085
FXUS61 KPHI 091110
AFDPHI

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

.WHAT HAS CHANGED...
No significant changes to the forecast.

&&

.KEY MESSAGES...
1. Today still looks to be largely dry, but cannot completely
rule out an isolated shower or storm this afternoon. Daily
chances for showers and thunderstorms will return Monday and
into the middle of the week. There is a risk for strong to
severe thunderstorms during the week, as well as a marginal
risk for localized heavy rainfall leading to flash flooding.

2. Hot and humid conditions will persist into the middle of the
week, but humidity will not be as oppressive as recent days.

&&

.DISCUSSION...
KEY MESSAGE 1...Today still looks to be largely dry, but cannot
completely rule out an isolated shower or storm this afternoon.
Daily chances for showers and thunderstorms will return Monday
and into the middle of the week. There is a risk for strong to
severe thunderstorms during the week, as well as a marginal risk
for localized heavy rainfall leading to flash flooding.

A weak cold frontal passage early this morning will usher in
slightly drier air. This combined with subtle subsidence and
rising heights aloft will limit convection potential today.
However, we cannot completely rule out some isolated convection
popping up in the afternoon, especially along the sea and/or
bay bay breezes. These will act as surface forcing mechanisms
where the westerly surface winds inland meet the southerly
surface winds over the marine areas. If anything does develop,
it`ll be battling several limiting factors such as dry air aloft
and subsidence, and will be short lived as shear is generally
less than 20 kts. DCAPE and low level lapse rates are high
though, so any stronger storms could produce brief strong wind
gusts and frequent lightning. Convective potential will end by
sunset.

A mid level shortwave trough will approach the area by late
Monday as mean flow shifts more westerly and mid level flow
increases amid falling heights. The timing of this has trended
a bit faster and farther east with recent guidance, which has
increased our chances for thunderstorms on Monday. SPC has
expanded the Marginal Risk into much of our forecast area, and
if recent trends hold, would not be surprised to see the Slight
Risk across the Ohio Valley expanded farther east into our
area for Monday. The main threat with any thunderstorms, which
the extended range of the CAMs and shear profiles suggest will
organize into a line of sorts, will be damaging winds. However,
could also see a non-zero tornado threat as well depending on
how low low shear and thermodynamics evolve. If a line of storms
does materialize, the threat of flash flooding will be quite
limited due to the speed of the convection with the faster mid
level flow. Details are still a little unclear, but the threat
of storms and severe storms is increasing for Monday.

Recent forecast trends have resulted in lower instability
compared to previous runs on Tuesday given the faster evolution
of the synoptic features (cold front and shortwave trough).
Essentially, it looks like Tuesday`s activity will be shunted to
our southwest compared to previous forecasts based on the latest
synoptic trends. With that said, we could still see some
convection potential or even get the remnants of whatever
occurs upstream later in the evening. So while the threat of
severe storms now appears to be lessening for Tuesday, we could
still get showers and storms in some form. Details for Tuesday
are even more uncertain than Monday, and Monday`s activity will
probably play some role in what exactly happens Tuesday.

Behind the cold front that looks to come through Tuesday into
Wednesday, which will help break the excessive heat and humidity
some, the pattern aloft will still support diurnally driven
convection at least through Thursday. A much drier and cooler
airmass will arrive by Friday and Saturday, which will bring us
a more pronounced break in convective potential and more
pleasant weather conditions.


KEY MESSAGE 2...Hot and humid conditions will persist into the
middle of the week, but humidity will not be as oppressive as
recent days.

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 the week as Bermuda high
pressure persists offshore. This will keep a very warm and
moist airmass in place across the region through the period.

Hot and humid conditions will continue for the next several
days. A weak cold frontal passage early this morning will usher
in slightly drier air and allow dewpoints to mix out some
during the afternoon hours both today and Monday. This will give
some slight reprieve from the excessive humidity we`ve
experienced in recent days, though highs will still be in the
upper 80s to low or even mid 90s. The lower dewpoints will
result in maximum heat indices mainly in the mid to upper 90s,
though could get near 100 degrees in Delmarva and near the coast
in New Jersey. Since the forecast is decidedly below criteria,
we have opted to continue without a new Heat Advisory, though
it will still be hot and humid.

The faster synoptic pattern evolution described in the first
section above has resulted in a slightly lower forecast for
temperatures and heat index values for Tuesday. High
temperatures in the mid 80s to low 90s for most, and heat index
values are now forecast to peak below Heat Advisory criteria.
Once the cold front fully comes through, we will see a continued
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.

By Friday and Saturday, a much drier and cooler airmass will
arrive, which will bring much more pleasant weather conditions.
Dewpoints may drop into the 50s again for many areas with highs
forecast to be in the low to mid 80s.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Today...VFR expected. An isolated shower or storm in possible,
especially near the sea and/or bay breeze potentially impacting
ACY/MIV/ILG, but probability is too low to include a TAF mention.
Westerly winds increasing to near 10 kts. High confidence in
prevailing VFR.

Tonight...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 tonight. 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 today...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/Guzzo/Staarmann
AVIATION...Staarmann
MARINE...DeSilva/Staarmann