Lancaster, Pennsylvania 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

682
FXUS61 KCTP 111422
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1022 AM EDT Fri Apr 11 2025

.SYNOPSIS...
*Cloudy, chilly and wet end to the week/start to the weekend
*Drying out Sunday with some sun and milder temperatures
*Warmer with late-day rain showers Monday followed by windy and
 cooler weather next Tuesday and Wednesday

&&

.NEAR TERM /THROUGH TONIGHT/...
Morning forecast holding well as moist southeast flow maintains
widespread low clouds and areas of light rain/drizzle/ridgetop
fog this morning with inverted sfc trough over the Alleghenies.

A deep layer 500mb trough evolving over the eastern Great Lakes
southward into the central Appalachians will amplify over the
Mid Atlantic region today as an jet streak rounds the base of
the trough and lifts northeastward along the coastal plain. Max
QPF response tied to favorable left exit region jet dynamics
and strengthening fgen forcing on the NW side of developing sfc
low along the VA/NC coast will be across the southeastern zones
with 0.75-1+ inch rainfall totals fcst near and southeast of
I81. Latest HREF indicates highest probability for >1" is near
and southeast of US30 corridor in Adams/York/Lancaster County.

Light rain/drizzle will continue over the northwestern half to
2/3 of the forecast area through tonight with QPF totals of less
than 0.50 inches. Thermal profiles tonight will be cold enough
to support a rain/wet snow mix over the higher elevations in the
northeastern quadrant of the forecast area, but sfc temps above
32F suggest any slushy coating <0.5" will be limited to non-
paved sfcs.

Cold air damming, combined with low clouds and rain, will
result in a very chilly end to the week by mid April standards
with highs in the mid 40s or 8 to 15 degrees below the historical
average.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
As the surface low tracks from the DelMarVa off the coast, the
llvl flow will back to the north. While QPF amounts will trend
substantially lower on Saturday (<=0.10"), residual wrap around
moisture within the cold conveyor belt/TROWAL on the northwest
periphery of the closed upper low will result in another chilly
and damp day across CPA to start the second weekend of April.
We trimmed daytime maxTs a bit in response to this cool pattern
setup.

Precip tapers off from NW to SE Saturday night. However, low
clouds are likely to get trapped beneath the subsidence
inversion associated with high pressure building into CPA into
early Sunday morning. Min temps will be similar to Friday night
in the 35-40F range.

More seasonable weather is expected on Sunday with a mix of sun
and clouds as high pressure migrates over the Keystone State.
Max temps are projected to climb by +10-15 degrees vs. Saturday
with highs in the 50-60F range or very close to daily climo. A
warm front lifting northeast from the Ohio Valley could provide
more clouds than fcst especially into Sunday night and maybe
even some light rain showers over southwest PA. Lows also trend
warmer vs. Saturday night with the largest MinT24hrChange of +5
to +10F across the western mtns where southerly return flow will
be most active into Monday.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
A return southwest flow between the exiting surface high and an
approaching cold front over the Grt Lks should result in a warm
Monday with maxtemps several degrees above climo.

The fast-moving cold front is progged to sweep across central
PA Monday afternoon/evening, accompanied by a round of showers
for most of the area. Strong large scale forcing and decent
moisture return support high POPs but relatively low QPF per
the latest EPS plumes (ensemble mean qpf 0.1-0.4 inches)

A digging upper trough over the E Grt Lks will then likely be
accompanied by blustery conditions into midweek with
temperatures falling well below mid April normals by Wednesday.
The arriving airmass should be sufficiently cold to produce lake
effect rain and snow showers over primarily the Allegheny
Plateau into early Wed.

Fair and seasonable weather looks likely next Thursday, as the
deep upper trough lifts out and surface ridging arrives.
However, an approaching warm front could potentially spread
showers into the region by Thursday night.

&&

.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
Late morning update.

Main issue is CIGS have been on the decrease this morning,
TAFs adjusted for this.

Area of rain pushing northward toward the MD, PA border.
Rain will be in the MDT and LNS in a few hours.

Earlier discussion below.

Isolated rain showers continue to pop up across the region,
their impacts sporadic given the light precipitation and are
mainly progressing over western Pennsylvania this morning. A
mixture of IFR and MVFR is currently being observed across all
airfields. A thick cloud deck is expected to persist overhead
for the entire day, keeping skies overcast with low ceilings.

A near stationary front parked in western Pennsylvania and
draped over the Ohio Valley, along with the associated surface
low, will continue to keep the region supplied with abundant
moisture throughout the day today. More scattered showers are
likely across much of the state throughout the morning and into
early afternoon. Rain will increase in spacial coverage across
the Lower Susquehanna Valley sites of MDT and LNS by late
afternoon today, with steady rain likely to persist beyond 00Z
Saturday. Little to no improvement to flight categories is
expected for the next 24 hours.

Outlook...

Fri-Sat...Periods of rain with sub-VFR likely.

Sun...Improving conditions/trending VFR.

Mon...VFR. Clear early. Increasing clouds late.

Tue...Sct rain throughout the day. Sub-VFR possible.

Wed...Iso snow in NW. Elsewhere VFR/no sig wx.

&&

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

&&

$$

SYNOPSIS...DeVoir/Steinbugl
NEAR TERM...DeVoir/Fitzgerald/Steinbugl
SHORT TERM...Fitzgerald/Steinbugl
LONG TERM...DeVoir/Fitzgerald
AVIATION...Martin/Bowen