Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 261706
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
106 PM EDT Tue Mar 26 2024

.SYNOPSIS...
An upper level ridge will move offshore today as an upper trough
approaches from the west. A slow moving cold/occluded front
will cross through the state Thursday night. A weak low
pressure system approaching from the midwest will likely track
across Pennsylvania Saturday, followed by a more significant low
early next week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Tranquil conditions prevailing early today thanks to sharp
ridge axis along the mid Atlantic coast. Winds stayed up
overnight over the higher terrain of the Alleghenies thanks to
moderate pressure gradient and freshening southerly winds above
the boundary layer. Model soundings support gusty winds of 25 to
35 mph over the ridges this morning. Otherwise, clear skies and
light winds elsewhere are resulting in a cool morning with
widespread predawn temperatures in the lower to middle 30s over
the Middle to Lower Susq and parts of the SC Mountains and
Laurel Highlands and 40s elsewhere.

Clouds are increasing from the west as the aforementioned upper
ridge is nudged towards the coast and upper trough approaches
the Ohio Valley with increasing deep layer moisture. Central PA
will be caught in between a squeeze play between the approaching
upper trough and backing marine layer stratus from the Atlantic.
Deepest Atlantic moisture should remain just east of my forecast
area. Overnight model guidance continues to indicate falling
heights and surging deep layer moisture along the low level jet
supporting showers over the Allegheny Plateau by early evening.
Farther east, model soundings indicate the western periphery of
maritime influence will be near or slightly east of the area
through this afternoon. In between, much of central PA will
manage a partly sunny and dry day. Leaning slightly cloner than
NBM guidance for maxes in the east due to maritime influence and
easterly flow. Highs should range from the low to mid 50s over
the western half of the forecast area, to the upper 40s over the
higher terrain of Sullivan/Schuylkill counties.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
Little change from previous expectations for tonight as a
broken band of showers should slowly shift east across the
region along the axis of the low level jet. The strongest large
scale forcing and highest POPs should occur over the NW Mtns
Tuesday evening associated with the passage of a lead shortwave
over the Eastern Grt Lks. Waning large scale forcing behind this
feature will result in lower POPs further east. Ensemble plumes
indicate rainfall by Wed AM will be generally less than 0.10
inches. Cloud cover, an active southeast breeze and surging low
level moisture should result in a much milder Tues night than
recent nights with lows in 40s.

A weakening cold/occluded front is progged to push into the
region late Wednesday. Falling heights and surging pwats ahead
of this feature will keep the scattered showers in forecast for
Wednesday. A few lingering showers are likely to accompany the
cold/occluded front, as it slowly pushes east across the region
Wed night.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
All medium range guidance develops an area of low pressure on
the stalling front over the southeast coast, then tracks it
northeast late this week. Model guidance has trended east with
the track of this storm over the past few cycles, with a 40%
chance of greater than 0.50 inch in 24 hours ending 18z Thu
confined to far eastern Lancaster county (higher probs east of
there).

Northwest winds will pick up on Fri as the pressure gradient
tightens behind the departing low pressure system. Wind gusts up
to 40 mph are progged across the southeast and Laurel
Highlands. With high pressure building in, large scale
subsidence will lead to mostly sunny skies and low dewpoints Fri
afternoon. The combination of gusty winds and min RH values
near 30% could present fire weather concerns, but temperatures
in the 50s and marginal fine fuel moisture may be limiting
factors.

A weak wave of low pressure tracking across PA could
produce a bit of light rain Sat or Sat night. Beyond that, a
somewhat more substantial rainfall is possible early next week
associated with a stronger low approaching from the midwest.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
VFR conditions will continue for the next few hours, but all
guidance does indicate that MVFR ceilings will begin to work
their way in across the Lower Susquehanna Valley into the
late morning. At the same time, high clouds will continue to
move in from the west and will gradually lower through the day
with MVFR conditions expected for western sites by the late
afternoon/early evening. VFR conditions will hang on the longest
at AOO and UNV, but lower ceilings will arrive for those sites
by 00Z Wednesday.

Ceilings will continue to lower into the evening, and the
HREF/SREF suggest a 60-90% chance of IFR ceilings for most of
the area after 00Z. LIFR ceilings also appear likely after 06Z
for MDT and LNS. Showers will begin to move in from the west
this evening and will slowly spread eastward into Wednesday
morning.

Low level wind shear will continue for western sites into the
early afternoon as a 40 to 50 knot southeasterly low level jet
remains in place.


Outlook...

Wed...Rain/low cigs possible.

Thu...Lingering rain and reduced cigs possible S/E.

Thu night-Fri...Improving conds.

Sat...Light rain possible.

&&

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

&&

$$

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


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