Lancaster, Pennsylvania 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

827
FXUS61 KCTP 052348
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
748 PM EDT Fri Sep 5 2025

.SYNOPSIS...
* A cold front will move through late tonight and Saturday with
  several rounds of showers and a chance of a gusty thunderstorm
  across the eastern half of the state.
* High pressure builds in for Sunday through next week, with
  abundant sunshine, morning fog, and dry conditions.
* Frost potential returns Monday and Tuesday mornings across the
  typical cold spots in northern PA.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
A seasonably warm and pleasant day is ongoing across the
Commonwealth with only a few fair-weather clouds and wildfire
smoke aloft filtering an otherwise sunny day. Southwest winds
will frequently gust 20 to 30mph this afternoon, helping advect
mild temperatures and increasing moisture ahead of an
approaching cold front.

Highs this afternoon will range from the upper 70s in northern
PA to near 90 across the southern tier. Dewpoints in the 60s in
the Susquehanna Valley will certainly feel humid relatively to
the cool/dry airmass we`ve had over the past couple weeks.

As day turns to evening, the cold front will begin moving into
western PA as a wave of low pressure moves northeastward along
it. Isolated showers may persist throughout the night along the
front, which will be draped from southwest to northeast across
PA, but the extent/intensity of showers should follow the
typical nocturnal minimum as instability wanes.

Severe weather is likely in the Ohio Valley late this evening,
and some of the remnant storms could bring gusty showers into
the Laurel Highlands tonight. A MRGL risk of severe weather is
in place, indicating that a stronger storm or two is possible.
Instability will not be all that impressive and shear is
marginal, but folks heading out to Friday night football should
keep an eye on the skies in southwest PA, especially toward the
end of football games.

Increasing clouds are expected from west to east tonight,
helping limit the risk of fog for most of the area, but
southeast PA should stay clear the longest (and will have the
highest dewpoints), so fog is possible in parts of Lancaster,
Lebanon, and Dauphin Counties. Lows by daybreak Saturday will be
quite variable - upper 40s behind the cold front in northwest PA
to upper 60s in the southeast. Rain showers will likely be
ongoing before dawn across much of Central PA, with perhaps a
rumble of thunder or two possible on the leading edge of the
line.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
Showers and storms will continue on Saturday as the cold front
pushes east. Ongoing morning showers should limit the severe
threat for most of the area along, north, and west of the
I-99/I-80 corridor, but rain will likely dampen outdoor
tailgating festivities. As the front moves east, the threat for
severe weather will increase thanks to an increasingly favorable
shear/instability environment across eastern PA. The SPC has
upgraded a portion of the Lower Susq Valley into the northeast
to a Slight risk for SVR TSRA thanks to ample deep layer shear
and sufficient instability of around 1500 J/kg of MLCAPE. With
the current expected frontal timing, the threat of storms should
be confined to the far southeastern periphery of our forecast
area (with the better chance for storms farther east up into New
England), but a slightly slower progression of the front could
lead to a more extensive threat for portions of the Lower
Susquehanna Valley.

Behind the front, clouds will likely hang around for awhile as
the moisture at mid-levels is a bit slower to clear. Lake effect
rain showers will ramp up downwind of the lake as well thanks to
west-northwest winds carrying cool air over the relatively
warmer waters. Highs on Saturday afternoon will once again
exhibit quite a spread, only in the low to mid 60s in the
cloudy/rainy/post frontal airmass in the northwest and getting
into the mid 80s ahead of the front and before the storms in the
Lower Susquehanna Valley.

Valley fog is likely in the typical spots across the north and
west on Sunday morning in the wake of the front where air-water
temperature differences will be sufficiently high to promote
dendritic fog formation. With lower dewpoints building in behind
the front, lows in the upper 30s could be observed in far
northwest PA and most spots will fall into the mid 40s to upper
50s farther southeast.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
After the cold front sweeps through, another fall-like pattern
will settle in for the second half of the weekend and into next
week. The airmass moving overhead will be the coolest of the
season so far. Highs in the 60s and 70s will pair with lows in
the 30s to 50s. Frost or freeze conditions seem like a good bet
for the typical cool spots in northwest PA early next week along
with river valley fog. Abundant sunshine and dry conditions are
favored, with temperatures gradually increasing each day through
the end of next week thanks to a building ridge aloft.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
Widespread VFR conditions were found across Central PA at 00z.
A few rain showers were popping up across northwestern PA, and
have maintained a PROB30 for -SHRA at BFD through this evening.

Scattered showers will drift into southwestern PA late this
evening and could impact JST into the early overnight. As the
night progresses, additional clouds and showers will push into
southwestern PA and could reach the central mtns (AOO, UNV,
IPT) by daybreak. Across the Lower Susq Valley, fair skies and
lighter winds could lead to some fog formation in the vicinity
of MDT and LNS by daybreak on Sat. (Of note, have eased off of
the low cigs/fog for IPT in the pre-dawn hours on Sat, as mid
and high level clouds should be on the increase and we`re
starting the night with a much larger dewpoint depression than
we saw last evening. Still worth monitoring though.)

Scattered showers remain possible into Saturday morning across
western PA and into the central mtns. By afternoon, we could see
additional SHRA/TSRA develop across southeastern PA. This
activity may develop just east of the Lower Susq Valley, but
have hinted at the possibility with a PROB30 for -TSRA at LNS
Sat aftn.

Outlook...

Sun-Mon...Clearing with primarily VFR conditions. Breezy.

Tue-Wed...Clear.

&&

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

&&

$$

SYNOPSIS...Lambert/Banghoff
NEAR TERM...Banghoff
SHORT TERM...Lambert/Banghoff
LONG TERM...Banghoff
AVIATION...Evanego