Lower Macungie, Pennsylvania 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

128
FXUS61 KPHI 150716
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
316 AM EDT Fri Aug 15 2025

.SYNOPSIS...
A cold front passes through the region early this morning, then
gets hung up over the Mid-Atlantic through the weekend. High
pressure over the northern Province of Quebec builds down into
the Canadian Maritimes and Northeast later today through
Saturday before departing Sunday. A cold front passes through
the region Sunday night then becomes stationary over the Mid-
Atlantic into the new week. High pressure builds in from the
north through the middle of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
The front that crossed the area later Thursday is now offshore
with high pressure building in behind it. Slightly cooler and
somewhat drier air is filtering in across the area. This trend
will continue today with lower moisture and lower chances for
showers/tstms across northern NJ and NE PA. Across the southern
areas, the developing onshore flow will keep higher RH values
for Delmarva and SE PA. There will still be enough
heat/instability to cause scattered showers/tstms to develop
later this afternoon. The latest NBM pops were a bit lower than
previous fcsts and are mostly in the 20 to 30% range. The
coverage will be less than on Thursday. There is still potential
for excessive rain with tstms especially near Chester County,
PA. Highs today will be 85 to 90 degrees.

Tonight, any shower/tstms activity will diminish by sunset.
Skies will become partly cloudy during the overnight period most
areas. Across southern NJ and Delmarva, some low clouds may
push in from the ocean late. Lows will be in the mid/upper 60s
across the northern areas while readings in the low 70s will be
found across metro Philadelphia and Delmarva. Light E/SE winds
expected.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
High pressure over the Canadian Maritimes builds down into the
Gulf of Maine on Saturday. Onshore flow will keep a fairly
humid, though not necessarily hot, airmass over the area. Highs
will top off in the mid to upper 80s with surface dew points in
the upper 60s to low 70s. Some shortwave energy approaches from
the west in the afternoon and may spark off some afternoon
showers and thunderstorms mainly well north and west of
Philadelphia. These storms do not look to be widespread or
organized, and the severe thunderstorm and flash flood threat is
minimal. PoPs will be capped at 20-30 percent.

Drier air then filters down into the region starting Saturday
night. Cooler with lows in the 60s to around 70.

On Sunday, high pressure over the Gulf of Maine builds down
into the western Atlantic. A cold front approaches from the west
and looks to pass through the region Sunday night. A southwest
flow increases ahead of the approaching front, and temperatures
will take a run at 90 once again with dew points around 70.

With the passage of that cold front, there does not look to be
strong shortwave energy, and the base of the upper trough will
remain well north of the area. PoPs will once again be capped at
20-30 percent, and storms do not look to be widespread or well
organized with minimal severe thunderstorm or flash flooding
threats.

Drier air filters down into the region Sunday night with dew
points dropping into the 60s and lows in the upper 60s to low
70s.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
The aformentioned cold front will become nearly stationary over
the Mid-Atlantic through the middle of the week. High pressure
south of Hudson Bay Monday morning will build east into the
Province of Quebec, then down into the Canadian Maritimes and
Northeast Tuesday before moving out to sea Wednesday. An upper
trough will lie over the Northeast during the time.

A somewhat cooler and drier airmass will build into the region.
Surface dew points will mainly be in the lower 60s during this
time (a far cry from the 70s) with highs in the upper 70s to
around 80 and lows in the 60s. Mostly dry Monday and Tuesday,
and then scattered showers and thunderstorms will begin to
impact the area starting Tuesday night and continuing through
Thursday as shortwaves move in from the west.

Potential impacts from what is currently Tropical Storm Erin,
but will soon become Hurricane Erin, including a high risk for
rip currents and at least minor coastal flooding, may affect the
area starting as early as Monday and lasting into Thursday.
Please refer to the National Hurricane Center for more details
and stay tuned to the local forecast.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Today...A little patchy fog early then VFR conditions expected
much of the day. Scattered showers/tstms will develop after 18Z
with S/W areas favored so we`ve included VCSH in the 06Z TAFS at
most sites. We`ll consider VCTS with the 12 TAFS with KILG
probably bing the most likely site. NE winds turning E late.
speeds mostly 5 to 10 knots. Medium/high confid overall.

Tonight...Any shower/tstm activity will have diminished by 00Z
with VFR expected or awhile after that. It`s possible that with
the onshore flow that low clouds may arrive towards dawn and IFR
CIGS are possible then. This may be added to the 12Z TAFS for
KACY/KMIV. Good confid overall, but less with the possibility of
the IFR conditions.

Outlook...

Saturday through Saturday night...VFR.

Sunday through Sunday night...Generally VFR, but scattered
afternoon and evening SHRA/TSRA may result in brief sub-VFR
conditions.

Monday through Tuesday...VFR.

&&

.MARINE...
Winds and seas remain below SCA levels today and tonight. While
fair weather is expected overall, a few late afternoon or early
evening showers/tstms could develop (20%) across Delaware Bay
and perhaps into the southern Coastal waters. Winds will back
from N/NE to E thru the day with speeds around 10 knots.

Outlook...

Saturday through Sunday...Sub-SCA conditions.

Monday through Tuesday...Potential SCA conditions due to the
approach of what is currently Tropical Storm, and will soon be
Hurricane Erin. Elevated winds and seas will develop and should
last into at least Thursday.

Rip currents...

Today, northeast winds will turn east this afternoon, generally
around 10 mph. Breaking waves will be 1 to 2 feet with a light
easterly swell with a period will be around 8 seconds. As a
result, there is a LOW risk for the development of dangerous and
life threatening rip currents at the Jersey Shore and at
Delaware Beaches today.

For Saturday, northeast winds will be around 10 mph with
breaking waves around 2 feet. There will be a light easterly
swell with a period of 4 to 5 seconds. As a result, there is a
LOW risk for the development of dangerous and life threatening
rip currents at the Jersey Shore and at Delaware Beaches on
Saturday.

For specific beach forecasts, visit weather.gov/beach/phi

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...None.

&&

$$

SYNOPSIS...MPS
NEAR TERM...OHara
SHORT TERM...MPS
LONG TERM...MPS
AVIATION...MPS/OHara
MARINE...MPS/OHara