
AVIATION...Evanego

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