449
FXUS61 KPHI 010604
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
204 AM EDT Tue Sep 1 2026

.WHAT HAS CHANGED...
Aviation section updated for 06Z TAFs.

&&

.KEY MESSAGES...
1. Isolated showers and thunderstorms possible through tonight,
but the risk of hazardous weather is low.

2. Heat and humidity will build into the middle of the week,
along with daily chances for showers and thunderstorms. There is
an increasing threat of severe thunderstorms and potentially
flash flooding during the middle of the week, namely Tuesday
through Thursday.

&&

.DISCUSSION...
KEY MESSAGE 1...Isolated showers and thunderstorms possible
through tonight, but the risk of hazardous weather is low.

Isolated showers will persist through dawn. No significant
weather expected.

Humid again tonight with lows in the mid 60s to low 70s.


KEY MESSAGE 2...Heat and humidity will build into the middle of
the week, along with daily chances for showers and
thunderstorms. There is an increasing threat of severe
thunderstorms and potentially flash flooding during the middle
of the week, namely Tuesday through Thursday.

Broad upper level ridging returns to the eastern US early this
week, bringing in surface high pressure across the eastern US.
Afternoon highs will creep back into the mid 80s to low 90s for
most areas, about 5 degrees above average for early September.
Dewpoints will also remain in the upper 60s to low 70s. The
hottest day(s) looks to be Tuesday and/or Thursday, when high
temperatures could get into the mid 90s across Delmarva and into
the Philly metro. Resulting heat indices will be well into the
90s to around 100 degrees. We will continue to keep an eye on
the potential for any Heat Advisories.

One other aspect to watch with this ridging pattern is the
potential for thunderstorms to rotate around the periphery of
the ridge and the position of a frontal boundary during the
middle of the week. Guidance maintains a consensus that the
pattern will be supportive of multiple rounds of thunderstorms,
especially during the Tuesday through Thursday time frame.

SPC maintains a Slight Risk (2 of 5) for severe thunderstorms
Tuesday for portions of the area, and a Slight Risk has been
introduced for Wednesday. It should be noted that there have
been some indications in the guidance that Wednesday`s severe
potential will be much more conditional, as a frontal boundary
looks to be draped across our area with potential for easterly
winds and marine influence at the surface. This doesn`t mean
there would be zero severe potential, but adds a further degree
of uncertainty to Wednesday`s setup. Thursday remains
highlighted with 15% probabilities for severe thunderstorms. The
northwest flow pattern that will be in place will be supportive
of all severe threats, including damaging winds, large hail,
and tornadoes. The threat for flash flooding is typically lower
with these patterns, however given multiple days with the
potential for storms and recent heavy rainfalls, at least some
risk for flash flooding will exist.

Long story short, the Tuesday through Thursday period looks
very active with multiple rounds of thunderstorms across the
region, but details still remain unclear. Stay tuned for updates
on these threats over the coming days.

By Friday, current model consensus indicates the frontal
boundary will be pushing into and south of our region with
Canadian high pressure building across the Northeast. This
should favor an end to severe weather and flash flooding
potential. Labor Day weekend is still shaping up to feature nice
weather, with temperatures trending slightly below normal and
lower humidity.

&&

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

Through 12Z...VFR initially, then MVFR and perhaps some IFR
ceilings developing. Scattered showers around the region may
cause very brief visibility reductions, but have carried VCSH
for now. The probability of TS has diminished. Winds 5 kts or
less favoring a southerly directions. Low confidence on ceiling
details.

Tuesday...Any MVFR to IFR ceilings lift to VFR by 14Z.
Scattered thunderstorms developing after 21Z from northeast to
southwest. Have opted to carry VCTS everywhere, with PROB30 for
TSRA visibility restrictions. West to southwest winds 5-10 kts.
Low confidence on timing of TSRA, but probability of TSRA at
all terminals at some point after 22Z is at least 50-60%. High
confidence on prevailing VFR through the daytime hours.

Tuesday night...Scattered SHRA/TSRA prior to 06Z. MVFR/IFR
ceilings developing after 06Z. Variable winds early settling out
of the northeast around 5 kts after 06Z. Low confidence on
timing of restrictions.

Outlook...

Wednesday through Thursday...Restrictions possible in showers
and thunderstorms each day, mainly during the afternoon to
evening hours.

Friday through Saturday...Primarily VFR.

&&

.MARINE...
No prevailing marine hazards expected. South to southwest winds
around 5-15 kts. Seas 1-2 feet. Scattered thunderstorms
developing by evening from north to south along the coast into
the overnight hours. Winds and seas higher in and near any
thunderstorms. There is also potential for hail and waterspouts.

Outlook...

Wednesday through Thursday...No prevailing marine hazards
expected. Chances for thunderstorms each day, mainly in the
afternoon and evening hours.

Friday through Saturday...No marine hazards expected. Aside from
a low chance of a thunderstorm near the Delaware coast on
Friday, fair weather is expected.

Rip Currents...

For Tuesday, south-southwest winds will average around 10 mph.
Breaking wave heights around 1 to 2 feet with a 1 to 2 foot
southeast swell around 7 to 8 seconds. Given these conditions,
have opted to continue with a LOW risk for the development of
dangerous rip currents for both the Jersey Shore and Delaware
Beaches.

For Wednesday, east-northeast winds will average around 10 to
15 mph. Breaking wave heights will vary between 2 to 4 feet for
northern beaches, with 1 to 3 feet for southern beaches. A
south-southeast swell is expected with multiple periods. Given
the strengthening onshore flow and higher breaking wave heights,
have opted to go with a MODERATE risk for dangerous rip
currents for Monmouth, Ocean and Atlantic County Beaches in New
Jersey; while opting for a LOW risk for dangerous rip currents
for Cape May County in New Jersey and Delaware Beaches.

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

&&

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

&&

$$

DISCUSSION...AS
AVIATION...AS
MARINE...JD/AS