243
FXUS61 KPHI 120742
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
342 AM EDT Sun Oct 12 2025

.SYNOPSIS...
A coastal storm will affect the region through Monday bringing
significant impacts to parts of our area. Improving conditions
expected by Tuesday as the storm weakens and moves out to sea.
High pressure will begin building back into the region during
the middle to end of next week.

&&

.NEAR TERM /THROUGH MONDAY/...
***SIGNIFICANT IMPACTS FOR OUR COASTAL COUNTIES FROM A COASTAL
 STORM TODAY THROUGH MONDAY***

As of early this morning, a primary surface low was positioned
off the South Carolina coast. A secondary low was starting to
develop closer to Cape Hatteras, and this low will be the main
impact on our weather thru Monday. This low will strengthen as
it heads northward, eventually stalling just off the Jersey
Shore before starting to weaken and move away Monday night and
beyond. As the pressure gradient tightens on its northwestern
flank, a low level easterly jet will intensify, with winds
likely gusting up to 60 mph near the immediate coast and 50 mph
across interior coastal NJ and DE. Further inland, the jet
dwindles markedly, with only gusts of 30-40 mph in Philly and
even lower further inland. Strongest winds look to spread north
along the coast starting in Delaware late this afternoon and
continuing north to near Sandy Hook by late tonight before they
begin to dwindle towards dawn Monday. Thus, inherited high wind
warnings and wind advisories have been maintained as-is.

Rain-wise, however, the trend continues in the drier direction
for most. This low will be relatively compact, and drier air
will be trying to drain southwestward on its northwest flank, so
heavy rainfall across much of the area now looks like more of a
struggle. The entire area will get SOME rain, but it now looks
more likely that the majority of our region will receive less
than an inch. The exception is along the immediate coastal
counties, where 1-3 inches still looks probable, enhanced by the
strong low-level jet ejecting onto the coast. For coastal areas,
steadiest rain will be later today into tonight, but inland,
wraparound moisture as the low begins to weaken means that
Monday may be the wettest day overall.

Temperature-wise, most areas should be in the 60s again today,
but as cooler air wraps around the system, temps will fall into
the 50s tonight and much of the area will not be able to return
to the 60s on Monday thanks to clouds and lingering rain.

See the marine and coastal flood sections below for more details
on those hazards from this system.

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
We continue to deal with our coastal storm Monday night but it does
start to weaken and this trend continues into Tuesday. As this low
weakens, it also starts to move away from our area. Some model
guidance shows the potential still for a secondary low
developing to the south of our initial low. The bottom line is
that we continue to deal with rain Monday night into Tuesday
morning with the higher PoPs closer to the coast with lower PoPs
as you head west. By Tuesday afternoon, we are much drier with
just a lingering shower possible for the coastal areas.

Winds do stay elevated Monday night and Tuesday as the coastal storm
is still near and we continue to have a tight pressure gradient. On
Monday night, gusts of 20-30 for inland areas and 30-40 mph still
for the coastal zones. For Tuesday, wind gusts are 15-20 mph for
most of the inland areas with 20-30 mph gusts near the coast.

Our coastal storm pushes more out to sea by Tuesday night. We are
dry Tuesday night with clouds decreasing. Wind gusts remain at
around 15-20 mph inland and 20-30 mph near the coast due to the
tight pressure gradient remaining.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
A broad area of high pressure builds in across the Great Lakes
region by midweek and sinks southeast a bit closer to our area by
the end of the week. This high pressure system becoming our dominant
weather feature leads to minimal cloud cover and a stretch of dry
conditions. Wednesday is a bit more mild compared to Thursday and
Friday as cold air advection becomes more dominant for the end of
the week with below normal temperatures anticipated. Temperatures
may begin to moderate on Saturday.

&&

.AVIATION /07Z SUNDAY THROUGH THURSDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Thru 12Z...MVFR ceilings, however times of VFR ceilings at some
terminals. Some spotty showers will result in visibility
restrictions at times. Northeast winds 10-15 knots with gusts
to 20-25 knots late (highest toward the coast, slower increase
at KABE and KRDG). Low confidence regarding ceiling height and
visibility timing/details.

