844
FXUS61 KPHI 091103
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
703 AM EDT Thu Oct 9 2025

.SYNOPSIS...
High pressure will continue to build into the area through
tonight. It will then shift offshore Friday into Saturday. A
coastal storm with potentially significant impacts is expected
to affect the region by Sunday and into early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Expansive and strong Canadian high pressure will be in complete
control through tonight. This surface high currently situated
over the eastern Great Lakes will shift east today, before
settling over southern New England tonight. As a result, clear
skies and light to moderate breezes around 5-15 mph continue
across the Mid-Atlantic region. Some patchy frost may develop in
the Poconos over the next few hours, but will be rather
sporadic in nature as winds remain elevated. Otherwise, expect
wall to wall sunshine today with highs topping out in the low to
mid 60s with higher elevations only in the mid to upper 50s!

Tonight, winds will diminish and become light to nearly calm as
the surface high moves within close proximity to the area. With
the crisp Canadian airmass in place along with clear skies, all
these ingredients will equate to an exceptional night for
radiational cooling to occur. Subsequently, low temperatures are
forecast to fall as far as the upper 20s to low 30s across
portions of the Lehigh Valley, Poconos, and northern New Jersey
where Freeze Watches have been upgraded to Freeze Warnings.
Elsewhere across southeast Pennsylvania and much of interior and
central New Jersey, lows will bottom out in the low to mid 30s
where Frost Advisories have been issued. For the immediate urban
corridor and Delmarva, lows will primarily range in upper 30s
to mid 40s. Some low clouds are possible near the coast
overnight as flow becomes a bit more onshore, keeping temps
along the coast warmer in the upper 40s to low 50s.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY/...
Moderating temperatures and increasing cloud cover will be the
theme as we close out the week and head into the weekend. Most
areas will remain dry through the daytime Saturday, though a few
showers could develop by Saturday afternoon across the coastal
plain.

Shortwave ridging will briefly pass just north of the area on
Friday as a sharp trough axis deepens to our southwest. At the
surface, strong high pressure in place to start the day Friday
will begin to shift offshore, where it will remain through
Saturday.

By Friday, cold advection will have ceased as the high pressure
shifts offshore. This will allow for some airmass modification,
and afternoon high temperatures should easily reach into the
mid 60s under mostly sunny skies. Surface winds will shift
onshore, which could allow for some marine stratus to push in
from the coast later in the day. Cirrus will likely also begin
arriving later in the day. East to southeast winds 5-10 mph.

Friday night will be much more mild compared to the previous
night thanks to onshore winds advecting in higher dewpoints and
increasing cloud cover. Forecast low temperatures by Saturday
morning are in the 40s to low 50s, though some sheltered areas
north of I-78 could dip into the mid to upper 30s again with
frost development possible. Tonight`s freeze in those areas will
likely preclude the need for any frost hazards though.

Saturday will feature mostly cloudy to overcast skies with
temperatures moderating further into the upper 60s to low 70s in
most areas. While most areas are likely to remain dry during
the daytime Saturday, a few showers could develop across the
coastal plain SE of I-95 into the afternoon. Easterly winds will
begin to increase some, especially later in the day closer to
the coast.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
For the long term period over the weekend and into early next
week, the main feature of interest will be the development of a
potentially significant coastal storm near the North Carolina
coast along a stalled frontal boundary. This storm is
anticipated to strengthen and lift northward Sunday into early
next week.

There remains a fair amount of certainty regarding the details
of the evolution of the coastal storm and its ultimate degree of
impacts. The primary impacts will be from coastal flooding,
beach erosion, strong to potentially damaging winds, and heavy
rain. The heaviest rainfall and strongest winds are still
anticipated to be near the Atlantic coast.

Things start to go downhill on Saturday night as a coastal low
approaches from the south. Rain is expected to being
overspreading the region, especially near the coast, while areas
in the Lehigh Valley/Poconos/northern NJ likely stay dry
through the night. Winds begin to increase, especially over the
water and along the immediate coastline with gusts getting near
40-50 mph by daybreak.

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,
strong winds are expected, sustained near 30-40 mph (perhaps
near 50 mph along the immediate coast) with gusts possibly near
60 mph or greater along the coast by Sunday afternoon and Sunday
night. 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. Wind hazards will likely be needed in
a future update.

