Harrisburg, Pennsylvania 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

167
FXUS61 KCTP 050202
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1002 PM EDT Sat Jul 4 2026

.WHAT HAS CHANGED...
* Severe thunderstorms have moved off to the east. Watch
  cancelled.

&&

.KEY MESSAGES...
1) Storms have moved east and left us in the stable air for the
night.

2) Chances of showers and storms become more widespread on
Sunday and Monday, bringing both severe and flooding concerns
for the end of the weekend and into the first of next week.

&&

.DISCUSSION...
KEY MESSAGE 1: Storms have moved east and left us in the stable
air for the night.

Severe storms have moved to the east of the CWA, leaving quite a
bit of damage. The stable air overnight will help diminish the
showers out there now (10 PM). The wind will become light, and
fog is a good bet over most of the area due to the moisture in
and just above the ground from rain earlier. A fog advisory may
be necessary as the night goes on. Temps are already extremely
different/lower than just a couple of hours ago.

 ---------------------------------------------------------

KEY MESSAGE 2: Chances of showers and storms become more
widespread on Sunday and Monday, bringing both severe and
flooding concerns for the end of the weekend and into the first
of next week.

Recent HREF ensemble guidance and hi-res model guidance
indicate some precipitation around the area late Sunday morning
into the early afternoon hours before a general increase across
the board on shower/thunderstorm coverage. The air mass across
central Pennsylvania will be fairly moist, with HREF guidance
indicating PWATs approaching in the 1.50-1.75" range across N/W
PA with some locations in SE PA approaching 1.75-2.00" PWATs by
the afternoon and evening hours. For reference to climatology
if this solution pans out, this would be in the 90th to 95th
percentile for PWATs for the beginning of July. Recent NBM QPF
forecast brings 1.50-2.00" of rainfall into portions of SE PA on
Sunday, with heaviest rain expected in the afternoon and
evening hours with some heavier rain considering overnight into
Monday morning. This heavy rain signal is matched in recent HREF
ensemble guidance, with 24 hour LPMMs outlining some spot
amounts between 3-4" for this same timeframe. This signal for
heavy rain will bring some flooding concerns to the more
urbanized corridors of SE PA, which is matched in the Slight
Risk for Excessive Rainfall from WPC. The main thing that would
preclude flooding concerns would be the fact that this area is
in Severe (D2) Drought based on the most recent Drought Monitor;
however, heavy rain will still very well cause instances of
flash flooding. This heavy rain signal will be in place on
Monday; however, slightly less rainfall forecast on Monday and
will have to see what rainfall this evening though Sunday brings
to the region before reading too much into this threat. There
also will be some severe threat stationed across southern
Pennsylvania, mainly south of the I-80 corridor with damaging
winds being the main concern given ample instability in place.

&&

.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
Back to aviation after brief break from earlier aviation duties.

Main change was to adjust fcst to current obs and radar. Severe
storms in the MDT area and just a few minutes away from LNS.

Earlier information below.

For the 18Z TAF package, main change is to slow down the start
time of showers and storms. This based on a similar pattern
to what we had yesterday. Also lower dewpoints and more of a NW
wind so far today. Yesterday storms fired up across the north
during the early to mid afternoon hours, and stayed northeast of
MDT and LNS.

Another set of storms moved eastward into central PA toward UNV
by late evening.

The airmass so far today has dewpoints lower than the last few
days. Maybe not a huge factor for humans, but storms are happy
with the more humid airmass, thus a slight change in moisture
can lead to large changes in the outcome.

The other change was to add more detail later tonight into
Sunday, where some fog and lower CIGS possible, mainly in
spots like BFD and IPT and in areas that get some rain.

Lower CIGS Sunday could occur and linger behind the front if
widespread showers form early enough, before heating takes hold.
Poor conditions could occur from time to time right into Tue,
before some improvement by mid week.

Outlook...

Mon-Tue...Restrictions possible in A.M. fog and P.M. T-storms.
Wed-Thu...Improving conditions expected.

&&

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

&&

$$

WHAT HAS CHANGED...Dangelo/Beaty
KEY MESSAGES...Dangelo/Beaty
DISCUSSION...Dangelo/Beaty
AVIATION...Martin