Clementon New Jersey Weather Forecast Discussion

891
FXUS61 KPHI 111747
AFDPHI
Area Forecast Discussion
National Weather Service Mount Holly NJ
147 PM EDT Sat Oct 11 2025
.SYNOPSIS...
High pressure will continue to move further offshore today. A
coastal storm will then affect the region tonight through early
next week 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 TONIGHT/...
Latest analysis depicts high pressure east of Cape Cod,
continuing eastward into to the Atlantic. One low pressure is
developing just east of Florida, heading north, while another is
over Lake Huron, heading southeast. Both surface lows are
accompanied by closed upper level lows, with the northern one
being notably stronger at present, with an upper ridge aligned
north-south from just east of Cape Cod southward into the open
Atlantic.
Through the next 24 hours, the two upper level low pressure
systems will continue moving in their respective directions,
but their motion will slow considerably, resulting in the
southern one being near the South Carolina Coast and the
northern one being over Upstate New York in 24 hours. The
surface low for the northern system will wash out as energy
begins to transfer to a new surface low developing off the
Atlantic Coast, while the southern low will head towards the
South Carolina/North Carolina border. The bottom line from all
this is that while the easterly wind will start to increase,
clouds will become more dominant, and the chance of rain will
also be increasing through the next 24 hours, the main show
still looks to be beyond the near-term period, despite a slow
but steady trend towards more unpleasant conditions. Shower
chances during the day today still look relatively low, below 50
percent overall, and while odds do increase during the night
tonight, widespread rain across the entire region still likely
won`t arrive in the next 24 hours, with rain tonight being a bit
more patchy and also concentrated on southern parts of the
forecast region.
The warm advection aloft ahead of these two systems should help
elevate highs a bit today despite the increased cloud cover and
spotty showers, mainly in the mid-upper 60s, with low 70s in the
far south. Lows tonight won`t drop much with the onshore flow,
clouds and increasing rain coverage, with 60s far south, mid-
upper 50s most other areas, except near 50 Poconos and NW NJ.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
***Significant impacts possible from a strong coastal storm
 Sunday through Monday***
Overview: We continue to closely monitor the potentially
significant coastal storm that is expected to develop near the
North Carolina coast along a stalled front beginning today. This
storm is anticipated to strengthen and lift northward Sunday
into early next week. The primary impacts will be from coastal
flooding, beach erosion, dune breaching, strong to potentially
damaging winds, and heavy rain. The heaviest rainfall and
strongest winds are still anticipated to be near the Atlantic
coast.
What has changed: Latest deterministic model guidance has
trended weaker and east with a more elongated low pressure
system compared to previous forecasts. What this means is that
the QPF forecast has been lowered. Even with this current trend,
coastal impacts are still expected to be significant. Also,
with these run to run variations of the deterministic guidance,
it is important to look at the ensembles guidance which does
still have both outcomes of a stronger and more west placement
of the low along with the weaker eastward low. Due to this
spread and uncertainty, not too many changes were made overall
aside from the QPF forecast. Guidance will likely continue to
struggle and vary from run to run with this system until it
actually forms a well defined low pressure center sometime today
or tonight. Our marine hazards were upgraded due to consistent
confidence for gale to storm warning criteria being met. There
is more uncertainty for the High Wind Watch, so that remains
unchanged at this time.
Coastal Storm Forecast Details...
The period Sunday through Monday will be when our area likely
experiences the brunt of the impacts from the coastal storm.
Right now, winds are expected to be sustained at 15-25 mph
inland and 30- 40 mph at the coast. For wind gusts, 30-40 mph
for inland areas with 50-60 mph along the coast. Sunday morning
through Monday is when the strongest winds are expected. Due to
the uncertainty in the intensity and forecast track of the
coastal storm, there were no changes made to the High Wind Watch
with this update as mentioned above. Regardless, power outages
and tree damage are possible, especially toward the coast.
In addition to the wind, heavy rain is forecast, and a MARGINAL
(1/4) Risk Excessive Rainfall Outlook is in place for the
southern half of Delmarva and mainly the coastal areas of New
Jersey for Sunday through Sunday night. A widespread 1-2 inches
of rain is forecast across our entire area, with locally higher
amounts of 2-3 inches possible, especially near the coast. These
totals have lowered compared to previous forecasts due to model
trends. Now, this may seem like a lot of rain, but it is
important to keep in mind that this will be falling over a 48-60
hour period. It has also been quite dry. Given this forecast,
the thinking is that flooding due to heavy rain alone will be
limited to poor drainage and urban areas. However, this rainfall
could exacerbate impacts near the coast with Moderate and
potentially Major coastal flooding ongoing. Significant high
tides are expected due to strong northeast winds resulting in
water piling up along the coast.
