831
FXUS61 KPHI 210736
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
336 AM EDT Thu Aug 21 2025

.SYNOPSIS...
Hurricane Erin will make its closest pass to the Mid Atlantic
through today, bringing significant coastal and marine hazards
to the region. Erin will push farther out to sea tonight into
Friday as weak high pressure will builds into the area, with
fair weather expected through Saturday. A cold front will
approach the region on Sunday, then move offshore by Monday,
bringing more unsettled conditions. Cooler and drier high
pressure will then build into the region into the middle of next
week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Hurricane Erin will bring significant coastal hazards to the
New Jersey and Delaware coastlines through tonight. While the
closest point of approach of Erin will be ~300-400 miles
southeast of our area, the wind field of Erin will continue to
grow in size with Tropical Storm force winds reaching just off
our coasts. The main impacts from Erin will be strong gusty
winds, life threatening rip currents, strong powerful seas
yielding beach erosion, and coastal flooding. Refer to the
Marine and Coastal Flooding sections below for further details.

Outside of coastal areas, overcast skies, breezy northeast
winds, but dry conditions are expected today. Sustained winds
around 10-15 mph are anticipated where winds may occasionally
gust upwards of 25- 35 mph. With the cloudy and breezy
conditions, high temps will remain below normal with highs only
in the upper 60s to low 70s.

For coastal areas, a much different day is anticipated as
northeast winds will be much stronger with sustained winds of
25-35 mph where gusts upwards of 50 mph are possible along the
immediate coast. No changes have been made to the Wind Advisory,
which begins at 10 AM this morning until midnight tonight from
Ocean County southward. Monmouth County should fall short of
advisory criteria due to shorter fetch off the Atlantic. A few
showers from the outer bands of Erin may reach our coastline,
but nothing of significance in terms of precipitation is
expected while under overcast skies. The more concerning threat
to coastal locales will be the aforementioned threat of powerful
seas causing beach erosion, rip currents, and tidal/coastal
flooding, where further details can be found in their respective
sections below.

Conditions will begin to improve for all areas tonight as Erin
begins to accelerate northeast away from the area. Skies will
begin to scatter out after sunset from west to east, giving way
to clear skies after midnight. Gusty winds may linger into the
early evening, but overall will diminish as the night
progresses. Low temps will fall into the low 50s to low 60s.

For the latest updates on Hurricane Erin, please proceed to the
National Hurricane Center`s website: www.nhc.noaa.gov.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As Hurricane Erin pushes well away from our are into Friday,
weak ridging will build across the region. This will give us a
nice break from the active and lousy weather conditions we`ve
experienced much of this week. Temperatures will return toward
normal values, with forecast high temperatures in the mid 80s
and lows in the mid 50s to mid 60s for most areas.

Friday will see pleasantly dry air thanks to dewpoints mixing
out into the 50s and even some upper 40s under a light northerly
breeze. Friday night into Saturday morning will feature below
normal temperatures in the mid 50s to low 60s in many areas. As
surface high pressure shifts offshore into Saturday, surface
flow will turn southerly, which will begin to increase
temperatures and dewpoints a few degrees compared to Friday, but
still a very pleasant late August day. The dry air and ridging
will result in mostly sunny/clear skies through Saturday as
well.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Another pattern change on the horizon beginning Sunday through
Monday as rather amplified upper troughing develops across the
Great Lakes and Midwest region. This troughing pattern will be
unusually strong for late August standards. More humid and
showery/storm conditions can be expected Sunday through Monday
before a cold front arrives sometime Monday, ushering in a
cooler and much drier airmass in its wake into the middle of
next week.

