Lancaster, Pennsylvania Weather Forecast Discussion

381
FXUS61 KCTP 131906
AFDCTP
Area Forecast Discussion
National Weather Service State College PA
306 PM EDT Sat Sep 13 2025
.SYNOPSIS...
* Mid-to-upper level trough will bring the outside chance of a
  shower across northern Pennsylvania this afternoon/evening.
* High confidence in dry conditions through into the middle of
  next week, with no precipitation mentions through Tuesday.
* Temperatures are expected to remain above average into the
  last week of astronomical summer.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Current radar outlines weak returns across Warren County and
points northwest as a weak mid-to-upper level trough approaches
central Pennsylvania. Rain will have to continue to fall
through relatively dry air, with ~30F dew point depressions at
BFD; however, cannot rule out a stray shower generally for
points north of the Interstate 80 corridor over the next couple
of hours. Odds continue to hover around the ~10% mark for
measurable rainfall due to the low-level dry air. Expansive
high-level clouds are expected to thicken with the
aforementioned trough in the near-term before beginning to clear
out overnight. Fog potential is expected to be lower tonight
due to lingering cloud cover; however, some valley fog formation
will remain possible overnight into Sunday morning.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
Upper-level pattern continues to look favorable for a
continuation of dry conditions through Monday with little in the
way for precipitation outside of mentions in the near-term.
This pattern will also allow for slightly above average
temperatures throughout much of the near-term with partly sunny
skies expected throughout the day and some potential for
radiational cooling in the overnight period with patchy valley
fog into Sunday and Monday mornings.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
The bulk of model guidance keeps fair conditions on Tuesday
with a closed low stationed south/east of central Pennsylvania
will bring some potential for precipitation chances on Wednesday
and into the second half of the week; however, there remains a
fair amount of spread in model guidance with respect to this
feature especially given the upper-level pattern that typically
will be difficult to break down. A fair amount of uncertainty
remains progressing on Friday and into the first half of the
weekend with respect to an approaching area of low pressure from
the Midwest; however, given model discrepancies have decided to
keep NBM PoPs through Saturday.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
Increasing mid-to-high level clouds are present on current
satellite with some radar returns across far northwestern
Pennsylvania. Low-levels in recent model guidance (and
observations) remain fairly dry, thus have kept all
precipitation mentions out of the 18Z TAF package. Some
thickening of the cloud layer is expected over the next 2-6
hours; however, all guidance points to VFR conditions prevailing
throughout the TAF package. Valley fog potential overnight is
progged to be slightly lower compared to last night, with
lingering high-level clouds expected to limit this potential.
Outlook...
Mon-Tue... VFR with AM valley fog.
Wed-Thu...Generally VFR, some SHRA possible (10-20%) SE PA.
&&
.FIRE WEATHER...
Our dry spell is getting pretty long. The MinRH for many days
will dip into the 40s with some 30s over the Alleghenies on
Sunday. There should be a gradual climb in RH/dewpoints through
the coming week, but an extremely small chance of appreciable
rainfall through the next 7 (plus?) days. Leaves are starting to
fall, whether due to drought stress or the regular autumnal
schedule. The leaves add more fine fuels to the mix. On the
other side of the coin, the wind will be light through that time
with high pressure overhead. So, we aren`t looking at red flag
conditions, but it is very crispy.
&&
.CLIMATE...
Astronomical fall officially begins with the autumnal equinox
on Monday, September 22, 2025 @ 2:19 p.m. EDT. The Autumn 2025
season will last 89 days, 20 hours, and 43 minutes. Daylight
saving time will end just after Halloween with clocks falling
back at 2 a.m. Sunday, November 2, 2025.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...NPB
NEAR TERM...NPB
SHORT TERM...NPB
LONG TERM...NPB
AVIATION...NPB
FIRE WEATHER...Dangelo
CLIMATE...Steinbugl

NWS CTP Office Area Forecast Discussion