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433
FXUS61 KPHI 121804
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
204 PM EDT Sat Jul 12 2025

.SYNOPSIS...
A very warm and humid airmass will persist over the region into
next week. Several disturbances will move through the area over
the course of the week, generating scattered showers and
occasional thunderstorms, especially in the afternoon and
evening. A cold front is on pace to cross through Monday night
into Tuesday, with high pressure becoming more dominant toward
the middle of the week.

&&

.NEAR TERM /THROUGH SUNDAY/...
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Another round of diurnally driven convection is possible into
the early evening. The best low level convergence and synoptic
scale lift is west of our region over central PA, MD and VA. So
the highest chances for our region will be west of the fall
line. Storm motions, like yesterday, are expected to be very
slow, resulting in a marginal (1 out of 4) risk for localized
flash flooding.

Tonight will be similar conditions to the last two nights, with
continued onshore flow, resulting in another round of low
clouds. Fog will be possible at the coast, but for the most part
this looks like more of a low cloud set up than a fog set up.

As the main trough inches closer to our area on Sunday, chances
for showers and thunderstorms will increase slightly. For the
most part, though the day, it appears as if convection will stay
west of our region.
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&&

.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
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An upper level trough will be moving into the Great Lakes,
allowing stronger southwesterly flow to overspread into the Mid-
Atlantic and Northeast regions. Although the best forcing will
be displaced to our north and west, the atmosphere should
destabilize sufficiently with the mild temperatures and high
moisture content in place. SPC maintains the MARGINAL risk for
severe weather on Sunday over our western most counties, where
best atmospheric parameters overlap with the better forcing.
Outside of the MARGINAL risk, more in the way of garden variety
storms are possible, although most areas near and especially
east of the I-95 urban corridor and towards the coast should
remain dry into the evening. Highs will mainly be in the mid to
upper 80s with heat indicies in the low to mid 90s. Convection
should taper off once again rather quickly with the loss of
diurnal heating into Sunday night, however a few showers or
pockets of heavy rain may make the trek into eastern
Pennsylvania. Another mild and muggy night is expected with lows
similar to those on Saturday night.

On Monday, the upper trough will move into the Eastern US but
will be weakening as it approaches. Although, the atmospheric
forcing will be closer to our area, the upper level support will
not be as strong as it will be on Sunday. This should keep the
overall nature of the potential for severe weather at bay.
However, with strong destabilization and some better forcing,
shower and thunderstorm activity will be more widespread
compared to Sunday, with PoPs in the 50-80% range. Although,
the severe weather potential does not appear to be significant,
we can`t rule out a few strong to severe storms in the afternoon
into the evening hours with the cold front tracking across the
area late Monday night. Locally heavy rainfall will be possible.
Highs will mainly be in the 80s with lows in the 60s/70s.
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&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
For the long term period, there is quite a bit of uncertainty
with the evolution of the pattern. The cold front that tracks
through on Monday night will slow down and virtually stall over
or just south of the region on Tuesday while washing out. With
remaining surface convergence nearby, this may cause another
round of isolated showers and thunderstorms to occur on Tuesday
and/or Wednesday. By mid week, it does seem that Canadian high
pressure will try to take control over the Northeast while
building into the Mid-Atlantic, suppressing any widespread shower
and thunderstorm activity further south. However, considering
it is mid-July after all and the airmass really doesn`t change
all that much in wake of the dying front, occasional rounds of
convective showers and storms are possible each afternoon.
Another trough and frontal boundary appear to approach later in
the week, especially by Friday. Long story short, we should see
lower coverage of convection Tuesday and Wednesday, then
increasing Thursday and especially Friday. Temperatures are
expected to be slightly above normal with highs in the upper 80s
to low 90s daily, where heat indicies may reach close to or top
100 in some spots.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
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The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Through 00Z...Primarily VFR, though may see occasional MVFR
ceilings with lower clouds. For the most part, it appears that
the storms should stay west of the TAF sites. However, think
storm activity could get close to KABE as it is dissipating, so
have a mention of VCTS close to 00Z.

Tonight...Most places should start VFR, but expect low clouds to
develop once again, generally centered within a few hours of
06Z. The set up looks more favorable for low clouds than fog,
except near the coast, including KACY, where both the lowest
ceilings and lowest visibility are likely to occur. By 09Z,
expect most locations to have IFR conditions. Winds remain light
(5kt or less), generally favoring the southeasterly direction,
but could be variable at times.

Sunday...Once low clouds and fog dissipate, which should be by
15Z for most locations, but may linger through 18Z for KACY,
will see a return to VFR conditions. There is a chance for
storms to approach the TAF sites late in the day (near or after
21Z).

Outlook...

Sunday Night through Wednesday...Overall, VFR conditions.
However, afternoon and evening SHRA/TSRA may result in brief
periods of sub- VFR conditions daily. Sub-VFR conditions are
also possible overnight due to low clouds and fog, but
uncertainty remains on this potential, so confidence is low.
-- End Changed Discussion --

&&

.MARINE...
Winds and seas should stay below Small Craft Advisory criteria
through tonight.

Outlook...

Sunday through Wednesday...No marine headlines expected. Winds
generally remain less than 15 kt with seas around 2-3 feet.
Showers and thunderstorms are possible daily, primarily in the
afternoon and evening hours, with the greatest probability of
showers and storms being on Monday.

Rip Currents...

Today, there will be an increasing easterly flow first at 5 to
10 mph, increasing to 10 to 15 mph in the afternoon. Breaking
waves will be as high as 2 to 3 feet. This along with a medium
period southeast swell will result in a MODERATE risk for the
development of dangerous and life threatening rip currents at
the Jersey Shore, and a LOW risk for the development of
dangerous rip currents at Delaware Beaches.

On Sunday, winds will be out of the southeast at around 10 mph
with breaking waves around 1 to 2 feet. This combined with a
lower southeast swell and lower wave heights results in a LOW
risk for the development of dangerous and life threatening rip
currents at the Jersey Shore and at Delaware Beaches.

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

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

&&

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

&&

$$

SYNOPSIS...DeSilva/RCM/Staarmann
NEAR TERM...Johnson
SHORT TERM...DeSilva/Staarmann
LONG TERM...DeSilva/Staarmann
AVIATION...Johnson
MARINE...Johnson/Staarmann