583
FXUS61 KPHI 200159
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
959 PM EDT Tue Aug 19 2025

.SYNOPSIS...
High pressure centered over portions of New England will slowly
drift east. An area of low pressure and associated front will
pass through the region Wednesday into Thursday. Hurricane Erin
will move north, making its closest approach on Thursday, but
remain well offshore. High pressure will build in for much of
the weekend, though another cold front will approach by the
beginning of next week.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
Clouds cleared out quite a bit across much of the northern to
central portions of the area, however as moisture increases from
the south and deepens some the clouds will fill in and lower
northward through the overnight.

Some sprinkles and light showers are occuring across far
southeastern New Jersey and into Delmarva. High pressure will
relax across the area tonight, but the onshore flow will
continue. This will bring more moisture to the area overnight
with some showers especially for E/SE parts of the area. Temps
tonight will settle into the low 60s for the N/W counties and
mid/upper 60s elsewhere.

For Wednesday, the increased moisture will remain over the area
while some shortwave energy/weak sfc low will move north of the
area. Hurricane Erin will remain well south of the area. The
system sliding by to the north will pull a warm front into our
area and this will help focus some showers. The highest chances
will be across the N/W areas where the better dynamics will
remain, and an area of convergence may enhance the lift enough
to promote some locally heavier rain. A few thunderstorms cannot
be ruled out mainly in the afternoon. Temps will only top out
in the 70s for north NJ and ern PA while some lower 80s will be
across south NJ and Delmarva. Winds will continue from the East
or Southeast at 10 to 15 mph, strongest at the coast.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
Hurricane Erin makes its closest pass on Thursday, mainly bringing a
plethora of marine and tidal impacts to the region. While the storm
will pass about 350-450 miles south and east of our area, our region
is expected to see gusty winds on the waters and immediate coast,
minor to moderate tidal flooding, high surf, and life threatening
rip currents. Please see the marine and tides section below for more
information.

Wednesday Night starts out with some scattered showers and isolated
thunderstorms lingering over the area as weakening front moves in
from the west. Moisture from Hurricane Erin advects in with the
front in place, as well as an upper level jet streak moving over the
northern third of the area, enhancing lift north of I-78. Seeing a
bit of a signal for a PRE (predecessor rain event), but thinking the
heaviest rates stay to the north of our area as the timing of the
incoming front and trough don`t quite line up for our area. Thinking
it will mainly just be some scattered showers overnight, but cannot
rule out a few heavier downpours north of I-78, where a MRGL risk
(1/4) risk for excessive rain is in place. Shower activity should
gradually wane through the night. Temperatures drop into the upper
50s/low 60s north of Philadelphia with mid to upper 60s elsewhere.

Hurricane Erin passes to the south and east on Thursday. Outside of
the immediate coast, it will be a rather benign day with mostly
cloudy and overcast skies, and a northeast breeze in the upper teens
to low twenties. Will be cloudy and cool with highs only in the low
to mid 70s.

Closer to the coast, winds will be stronger, with gusts upward of 40
MPH possible on the immediate coastline, and 20-30 MPH within the
coastal plain. Also cannot rule out a few light showers and isolated
downpours along the coast, though rainfall amounts will be
negligible. The sea will be quite angry with very rough surf and
life-threatening rip currents, with some beach erosion possible. The
highest tides look to come later Thursday evening, with widespread
minor to moderate flooding likely. More information can be found in
sections below.

For the updated Hurricane Erin forecast, see the National Hurricane
Center`s website at www.nhc.noaa.gov.

Things begin to quiet down on Thursday Night as Hurricane Erin
slowly pulls away. Skies clear out and winds die down overnight.
Should be dry with lows in the mid to upper 50s and low 60s.

Friday actually looks pretty nice outside of rough surf and high
seas. High pressure moves in with mostly sunny skies and
temperatures begin to moderate. Temperatures get into the upper 70s
to low 80s as it will be a nice day to close out the week.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Friday night, high pressure will build into the area as Hurricane
Erin moves farther out to sea over the Northern Atlantic Waters.
Winds along the coast will continue to relax, and skies will be
mostly clear. Low temperatures look to be in the mid 50s for most
locations, with low-mid 60s across coastal regions and the urban
corridor. Saturday should be a pleasant day as well, with high
pressure shifting slowly east and offshore, maintaining influence
over sensible weather. Partly to mostly sunny skies are expected
with highs in the low-mid 80s.

Saturday night into Sunday, the upper pattern will begin to support
a period of more unsettled weather, with an upper low shifting east
over portions of Ontario and Quebec, and a positively tilted trough
axis slowly working its way east into our region. There will be a
chance for showers and a few storms across the region beginning
Saturday night. Temperatures looks to hold fairly steady through
Sunday, with highs in the low-mid 80s and lows in the low-mid 60s.

A cold front will eventually work its way through the area, likely
Sunday night into Monday, but while the area is pre-frontal, shower
and storm chances will remain in place. Once the front clears the
area fully Monday night into Tuesday, dry and pleasant conditions
should return.

&&

.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Tonight...VFR ceilings lower MVFR. Some ceilings may lower to
IFR toward daybreak. Some showers possible, mainly overnight.
East winds 10 knots or less. Low confidence on the timing
details of the lower ceilings.

