656
FXUS61 KPHI 181730
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
130 PM EDT Fri Sep 18 2026

.WHAT HAS CHANGED...
Confidence is increasing in a prolonged period of unsettled
weather most of next week.

Aviation section updated for the 18Z TAFs.

&&

.KEY MESSAGES...
1. Tranquil conditions are anticipated through the daytime
hours Saturday as high pressure centered north of the region
slides slowly eastward.

2. A series of cold fronts and low pressure systems will keep
unsettled weather over the area from Saturday night through
Thursday. Heavy rain is possible Sunday and Sunday night.

&&

.DISCUSSION...
KEY MESSAGE 1...Tranquil conditions are anticipated through the
daytime hours Saturday as high pressure centered north of the
region slides slowly eastward.

Mid-level ridging over portions of the Gulf Coast region
northeastward into the Mid-Atlantic today will continue to shift
slowly southwestward, with northwesterly flow aloft increasing
across the area tonight through Saturday. At the surface, High
pressure currently centered over portions of Ontario will shift
eastward through Saturday, passing north of the region on
Saturday before shifting offshore.

A warm and dry afternoon is in store with some clouds around.
Temperatures have warmed into the 70s to near 80 across the
area, with a few more degrees of warming anticipated through
this afternoon. Tonight, low temperatures will range from near
50 across portions of eastern PA and northern NJ to the mid 60s
across portions of Delmarva as a cooler airmass starts to settle
into the region. It should remain dry through the daytime hours
Saturday, though some clouds will remain around. It should be
notably cooler however, with high temperatures generally in the
low to mid 70s.


KEY MESSAGE 2...A series of cold fronts and low pressure
systems will keep unsettled weather over the area from Saturday
night through Thursday. Heavy rain is possible Sunday and Sunday
night.

High pressure moves out to sea Saturday night, and then low
pressure organizes and develops over the Midwest. A warm front
extending out from that low will lift north through the
Northeast Saturday night through Sunday morning. Showers first
develop after midnight Saturday night and continue through
Sunday morning.

As low pressure draws nearer to the region, southerly flow
increases throughout the Northeast and low level moisture
increases as well with surface dew points rising well into the
60s and low 70s and PWATs will be in excess of 2 inches. Low
pressure then passes through the southern Poconos and Lehigh
Valley Sunday afternoon and evening, resulting in more
widespread showers with isolated thunderstorms across most of
the area during that time. Locally heavy rain may develop from
time to time. As that low passes through the region, a cold
front will sag south through the region Sunday night, and the
axis of heavy rain will then track south towards the I-95
corridor and into the Philadelphia area. The front will stall
out over Delmarva Monday morning.

WPC continues the Slight Risk for Excessive Rainfall (2 out of
4) for Sunday and Sunday night for areas along the I-95 corridor
and points north and west. A Marginal Risk remains for the rest
of the region south and east of the I-95 corridor. A Marginal
Risk also continues for the entire region into Monday.

Several more disturbances will pass through the region Monday
and Tuesday, and this will keep rain chances in the forecast
during this time. For now, PoPs are limited to 30 to 50 percent
(chance) given the uncertainty of the timing and coverage of
showers. Low pressure looks to develop over the Mid-Atlantic
coast and will meander over the western Atlantic between the
Jersey Shore and south of Long Island during the midweek period.
Onshore flow and unsettled weather continues with below normal
temperatures.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Rest of today...VFR. North-northwest winds around 10 kt for all
but KMIV and KACY, where winds will be north-northeast. High
confidence.

Tonight...VFR. North-northeast winds of 5-10 kt. High
confidence.

Saturday...VFR. Northeast winds in the morning of 5-10 kt will
shift more easterly in the afternoon. High confidence.

Outlook...

Saturday night through Monday...Sub-VFR from time to time in
SHRA, isolated TSRA (mainly Sunday afternoon and Sunday night),
low stratus, and fog.

Tuesday through Wednesday...Sub-VFR conditions possible with
showers around with breezy northeast winds.

&&

.MARINE...
A Small Craft Advisory has been issued for NJ Atlantic coastal
waters north of Great Egg Inlet from 4 AM to 2 PM Saturday.
Northeast winds will increase to 15-20 kt with gusts near 25 kt
overnight tonight, with seas increasing to near 5 feet. Winds
will shift to east-northeast on Saturday and slowly diminish,
with diminishing seas as well. Outside of the advisory area,
winds are expected to remain below 25 kt with seas remaining
below 5 feet.

Outlook...

Saturday night through Sunday...Sub-SCA conditions. VSBY
restrictions in showers and isolated thunderstorms Sunday
afternoon and Sunday night.

Monday through Wednesday...SCA headlines may be needed starting
on Monday for east to northeast winds 15 to 20 kt with gusts up
to 25 kt and 4 to 6 ft. Gale force winds are possible Tuesday
with wind gusts exceeding 35 kts. Seas may build as high as 10
to 15 ft from Tuesday through Thursday.

VSBY restrictions in showers Monday through Wednesday.

Rip Currents...

Friday...North winds 10 to 15 mph with breaking waves of 1 to 2
feet with a light southerly swell with a 4 to 6 second period.
As a result, there is a LOW risk for the development of
dangerous and life threatening rip currents for the Jersey Shore
and Delaware Beaches.

Saturday...East winds 10 to 15 mph with gusts up to 20 mph.
Easterly swells with a 10 to 12 second period. As a result,
there is a MODERATE risk for the development of dangerous and
life threatening rip currents for Monmouth county and Ocean
county shores and a LOW risk for Atlantic county and coastal
Cape May county shores and Delaware Beaches.

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

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory from 4 AM to 2 PM EDT Saturday for
     ANZ450>452.

&&

$$

DISCUSSION...Cooper/MPS
AVIATION...Cooper/MPS
MARINE...Cooper/MJL/MPS