Lancaster, Pennsylvania 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

432
FXUS61 KCTP 260656
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
256 AM EDT Sun Jul 26 2026

.WHAT HAS CHANGED...
Minor changes changes to the cloud cover forecast for the rest
of the day.

&&

.KEY MESSAGES...
1) A few showers over the region overnight.

2) Turning more humid and unsettled early next week with the
highest probability for showers and thunderstorms Monday
afternoon and evening and again on Tuesday and Tuesday night.

&&

.DISCUSSION...
KEY MESSAGE 1: A few showers over the region overnight.

Broad, low-level streamline convergence with its N/S axis near
the RT 219 corridor in Western PA has resulted in some showers
since earlier this afternoon. Not real warm to the west this
evening, but western areas have dewpoints into the lower 60s.
compared across most of the Susquehanna Vly. Also while winds
are rather weak, directional shear is there on the 00Z soundings
this evening.

Surface convergence becomes more focused over the eastern half
of the forecast area for tomorrow. Slightly higher dew points
will allow for instability to be a little higher than it is
today, possibly approaching 1000 J/kg in a few locations. Though
upper level forcing looks to be weak, we would expect to see at
least a few showers and thunderstorms develop during the
afternoon. This location of the fcst activity is different than
what was noted the other day. Location could shift more as we
near Sunday aft.

KEY MESSAGE 2: Turning more humid and unsettled early next week
with the highest probability for showers and thunderstorms
Monday afternoon and evening and again on Tuesday and Tuesday
night.

Main chance for widespread showers and storms will be Tuesday
into Wednesday. Fcst dewpoints not all that high for late July,
and there has been a slight downward trend with fcst dewpoints
over the last few days.

Main things supporting showers and storms is a deepening low,
and a large scale pattern that supports directional shear to
be present into next week. Models today do show a pattern change
out toward day 10, a change from recent model runs the last few
days. Thus will have to seen if this trend holds.

Earlier discussion below.

Minor modifications for this period that will be highlighted by
a warm front moving across western PA Monday afternoon/evening,
followed by a rather potent/digging mid/upper level shortwave,
that will support a sub-995 mb sfc low over the Lower Glakes and
Western NY Tuesday afternoon and evening. Latest model runs have
trended several hours or so slower compared to runs 24 hours
ago.

The timing of the favorable lift associated with the thermally
indirect, left front quad of the 80+ KT jet max moving across
the Ohio Valley, WVA and southern PA Tuesday afternoon and
evening will help to enhance a low level lee trough and
convection along it. Scattered strong to severe TSRA are likely
Tue afternoon and evening over at least the eastern half of the
CWA with a second line of TSRA likely along the cold front
across NW PA Tuesday afternoon.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
Current observations outline LIFR conditions at BFD with fog
and low cloud development currently present across the airfield
as of 06Z Sunday. This trend is likely to continue overnight
with HREF model guidance indicating the 10Z-13Z window for
improving conditions at the airfield. Elsewhere through 12Z
Sunday, it appears that JST/AOO will be most likely to
experience sub-VFR conditions based on most recent GLAMP/NBM
guidance. Not completely sold on this potential with low-level
dry air outlining dew point depression of 5F at JST and the lack
of precipitation at the airfield, thus have taken out mentions
overnight given this lower potential overall. Thus, VFR
conditions area wide outside of BFD have been sent out with the
06Z TAF package with moderate-to-high (70-80%) confidence.

Recent hi-res model solutions paint some chances for SHRA/TSRA
mainly east of UNV (IPT/MDT/LNS) during the afternoon and
evening hours on Sunday, thus have introduced some increased
mentions based on where there is increasing confidence in some
precipitation mentions in this timeframe. The lowest confidence
with respect to the 18Z Sunday to 03Z Monday timeframe is the
timing of SHRA/TSRA popping up along IPT given the wide range in
model solutions at this airfield; however, this appears to be
the airfield that could have most impact. Thus, have highlighted
the general timeframe of precipitation with SHRA and introduced
a narrower window for TSRA mentions where instability will be
the greatest and thus thunderstorm potential will be highest
despite lower coverage. Further southeast, SHRA appear to be
more likely and have nixed TSRA mentions at this time. After 02Z
Monday, signals look fairly foggy across the entire region but
lower confidence exists at AOO/JST/UNV given lower potential for
SHRA/TSRA, thus have limited mentions of sub-VFR conditions.

Outlook...

Mon...Restrictions likely in afternoon -SHRA/-TSRA. Patchy
overnight fog possible.

Tue...Restrictions likely with scattered -SHRA/-TSRA.

Wed-Thu...Restrictions possible as -SHRA/-TSRA becomes less
numerous. Patchy overnight fog possible.

&&

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

&&

$$

WHAT HAS CHANGED...Lambert/Martin/Bauco
KEY MESSAGES...Lambert/Martin/Bauco
DISCUSSION...Lambert/Martin/Bauco
AVIATION...Beaty