349
FXUS61 KPHI 101019
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
619 AM EDT Fri Oct 10 2025

.SYNOPSIS...
High pressure will shift offshore today into Saturday. A
coastal storm with significant impacts is expected to affect the
region by Sunday and into early next week. 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/...
The chilliest morning of the season is ongoing as temperatures
have fallen into the upper 20s to upper 30s outside of the
immediate urban corridor, Delmarva, and coastal areas which
remain in the 40s and 50s. Current Frost and Freeze headlines
remain unchanged and are in effect until 9 AM today.

Virtually, today and tonight will act as the `calm` before the
storm. Strong high pressure centered over interior New England
will shift off the coast of Cape Cod early this afternoon before
remaining situated south of Nova Scotia tonight. As it does so,
return flow will become more onshore resulting in moderating
temperatures with highs in the upper 50s to mid 60s. Scattered
to broken low clouds will develop as the day progresses from
southeast to northwest as moisture increases across the area but
overall should be nothing of significance.

By tonight, an increase in clouds associated with the developing
coastal storm off the Carolinas will begin to fan into the Mid-
Atlantic region. This cloud cover will limit radiational cooling
and keep temperatures at bay. As a result, lows will mainly range
in to the mid 40s to mid 50s with upper 30s to low 40s in the
higher terrain. Aside for a stray shower late, dry conditions
will prevail.

&&

.SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/...
Saturday will feature mostly cloudy to overcast skies with
temperatures moderating further into the upper 60s to low 70s in
most areas. While most are likely to remain dry during the
daytime Saturday, some scattered showers will begin to
overspread the area, moving into areas across the coastal plain
SE of I-95 through the afternoon. Easterly winds will begin to
increase some, especially later in the day closer to the coast.

Things really start to go downhill on Saturday night as a
coastal low approaches from the south. Rain is expected to
continue overspreading the area, with around a 70-90% chance of
rain region-wide. Winds begin to increase, especially over the
water and along the immediate coastline with gusts getting near
40-50 mph by daybreak.

***Significant impacts possible from a strong coastal storm
 Sunday through Monday***

Overview: We continue to closely monitor the anticipated
development of a potentially significant coastal storm near the
North Carolina coast along a stalled frontal boundary beginning
Saturday. 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: There have been no significant changes to the
forecast or messaging for the storm with this update. There
still remains a fair amount of certainty regarding the details
of the evolution of the coastal storm and its ultimate degree of
impacts. There are still 2 potential solutions, which are most
evident in the differences between the 00Z GFS and ECMWF model
runs. A stronger storm that tracks closer to the coast will
result in much more severe impacts (similar to the 00Z GFS
solution). A somewhat weaker storm that tracks farther offshore
will result in less severe, but still potentially significant
impacts to the immediate coast. 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
Saturday or Saturday night. All previously issued watches remain
in effect at this time due to the continued uncertainty in
timing, severity, and inland extent of impacts.

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. If
the current track holds and the coastal storm does end up just
offshore or even making landfall over Delmarva, strong winds are
expected, sustained near 30-40 mph (perhaps near 50 mph along
the immediate coast) with gusts possibly near 60-70 mph along
the coast by Sunday afternoon, Sunday night, and early Monday.
There is potential for these strong winds to continue well into
Monday. Gusts upward of 30-50 mph may extend inland to about the
I-95 corridor and Philadelphia metro area. While there is still
some uncertainty in how long strong winds last, there is at
least high enough confidence that counties bordering the
Atlantic Ocean will either see sustained winds or frequent wind
gusts at/above criteria for a High Wind Warning. As a result,
the High Wind Watch remains in effect for Atlantic coastal NJ
and DE, and their respective counties as periods of 40+ mph
sustained winds and/or frequent gusts near 60 mph are
increasingly likely. Would not be surprised to see a Wind
Advisory for more inland counties, but will wait to issue
anything until confidence on inland extent of the winds is
higher. Long story short, power outages and tree damage are
possible, especially toward the coast.

In addition to the wind, heavy rain is forecast, and a SLIGHT
(2/4) Risk Excessive Rainfall Outlook is in place for the I-95
corridor and points south and east for Sunday through Sunday
night. A widespread 1-3 inches of rain is forecast across our
entire area, with locally higher amounts of 3-5 inches possible,
especially within the SLGT risk area near the coast. While that
sounds like a lot, it is important to keep in mind that this
will be falling over a 36 to 48 hour period. It has been quite
dry as well. Given this, the thinking is that flooding due to
heavy rain alone will be limited to poor drainage and urban
areas. However, that much 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 couple days.