The setup is overall very complex. The surface low will be
developing over the Gulf Stream along a stalled boundary, and
its northward movement will depend on how it interacts with a
surface high over Nova Scotia, an upper level low over the Great
Lakes, and even distant Tropical Storm Jerry. The extent and
severity of impacts in our area will be directly related to the
exact track and evolution of the low pressure center. Stay tuned
to the latest briefing packages and forecast updates as the
forecast continues to evolve and details become more apparent
over the next 24 hours.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
The early week coastal storm will be weakening significantly by
Tuesday, but it`s remnant low could still linger in the
vicinity of the coast yielding a chance of showers and somewhat
breezy conditions. The low will eventually weaken and push out
to sea by Tuesday night. Thereafter, broad and relatively weak
high pressure will build across the Great Lakes region. Its
cooler airmass will arrive toward the end of the week, with
below normal temperatures and fair weather anticipated for
Thursday and Friday.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.
Today...MVFR conditions continue with some isolated showers.
Conditions look to improve briefly to VFR this afternoon before
likely degrading back to MVFR late today as more showers and
lower cigs overspread the region well in advance of an
approaching coastal storm. Winds east to northeast 10 kts,
stronger at KACY. Moderate confidence.
Tonight...Rain becomes more predominate by late tonight with
MVFR conditions likely at times. Winds will also increase closer
to 20 kts, higher at KACY. Moderate confidence.
Outlook...
Sunday through Monday...MVFR to IFR conditions expected with
moderate to heavy rain moving through and gusty winds. Northeast
wind gusts near 45 kt possible at KACY. Gusts out of the
northeast around 25-35 kt expected at the I-95 terminals and
KMIV, with 20-30 kt anticipated within the Lehigh Valley.
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..VFR with no significant weather.
&&
.MARINE...
Increasing easterly flow ahead of an approaching coastal storm,
along with building seas, will bring SCA conditions to all
ocean waters by afternoon, so have expanded and extended SCA.
Sub-SCA conditions will remain on the bay during daylight today.
Approaching storm will cause building seas and winds across all
waters tonight and especially beyond, necessitating gale and
storm warnings.
Outlook...
Sunday through Monday...A Storm Warning is in place through
Monday for all marine zones except the upper Delaware Bay where
a Gale Warning has been issued. Northeast winds 35-45 kt and
gusts up to 50- 55 kt expected within the Atlantic coastal
waters and mouth of Delaware Bay. For the Upper Delaware Bay,
winds 25-35 kt with gusts near 45 kts where the Gale Warning is.
Dangerous seas upward of 15 to 20 feet expected. Periods of
moderate to heavy rain and sea spray restricting visibility at
times.
Monday night through Wednesday...Conditions will begin to
improve as the storm weakens and begins to move away. However,
gale force winds may linger through Tuesday and elevated seas
above 5 feet may linger through Wednesday.
&&
.TIDES/COASTAL FLOODING...
Minor coastal flooding is forecast with this morning`s high
tide, mainly for Atlantic, Cape May, and Cumberland Counties in
NJ and Sussex and Kent Counties in DE. As a result, the Coastal
Flood Advisory remains in effect. As water levels will start
building thereafter, continued advisory into early Sunday even
though some areas may not quite reach advisory levels on
tonight`s cycle.
Meanwhile, there is an increasing risk of moderate to major
coastal flooding impacts beginning Sunday through Monday as a
strong 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. Confidence has increased enough
such that we`ve upgraded the Coastal Flood Watch to a Warning
Sunday through Monday.
Severe beach erosion and dune breaching are 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
potentially significant coastal flood event.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Coastal Flood Advisory from 2 PM Sunday to 11 PM EDT Monday
     for PAZ070-071-106.
NJ...Coastal Flood Warning from 11 AM Sunday to 9 PM EDT Monday for
     NJZ016.
     Coastal Flood Advisory until 8 AM EDT Sunday for NJZ021>025.
     Coastal Flood Warning from 8 AM Sunday to 8 PM EDT Monday for
     NJZ012>014-020>027.
     High Wind Watch from Sunday morning through late Sunday night
     for NJZ013-014-020-022>027.
     Coastal Flood Advisory from 2 PM Sunday to 11 PM EDT Monday
     for NJZ017>019.
DE...Coastal Flood Warning from 11 AM Sunday to 9 PM EDT Monday for
     DEZ001.
     Coastal Flood Advisory until 8 AM EDT Sunday for DEZ002>004.
     Coastal Flood Warning from 8 AM Sunday to 8 PM EDT Monday for
     DEZ002>004.
     High Wind Watch from Sunday morning through late Sunday night
     for DEZ003-004.
MD...None.
MARINE...Gale Warning from 6 PM this evening to 8 PM EDT Monday for
     ANZ430.
     Storm Warning from 6 PM this evening to 8 PM EDT Monday for
     ANZ431-450>455.
     Small Craft Advisory until 6 PM EDT this evening for
     ANZ450>455.
&&
$$
SYNOPSIS...Guzzo/RCM
NEAR TERM...RCM
SHORT TERM...Guzzo
LONG TERM...Guzzo
AVIATION...AKL/Guzzo/RCM
MARINE...Guzzo/RCM
TIDES/COASTAL FLOODING...WFO PHI

NWS PHI Office Area Forecast Discussion