The synoptic pattern will be favorable for widespread
convection Sunday through Sunday night, with some activity
likely lingering into Monday as well. The exact details of this
convection remain unclear at the moment, but this is not a
particularly favorable setup for severe storms or flash
flooding. We`ll continue to monitor any potential threats from
these showers and storms in the coming days though. Temperatures
will remain near to slightly below normal with highs in the
upper 70s to mid 80s Sunday and Monday and lows in the 60s
Sunday night. Following frontal passage on Monday, cooler and
much drier air will follow into the middle of the week with very
pleasant weather conditions expected. Highs will be mainly in
the 70s, lows mainly in the 50s, and dewpoints in the 40s and
50s. Not bad for late August, with conditions more typical of
mid to late September.

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Through 12Z...IFR ceilings should prevail at all terminals with
occasional instances of LIFR possible at KACY. Isolated showers
and mist possible, only included in TAFs where confidence is
greatest. Northeast winds increase to around 10-15 kt with
occasional gusts up to 20-25 kt. Moderate confidence.

Thursday...Anticipate IFR ceilings to persist through about
18Z, before gradually improving to MVFR thereafter. Skies may
begin to scatter out at KRDG/KABE after 21Z. Northeast winds to
peak around 15-20 kt sustained. Gusts upwards of 20-25 kt at
KRDG/KABE, upwards of 25-30 kt at KTTN/KPNE/KPHL/KILG and
upwards of 30-35 kt at KMIV/KACY. Moderate confidence.

Thursday night...Lingering MVFR ceilings early, improving to
VFR and at all terminals after 03Z (may linger as late as 06Z at
KACY). North winds around 7-12 kt with a few gusts early in the
evening around 20 kt. Moderate-high confidence.

Outlook...

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

Sunday through Monday...VFR conditions should generally
prevail, however scattered showers and thunderstorms are
forecast through this period.

&&

.MARINE...
Tropical Storm Warnings are in effect for the waters offshore
Manasquan Inlet to Fenwick Island through tonight with a Gale
Warning in effect for the waters offshore Sandy Hook to
Manasquan Inlet through tonight. For the lower Delaware Bay, a
Gale Warning is in effect through midnight tonight. For the
upper Delaware Bay, a Small Craft Advisory is in effect through
tonight.

Northeast winds continue to steadily increase today as
Hurricane Erin approaches with sustained winds between 25-35 kt
expected. Wind gusts upwards of 40-45 kt are expected on the
Atlantic coastal waters with gusts upwards of 30-40 kt expected
on the Delaware Bay before gradually diminishing overnight.
Occasional showers possible across all waters which may cause
locally higher gusts.

Seas of 8-12 feet this morning will steadily build up to 12-17
feet this afternoon before gradually beginning to abate tonight
for the Atlantic coastal waters. Rough and choppy waters are
expected on the Delaware Bay.

Outlook...

Friday through Saturday night...Small Craft Advisory conditions
expected, mainly due to elevated seas from departing Hurricane
Erin.

Sunday through Monday...Conditions should remain below advisory
criteria, however scattered showers and thunderstorms are
forecast.

Rip Currents...

STAY OUT OF THE WATER!

For today, northeast winds 25-35 mph with gusts up to 50 mph.
Dangerous surf zone conditions continue as breaking waves peak
at 7-12 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.

For Friday, conditions begin to improve but still expecting
high waves of 5 to 9 feet and a long period 13 to 16 second
swell with Hurricane Erin pulling away. A HIGH risk for
development of life-threatening rip currents will remain through
the end of the week.

A HIGH risk of rip currents is likely to persist through
Saturday, and possibly Sunday as well.

A High Surf Advisory and High Risk for Rip Currents statement
are in effect through Friday for the New Jersey and Delaware
Atlantic coasts. Waves in the surf zone will reach and exceed 8
feet, and a high risk of rip currents will persist through the
end of the week.

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

&&

.TIDES/COASTAL FLOODING...
Prolonged and strengthening onshore flow will result in periods
of coastal flooding through the end of this week. 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
on Thursday when the most significant and widespread coastal
flooding impacts are expected. For this evening`s high tide,
minor flooding is forecast along the coasts of Sussex and Kent
Counties in DE and Cape May County in NJ. Spotty minor flooding
is anticipated elsewhere along the ocean coastline and within
the New Jersey side of the Delaware Bay.