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. We are not fully in the QPF period yet, but the WPC
longer-range rainfall products suggest a widespread 1-2+ inches
of rain across our entire area, with locally higher amounts of
3-5 inches certainly possible, especially within the SLGT risk
area. NBM probability of 2+ inches of rain for New Jersey and
Delmarva is about 40-60%, which is actually quite high being 4-5
days out. Strong northeast winds will also result in water
piling up along the coast, with moderate to even major coastal
flooding possible Sunday and Monday (more on that below in the
Tides/Coastal Flood section).

With all that being said, there remains a lot of uncertainty in
the track of the coastal low, even being within 4 days of the
event. 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. A closer and
slower evolution would bring more significant impacts while a
track further away still will likely bring hazards, though not
as severe. Stay tuned to the latest briefing packages and
forecast updates as the forecast continues to change.

Things look to quiet down by Tuesday and Wednesday as the
system pulls away with rather benign weather and seasonable
temperatures for mid-October.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Today...VFR/SKC. North-northeast winds around 7-12 kt. High
confidence.

Tonight...VFR/SKC. A few low clouds possible near KACY late.
Northeast winds around 5 kt or less, becoming calm at times.
High confidence.

Outlook...

Friday...VFR. No significant weather.

Saturday...Restrictions possible in low clouds, especially
toward the coast. Gusty winds possible overnight.

Sunday through Monday...Restrictions likely in low clouds and
periods of rain. Strong and gusty northeast winds.

&&

.MARINE...
The Small Craft Advisory on the Delaware Bay is now in effect
until 10 AM this morning. The Small Craft Advisories on the
Atlantic coastal waters remain unchanged through this afternoon
and tonight.

North-northeast winds around 15-20 kt with gusts up to 25-30 kt
are expected to continue this morning, before beginning to
subside by early afternoon. For tonight, winds will become east-
northeast around 10-20 kt. Seas around 3-6 feet through
tonight. Fair weather outside of SCA conditions.

Outlook...

Friday through Friday night...No marine hazards expected. Fair
weather.

Saturday...Winds and seas building, potential to advisory
levels. A chance of showers.

Saturday night through Monday...A strong coastal storm will
begin to impact the region. Gale force winds developing Saturday
night, with potential for storm force winds Sunday through
Monday. Seas building 12-20 feet. Showers and sea spray
restricting visibility.

&&

.TIDES/COASTAL FLOODING...
A combination of high astronomical tides (King Tides) and
modest northeast winds is expected to result in areas of minor
coastal flooding with this morning`s high tide along portions of
the Atlantic coast and Delaware Bay. Minor coastal flooding is
also forecast with the Friday morning 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.

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 are growing
increasingly concerned about the potentially 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 southern New Jersey (Barnegat Bay and southward) and
Delaware, and Delaware Bay. A Coastal Flood Watch was issued to
highlight this threat for the high tides Sunday through Monday.

Moderate to potentially major coastal flood impacts are
possible in Monmouth and Middlesex Counties, however confidence
in these areas is much lower, as this threat will be much more
directly tied to the evolution of the track and intensity of the
coastal low pressure center. Significant beach erosion is
possible along the entire New Jersey Shore and Delaware beaches.
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 from 11 PM this evening to 9 AM EDT Friday for
     PAZ054-055-062.
     Frost Advisory from 2 AM to 9 AM EDT Friday for PAZ060-061-
     101>106.
NJ...Coastal Flood Watch from Sunday afternoon through Monday
     evening for NJZ016.
     Coastal Flood Advisory until 3 PM EDT Friday for NJZ021>025.
     Coastal Flood Watch from Sunday morning through Monday evening
     for NJZ020>027.
     Freeze Warning from 11 PM this evening to 9 AM EDT Friday for
     NJZ001-007.
     Frost Advisory from 2 AM to 9 AM EDT Friday for NJZ008>010-015.
     Coastal Flood Advisory until 3 PM EDT this afternoon for
     NJZ013-014-020-026-027.
DE...Coastal Flood Watch from Sunday afternoon through Monday
     evening for DEZ001.
     Coastal Flood Advisory until 3 PM EDT Friday for DEZ002>004.
     Coastal Flood Watch from Sunday morning through Monday evening
     for DEZ002>004.
MD...None.
MARINE...Small Craft Advisory until 10 AM EDT this morning for ANZ430-
     431.
     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 until 2 PM EDT this afternoon for ANZ450.
     Small Craft Advisory until midnight EDT tonight for ANZ451>453.
     Small Craft Advisory until 6 AM EDT Friday for ANZ454-455.

&&

$$

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