714
FXUS61 KPHI 090533
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
133 AM EDT Sun Aug 9 2026

.WHAT HAS CHANGED...
Updated Aviation Section for 06Z TAFs.

&&

.KEY MESSAGES...
1. Hot and humid conditions are expected to persist through
Tuesday of next week, though an improvement in humidity is
expected Sunday into Monday.

2. Sunday still looks to be largely dry, then daily chances for
showers and thunderstorms will return Monday and into the
middle of next week. There is a risk for strong to severe
thunderstorms as well as a marginal risk for localized heavy
rainfall leading to flash flooding.

&&

.DISCUSSION...
KEY MESSAGE 1...Hot and humid conditions are expected to
persist through Tuesday of next week, though an improvement in
humidity is expected Sunday into Monday.

A relatively stagnant synoptic pattern will remain in place
across our region. Quasi zonal mid and upper level flow will be
in place through the middle of next week as Bermuda high
pressure persists offshore. This will keep a steady stream of
very warm and moist air in place across the region through the
period.

A prolonged period of hot and humid conditions will continue
for the next several days. A weak cold frontal passage Sunday
will help usher in slightly drier air and allow dewpoints to mix
out during the afternoon hours both Sunday and Monday. This
will give some slight reprieve from the excessive humidity,
though highs will still be in the upper 80s to low or even mid
90s. The lower dewpoints on Monday will result in maximum heat
indices mainly in the mid to upper 90s, though could get near
100 degrees in Delmarva. Since the forecast is decidedly below
Heat Advisory criteria, we`ve opted not to extend it to cover
additional days at this time, though it will still be hot and
humid.

From this forecast update, there remains some moisture
advection ahead of the cold front. However, the cold front
timing looks a bit earlier Tuesday which has resulted in some
lower temperatures and heat index values. Temperatures into the
mid 80s to low 90s for many and heat index values peaking near
or in the 90s for many. Once the cold front fully comes through,
we will see a continued slight reduction in temperatures into
Wednesday and Thursday. Highs by Wednesday and Thursday are
mostly in the mid to upper 80s, which will be closer to average
for early to mid August.


KEY MESSAGE 2...Sunday still looks to be largely dry, then
daily chances for showers and thunderstorms will return Monday
and into the middle of next week. There is a risk for strong to
severe thunderstorms as well as a marginal risk for localized
heavy rainfall leading to flash flooding.

Weather should remain mostly tranquil overnight with some areas
of patchy fog possible, though cannot completely rule out an
isolated shower/storm popping up.

We look to have a weak cold frontal passage early Sunday,
ushering in slightly drier air. This combined with subtle
subsidence aloft will help briefly limit convection potential on
Sunday, though cannot completely rule out some isolated sea
breeze convection in the afternoon.

Better support for forcing aloft will return by late Monday as
mean flow shifts more westerly and mid level flow increases. At
this point though, it appears the greater threat of storms will
be to our west on Monday where SPC has a Marginal Risk
highlighted. Still could get some isolated storms, but Monday is
trending drier locally as the lingering lower dewpoints should
limit our instability a bit.

Recent forecast trends have resulted in lower instability
compared to previous model runs on Tuesday given the timing of
the cold front to be earlier. There does remain uncertainty
around the specific timing details of the front at this time.
However, with that said, there is still better storm chances on
Tuesday compared to Monday. With the stronger mid level flow
aloft, severe thunderstorms still look to be a greater threat
compared to flash flooding, but these details continue to remain
unclear.

Behind the somewhat stronger cold front that looks to come
through Tuesday into Wednesday, which will help break the
excessive heat and humidity some, the pattern aloft may still
support diurnally driven convection.

&&

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

Through 12Z...VFR expected, though some patchy fog may develop
especially for terminals which received rainfall on Sunday
afternoon. Southwest winds generally 5 kts or less. High
confidence, but low confidence on any fog developing.

Sunday...VFR expected. An isolated shower or storm in possible,
especially near the sea and/or bay breeze potentially impacting
ACY/MIV/ILG. Westerly winds increasing to near 10 kts. High
confidence.

Sunday night...VFR. Winds becoming light and variable to calm.
High confidence.

Outlook...

Monday-Thursday...Prevailing VFR, except restrictions possible
with afternoon/evening showers and thunderstorms.

&&

.MARINE...
No prevailing marine hazards through Sunday. An isolated
shower/storm possible along the sea and/or bay breeze, which
could briefly impact the back bays or nearshore waters. South to
southwest winds generally around 10-20 kt with seas around 2-4
feet. Aside from the isolated shower/storm potential, fair
weather expected.

Outlook...

Monday through Thursday...No prevailing marine hazards
expected. Thunderstorms possible each afternoon and evening.

Rip Currents...

For Sunday...Southwest winds will prevail around 10 to 15 mph.
Breaking wave heights generally around 1 to 2 feet, with some
localized beaches up to 3 feet as well as a southerly 2 to 3
foot swell with a period around 6 to 8 seconds. Given these
conditions, have opted to go with a LOW risk for the development
of dangerous rip currents at both the Jersey Shore and Delaware
Beaches.

For Monday...South-southwest winds will be around 5 to 10 mph
in the morning, increasing to around 10 to 20 mph in the
afternoon. Breaking wave heights will generally range between 1
to 2 feet, with multiple swell groups and periods. Given these
conditions, have opted to go with a LOW risk for the development
of dangerous rip currents at all 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...AKL/DeSilva/Guzzo/Staarmann
AVIATION...Staarmann
MARINE...DeSilva/Staarmann