&&

.LONG TERM /TUESDAY THROUGH THURSDAY/...
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 Tuesday into 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 /10Z FRIDAY THROUGH TUESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Today...VFR. Clear skies early will transition to a mix of
SCT/BKN clouds around 4000 feet as the day progresses. Northeast
winds initially, will settle out of the east-southeast around
5-10 kt. Moderate-high confidence.

Tonight...Primarily VFR with BKN ceilings around 3500-4000 feet.
Isolated instances of MVFR ceilings possible. Easterly winds around
5 kt or less, becoming variable/calm at times. Moderate-high
confidence.

Outlook...

Saturday...Starting out VFR though conditions likely come down
late in the day as showers and low clouds overspread the area,
potentially bringing MVFR conditions to the South Jersey
terminals and possibly KPHL/KILG. Northeast wind gusts near 20
kt at KACY.

Saturday Night...MVFR/VFR conditions with light to moderate
rain and lower clouds overspreading the area. Highest chance for
restrictions at the South Jersey terminals. Northeast wind
gusts 25-30 kt at KACY, 20-25 kt at the I-95 terminals and KMIV,
and 15-20 kt at the Lehigh Valley Terminals.

Sunday through Monday...MVFR to IFR conditions expected with
moderate to heavy rain moving through and gusty winds.
Northeast wind gusts up to 50 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.
Wind gusts could get near 20 kt at times.

&&

.MARINE...
No marine headlines are in effect through tonight. Easterly
winds around 10-20 kt this morning will settle out of the east-
southeast this afternoon around 10-15 kt and continue through
tonight. Seas of 2-4 feet expected. Fair weather.

Outlook...

Saturday...Conditions expected to begin to deteriorate, with
SCA conditions expected later in the day. Seas build to around 5
to 7 feet with winds increasing out of the east to around 20-30
kt. A Small Craft Advisory was issued for portions of the
Atlantic coastal waters to highlight this.

Saturday Night through Tuesday...A Storm Watch remains in place
through Monday for all marine zones except the upper Delaware
Bay. Northeast winds 35-45 kt and gusts up to 50-55 kt expected
within the Atlantic coastal waters and mouth of Delaware Bay.
Gale Watch in effect for the upper Bay as winds should be
lighter. Dangerous seas upward of 15 to 20 feet expected.
Conditions will begin to improve by Monday night into Tuesday,
though gale force winds may linger as the storm weakens. Periods
of moderate to heavy rain and sea spray restricting visibility
through Monday.

&&

.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. Coastal Flood Advisories
remain in effect to highlight this threat. The Saturday high
tide could also experience minor coastal flooding, mainly near
southern Cape May County, southern coastal Delaware and Delaware
Bay, but confidence is lower on this at the moment and the
Advisory was not extended to Saturday just yet.

There is an increasing risk of moderate to potentially major
coastal flooding impacts beginning Sunday through Monday as a
strong coastal storm impacts the region. Guidance 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 Watch remains in
effect to highlight this threat for the high tides Sunday
through Monday.

Significant beach erosion and dune breaching are possible along
the entire New Jersey Shore and 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...Freeze Warning until 9 AM EDT this morning for PAZ054-055-061-
     062.
     Frost Advisory until 9 AM EDT this morning for PAZ060-101>106.
NJ...Coastal Flood Watch from Sunday afternoon through Monday
     evening for NJZ016.
     Coastal Flood Advisory until 4 PM EDT Saturday for NJZ021>025.
     Coastal Flood Watch from Sunday morning through Monday evening
     for NJZ012>014-020>027.
     High Wind Watch from Sunday morning through late Sunday night
     for NJZ013-014-020-022>027.
     Freeze Warning until 9 AM EDT this morning for NJZ001-007.
     Frost Advisory until 9 AM EDT this morning for NJZ008>010-015-
     017>022-027.
DE...Coastal Flood Watch from Sunday afternoon through Monday
     evening for DEZ001.
     Coastal Flood Advisory until 4 PM EDT Saturday for DEZ002>004.
     Coastal Flood Watch from Sunday morning through Monday evening
     for DEZ002>004.
     High Wind Watch from Sunday morning through late Sunday night
     for DEZ003-004.
MD...None.
MARINE...Gale Watch from Saturday evening through Monday evening for
     ANZ430.
     Storm Watch from Saturday evening through Monday evening for
     ANZ431-450>455.
     Small Craft Advisory from 10 AM to 6 PM EDT Saturday for
     ANZ451>455.

&&

$$

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