A widespread impactful coastal flood event is expected as Erin
passes by Thursday into Friday. The Coastal Flood Watches were
upgraded to Coastal Flood Warnings for all counties along the
Atlantic Ocean and within Delaware Bay as confidence has
increased in widespread moderate flooding occurring across the
coast. There is potential for locally MAJOR coastal flooding
impacts, especially in Sussex County, DE, where we are now
forecasting water levels to reach MAJOR flood stage (8.0 feet
MLLW) at Lewes. The greatest inundation and impacts can be
expected with the Thursday evening high tide. Widespread minor
flooding is forecast with the Friday morning high tide, then
additional moderate coastal flooding is possible with the Friday
evening high tide.

Along the tidal Delaware River, widespread minor flooding is
expected, beginning with tomorrow night`s high tide and
continuing through the high tide late Friday Night/early
Saturday morning. A Coastal Flood Advisory was issued for
communities along the tidal Delaware River, beginning tomorrow
night and continuing through Saturday morning.

Currently, no widespread coastal flooding is forecast for our
Chesapeake Bay shoreline until Saturday morning`s high tide,
though confidence is low on exactly how widespread the tidal
flooding will be.

&&

.CLIMATE...
Near record breaking coldest high temperatures are forecast for
today. Records for our climate sites are listed below:

Record Coldest High Temperatures
                        August 21
Site                  Record/Year
Allentown (ABE)           61/2007
AC Airport (ACY)          66/1956
AC Marina (55N)           67/1956
Georgetown (GED)          69/1990
Mount Pocono (MPO)        54/2007
Philadelphia (PHL)        64/2007
Reading (RDG)             60/1990
Trenton (TTN)             63/2007
Wilmington (ILG)          65/2007

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Coastal Flood Advisory from 11 PM this evening to 5 AM EDT
     Saturday for PAZ070-071-106.
NJ...Coastal Flood Advisory from 9 PM this evening to 2 AM EDT
     Saturday for NJZ016.
     Coastal Flood Warning until 2 AM EDT Saturday for NJZ023-024.
     High Risk for Rip Currents through Friday afternoon for NJZ014-
     024>026.
     High Surf Advisory until 6 PM EDT Friday for NJZ014-024>026.
     Wind Advisory from 10 AM this morning to midnight EDT tonight
     for NJZ024>026.
     Coastal Flood Warning from 5 PM this afternoon to 2 AM EDT
     Saturday for NJZ012>014-020>022-025>027.
     Coastal Flood Advisory from 11 PM this evening to 5 AM EDT
     Saturday for NJZ017>019.
DE...Coastal Flood Advisory from 9 PM this evening to 2 AM EDT
     Saturday for DEZ001.
     Coastal Flood Warning until 2 AM EDT Saturday for DEZ002>004.
     High Risk for Rip Currents through Friday afternoon for DEZ004.
     High Surf Advisory until 6 PM EDT Friday for DEZ004.
     Wind Advisory from 10 AM this morning to midnight EDT tonight
     for DEZ004.
MD...None.
MARINE...Small Craft Advisory until 6 AM EDT Friday for ANZ430.
     Gale Warning until midnight EDT tonight for ANZ431.
     Small Craft Advisory until 6 AM EDT early this morning for
     ANZ450>455.
     Gale Warning until 6 AM EDT Friday for ANZ450.
     Tropical Storm Warning for ANZ451>455.
&&

$$

SYNOPSIS...Staarmann
NEAR TERM...DeSilva
SHORT TERM...Staarmann
LONG TERM...Staarmann
AVIATION...DeSilva/Staarmann
MARINE...DeSilva/Hoeflich/Staarmann
TIDES/COASTAL FLOODING...Hoeflich/Staarmann
CLIMATE...Staarmann