687
FXUS61 KPHI 062033
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
433 PM EDT Sun Jul 6 2025

.SYNOPSIS...
High pressure will retreat offshore today, resulting in
increasing humidity. Bermuda high pressure will then remain in
place through the upcoming week. Chantal`s remnants will pass to
our south late Monday, then a few additional weak systems will
impact the region through the remainder of the week.

&&

.NEAR TERM /THROUGH MONDAY/...
Tonight... We`ll start the period with a some scattered showers
and tstms across the eastern shore of MD and Delaware which
will only last until around sunset before diminishing. These are
the result of the increasing humidity and daytime warmth along
with a minor shortwave moving in from the south. A couple
downpours are possible. We`ll continue with the chance pops for
the period.

It`ll become increasingly humid overnight and temperatures will be
seasonably warm with lows only dropping below 70 degrees across the
far N/W areas. Low clouds will move in towards dawn while some light
fog could develop too. Light S to SE expected.

Monday... The influence of (the remnants of) Chantal arrive
Monday with deeper moisture along with more upper shortwaves and
decent instability. We expect increasing chances for showers
and scattered tstms as the morning progresses and into the
afternoon. Downpours and localized flooding are expected. The
overall coverage of flooding is expected to be small and likely
restricted to Delmarva and perhaps south NJ. There may be a few
high rainfall totals (over 2 inches) but the overall speed of
the system should keep most reports in the 1 to 2 inch range for
the S/E areas. These also could be a few strong gusts too with
isolated severe weather possible. We`ll include the possible
hazards in the next briefing package which will be issued later
today.

The latest fcst has high temps on Monday a degree or two cooler than
yesterday. This along with the higher dew points will keep Apparent
temps just short of Heat Advisory criteria.

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
The overall atmospheric setup for Monday night through Tuesday night
is a continuation of Monday. Coverage of showers and thunderstorms
will be isolated Monday night before coverage picks back up during
the day Tuesday. A cold front will be sinking southward Monday night
but does not actually start to fully move into the area until
Tuesday and stalls out across the southern half of the area by
Tuesday night or Wednesday morning.

During the day Tuesday, the coverage of showers and
thunderstorms increases as the cold front sinking southward
acts as an increasing trigger mechanism to an already conducive
environment for diurnally driven convection. We will be well
into a tropical air mass with temperatures reaching the mid 80s
to mid 90s and dew points will be well into the 70s. This means
heat index values will near 100 degrees for the urban corridor,
southern New Jersey, and Delmarva. A Heat Advisory might be
needed for the urban corridor if the trend continues. This
environment will support growing instability. MLCAPE values are
upwards of 2000-3000 J/kg but shear will be on the lower side.
As a result, the potential is there for isolated severe
thunderstorms with water loaded downdrafts leading to the
primary concern being damaging wind gusts. Our whole area is in
a Marginal (1/5) risk for severe weather for this exact reason.

Another concern is the localized flash flooding threat. Forecast
soundings on Tuesday show a prime heavy rain profile with tall
skinny CAPE, PWAT values of 2-2.3 inches with occasional periods of
2.5 inches, a suitable warm cloud layer depth, and the potential for
training showers and storms that will be sufficient rainfall
producers. Our whole area is in a Marginal (1/4) risk in the
Excessive Rainfall Outlook for the risk of localized flash flooding.

By Tuesday night, the coverage becomes more isolated as the
diurnally driven convection starts to diminish but the cold
front does stall over the southern portion of our area.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
We stay unsettled into the long term with the cold front staying
stalled across the area and multiple disturbances moving through. On
Wednesday, there will be isolated showers and thunderstorms around
but there is the potential for some more scattered coverage near the
stalled front located close to Delmarva and southern New Jersey as
this front might act as a focal point to enhance the daytime
convection. On Thursday and Friday, a weak disturbance looks to move
through which will lead to scattered showers and thunderstorms both
days. Another weak disturbance moves in for Saturday keeping showers
and thunderstorms going.

During the second half of the week and into the beginning of the
weekend, high temperatures will be mainly in the 80s. Dew points
will remain in the 60s and 70s, so we continue to hold onto the
humidity.

&&

.AVIATION /21Z SUNDAY THROUGH FRIDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Rest of Today...VFR. South to southwest and increasing to 5-10
kt. High confidence.

Tonight... VFR much of the night but then IFR or low-end MVFR
CIGS arrive as low level winds turn more onshore. Light fog
possible too. Light S/SE winds. Medium confid overall.

Monday... IFR or low-end MVFR conditions early then mixing out
to VFR 14Z/15Z most spots. Chance of showers/tstms after 16Z
most areas into the afternoon. VCSH and PROB30 used for the
ending periods of the TAFS. South to Southwest winds increasing
to 10 to 15 kts. Medium confid overall.

Outlook...

Monday through Friday...Prevailing VFR with daily chances for
thunderstorms, especially in the afternoon and evening hours.
Areas of fog possible at night.

&&

.MARINE...
Winds and seas will remain below SCA levels tonight and into Monday.
Winds and seas do increase Monday afternoon and come up just short
of SCA levels. We`ll hold on any flag attm. Isolated showers/tstms
into the early evening for Delaware Bay and Delaware Coastal waters
today then more scattered showers/tstms Monday afternoon/evening. As
always, higher winds and seas locally near tstms.

Outlook...

Monday night through Friday...Wind and seas are forecast to
remain below advisory criteria. Daily chances of showers and
thunderstorms, otherwise fair weather.

Rip Currents...

For Monday, southerly winds will increase to 10-15 mph.
Breaking wave heights increase to 2-3 feet with a primary S
swell around 3 feet and a 6-8 second period. Given slightly
stronger winds and slightly higher waves with slightly higher
swell compared to Sunday, kept MODERATE at the more southerly
facing NJ beaches of Cape May, Atlantic and Ocean, and LOW for
the easterly facing beaches of Monmouth and DE.

For Tuesday, winds shift southwesterly and decrease to 5-10
mph. Breaking wave heights remain around 2-3 feet with a
primary S swell increasing to 4 feet at a 6-8 second period.
Given the higher swell, went with a MODERATE rip current risk at
all beaches.

Rip currents occur often in the vicinities of jetties and piers
and the speed of the currents are generally maximized at low
tides.

&&

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

&&

$$

SYNOPSIS...Guzzo/Staarmann
NEAR TERM...OHara
SHORT TERM...Guzzo
LONG TERM...Guzzo
AVIATION...Guzzo/OHara/Staarmann
MARINE...Guzzo/OHara/RCM/Staarmann