Today through Monday...MVFR/IFR conditions with rounds of rain
moving through, with the most widespread rain looking to occur
mostly tonight into Monday. Northeast winds 15-25 knots with
gusts 25-40 knots, highest at KACY and KMIV. Low confidence on
timing details, especially with visibility restrictions.

Outlook...

Monday Night...Restrictions expected with showers and low clouds.
Wind gusts diminish to around 15-25 kt out of the north/northeast.

Tuesday...Conditons improve but sub-VFR conditions possible with
lingering showers and clouds. Wind gusts could get near 20 kt at
times.

Wednesday and Thursday..VFR with no significant weather.

&&

.MARINE...
No changes made at this point to the marine hazards. East to
northeast winds and waves are increasing early this morning and
this will continue through today. The strongest winds are
expected during late this afternoon and evening before
gradually subsiding overnight. Still expecting storm force
winds on the lower Delaware Bay and the NJ/DE Atlantic coastal
waters. For the upper Delaware Bay, expect gale conditions.

Dangerous seas up to 20 feet are expected. Periods of rain and
sea spray restricting visibility at times, especially this
afternoon into Monday.

Outlook...

Monday night through Thursday...Conditions will begin to improve as
the storm weakens and begins to move away. However, near gale force
winds may linger through Tuesday and seas remain near 10-12 feet. On
Wednesday and Thursday, SCA winds and elevated seas above 5 feet
look to continue.

&&

.TIDES/COASTAL FLOODING...
Coastal Flood Advisories continue for the tide cycle early this
morning before the larger event later today. The latest numbers
for the upcoming tide were similar to previous fcst, so saw no
need for any major changes. Either low-end minor tidal flooding
or just below that is expected early this morning.

Meanwhile, there is an increasing risk of moderate to major
coastal flooding impacts beginning today through Monday as a
coastal storm impacts the region. Guidance still varies in
potential outcomes of this storm with regard to severity of
coastal flood impacts locally, however we remain very concerned
about the potential for significant impacts from this storm
along our coasts. At this time, the greatest threat of impacts
are anticipated to occur along the Atlantic coasts of New Jersey
and Delaware, and Delaware Bay. A Coastal Flood Warning remains
in effect for Sunday through Monday.

Severe beach erosion and dune breaching are quite possible
along the entire New Jersey Shore and for Delaware Beaches due
to the very high surf conditions that are expected. Interests
along the Atlantic coast, Delaware Bay, back bays, and tidal
waterways should remain alert for forecast updates regarding
this significant coastal flood event.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Coastal Flood Advisory from 2 PM this afternoon to 11 PM EDT
     Monday for PAZ070-071-106.
NJ...Coastal Flood Warning from 11 AM this morning to 9 PM EDT
     Monday for NJZ016.
     Coastal Flood Advisory until 8 AM EDT this morning for
     NJZ021>025.
     Coastal Flood Warning from 8 AM this morning to 8 PM EDT
     Monday for NJZ012>014-020>027.
     Wind Advisory from 11 AM this morning to 6 AM EDT Monday for
     NJZ013-020-022-027.
     High Wind Warning from 11 AM this morning to 6 AM EDT Monday
     for NJZ014-023>026.
     Coastal Flood Advisory from 2 PM this afternoon to 11 PM EDT
     Monday for NJZ017>019.
DE...Coastal Flood Warning from 11 AM this morning to 9 PM EDT
     Monday for DEZ001.
     Coastal Flood Advisory until 8 AM EDT this morning for
     DEZ002>004.
     Coastal Flood Warning from 8 AM this morning to 8 PM EDT
     Monday for DEZ002>004.
     Wind Advisory from 11 AM this morning to 6 AM EDT Monday for
     DEZ003.
     High Wind Warning from 11 AM this morning to 6 AM EDT Monday
     for DEZ004.
MD...None.
MARINE...Gale Warning until 8 PM EDT Monday for ANZ430.
     Storm Warning until 8 PM EDT Monday for ANZ431-450>455.

&&

$$

SYNOPSIS...Guzzo/RCM
NEAR TERM...RCM
SHORT TERM...Guzzo
LONG TERM...Guzzo
AVIATION...Guzzo/RCM
MARINE...Guzzo/RCM
TIDES/COASTAL FLOODING...