Wednesday...MVFR/IFR ceilings with some showers. A few isolated
afternoon thunderstorms possible. East to east-southeast winds
near 10 knots. Moderate confidence overall.

Outlook...

Wednesday night...MVFR/IFR conditions likely (60-80%) with
scattered showers around and patchy fog.

Thursday...MVFR/IFR ceilings around through most of the day. Wind
gusts 25-35 kt possible at KACY, 20-25 kt at KMIV, and 20 kt
elsewhere.

Thursday night through Saturday...VFR. No significant weather.

Sunday...Periods of sub-VFR conditions are possible in some
showers and storms.

&&

.MARINE...
No changes to near term marine headlines. SCA flags fly for enhanced
seas with the first swells associated with `Erin` arrive across our
waters. East to Southeast winds steadily increase tonight and
Wednesday. Fair into the evening for the northmen waters then rains
arrive from South to North tonight.

Outlook...

Wednesday night... A Small Craft Advisory is in place across
all ocean zones as 6-10 foot seas are expected. Wind gusts near
25 kt possible late as winds ramp up quickly with Hurricane Erin
beginning to make its closest approach.

Thursday through Thursday night... A Gale Watch is in place for
all ocean zones and the lower Delaware Bay. Sustained gale
force winds are possible (30-50%), especially over the open
waters. Max wind gusts of 40-45 kt expected. Seas 10 to 15 feet.
Lesser winds are expected on the upper Delaware Bay, where a
Small Craft Advisory is in effect.

Friday...A Small Craft Advisory will be needed on the ocean once the
gales end as seas of 6 to 10 feet are expected, and winds near 25
kt.

Friday night through Sunday...Winds are expected to have diminished
below 25 kts by Friday night. However, seas will remain elevated
through Sunday, slowly diminishing. Seas as high as 8 ft Friday
night, decreasing slowly to near 5 feet by Sunday.

Rip Currents...

STAY OUT OF THE WATER!

Through Wednesday, northeast to east-southeast winds 10-20 mph.
A continuation of building seas will lead to breaking waves in
the surf zone increasing into the 5-8 foot range. The conditions
worsen with long period southeasterly swells (15-18 seconds)
associated with Hurricane Erin continuing to arrive. A HIGH
risk for the development of life-threatening rip currents
continues for the Jersey Shore and the Delaware Beaches.

For Thursday, northeast winds 20-30 mph with gusts up to 40 mph.
Dangerous surf zone conditions continue as breaking waves peak
at 7-11 feet along with long period southeasterly swells (15-18
seconds) still associated with Hurricane Erin. A HIGH risk for
the development of life-threatening rip currents continues for
the Jersey Shore and the Delaware Beaches.

A High Surf Advisory is in effect for Wednesday through Thursday
night for the New Jersey and Delaware Atlantic coasts as waves
in the surf zone reach and exceed 8 feet.

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

&&

.TIDES/COASTAL FLOODING...
Prolonged onshore flow will result in periods of tidal flooding
this week. Tidal flooding working up the tidal portion of the
Delaware Bay this evening should be spotty minor.

Water will slowly pile up as onshore flow continues through at
least Thursday. Swells from Hurricane Erin will also enhance
the threat for tidal flooding and push of water onshore,
especially as it gets closer to Wednesday into Thursday.
After a round of mostly sub-advisory minor tidal flooding this
evening, more minor coastal flooding is possible Wednesday.

The potential for a more widespread moderate coastal flood event
as Erin passes Thursday into Friday has increased, so have
issued coastal flood watches for most of the coastal strip at
this time. Uncertainty exists regarding longevity, with some
guidance indicating several cycles could reach moderate, so have
gone a bit long with the timing even though the most confidence
period is late Thursday. Significant coastal flooding is less
likely on the tidal Delaware though advisories may be necessary
here. Even less risk exists along the Chesapeake Bay shoreline.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...Coastal Flood Watch from Thursday afternoon through late
     Friday night for NJZ021.
     Coastal Flood Watch from Thursday afternoon through Friday
     evening for NJZ013-014-020-022>027.
     High Risk for Rip Currents through Thursday evening for NJZ014-
     024>026.
     High Surf Advisory from 6 AM Wednesday to 6 AM EDT Friday for
     NJZ014-024>026.
DE...Coastal Flood Watch from Thursday afternoon through late
     Friday night for DEZ002.
     Coastal Flood Watch from Thursday afternoon through Friday
     evening for DEZ003-004.
     High Risk for Rip Currents through Thursday evening for DEZ004.
     High Surf Advisory from 6 AM Wednesday to 6 AM EDT Friday for
     DEZ004.
MD...None.
MARINE...Small Craft Advisory from 6 AM Thursday to 6 AM EDT Friday for
     ANZ430.
     Gale Watch from Thursday morning through late Thursday night
     for ANZ431-450>455.
     Small Craft Advisory until 6 AM EDT Thursday for ANZ450>455.

&&

$$

SYNOPSIS...Cooper
NEAR TERM...Gorse/OHara
SHORT TERM...Hoeflich
LONG TERM...Cooper
AVIATION...Gorse/Hoeflich/OHara
MARINE...Gorse/Hoeflich/OHara
TIDES/COASTAL FLOODING...PHI