444
FXUS61 KPHI 121058
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
658 AM EDT Sat Sep 12 2026

.WHAT HAS CHANGED...
A Flood Watch is now in effect for portions of southeast
Pennsylvania, northern Delaware, and New Jersey for late tonight
through Sunday morning.

The Aviation section was updated for the 12Z TAFs.

&&

.KEY MESSAGES...
1. Low pressure lifting through the region tonight through
Sunday morning will produce showers and thunderstorms, as well
as locally heavy rain resulting in a flash flood risk for
portions of the forecast area.

2. During the latter half of next week, a slow moving cold
front looks to make its way southward across the area bringing
the potential for showers and storms.

&&

.DISCUSSION...
KEY MESSAGE 1...Low pressure lifting through the region tonight
through Sunday morning will produce showers and thunderstorms,
as well as locally heavy rain resulting in a flash flood risk
for portions of the forecast area.

High pressure over the area moves out to sea later today. Return
flow sets up behind the high, and low level moisture will
increase over the area. Meanwhile, low pressure will organize
and develop over the Mid-Atlantic. A warm front associated with
that low will lift north through the region this evening, and
then southerly flow will allow dew points to rise well into the
60s and low 70s. PWATs will rise to 2-2.25 inches.

Low pressure then follows north through the region late tonight
through Sunday morning. This system will be fairly progressive,
lifting from Delmarva around midnight tonight to Long Island by
late Sunday morning. However, due to the high moisture content
in the atmosphere, there will be a 6-8 hour window during the
early morning hours on Sunday where as much as 1-2 inches of
convective rain will fall. The primary area of concern is the
I-95 corridor and surrounding urban areas and small streams
where flash flooding is more possible given any rapid runoff.

Precipitation tapers off Sunday morning as low pressure
departs. A cold front swings through Sunday afternoon behind the
low, and then a secondary front may pass through the region
Sunday night.


KEY MESSAGE 2...During the latter half of next week, a slow
moving cold front looks to make its way southward across the
area bringing the potential for showers and storms.

Once we get through this weekend, attention will turn to
Thursday and Friday of next week. It should be first noted there
is a lot of spread in the forecast guidance at this time given
this is about a week away. But overall, the signal in guidance
is for a slow moving cold front to move southward through the
area late next Thursday into Friday bring the potential for
showers and some storms. PWAT values along this front look to
potentially be quite high (around 2 inches) but there remains
some questions about how much instability there will be as well
as the speed and timing of the front as it moves through. The
upshot of all this is that while forecast confidence is low,
this period will need to be monitored for heavy rain potential.

&&

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

Today...VFR. Any SHRA/TSRA will hold off until the evening
hours. S-SE winds 5 to 10 kt. High confidence.

Tonight...IFR CIGs/VSBYs in SHRA and scattered TSRA. Light E-SE
winds. Moderate confidence.

Sunday...Sub-VFR in SHRA in the morning, then VFR. W-NW winds 5
to 10 kt in the afternoon. Moderate confidence.

Outlook...

Sunday night through Wednesday...VFR.

&&

.MARINE...
Sub-Small Craft Advisory conditions today, tonight, and Sunday.
E-SE winds 10 to 15 kt with gusts up to 20 kt today and tonight,
then W-SW on Sunday. Seas 2 to 4 ft.

VSBY restrictions in showers, scattered thunderstorms, and fog
late tonight through early Sunday afternoon.

Outlook...

N/NW winds will increase later Sunday night into Monday and could
briefly reach Small Craft Advisory levels. Winds will diminish by
next Tuesday into Wednesday but seas look to increase to around 4-5
feet by this time.

Rip Currents...

Today...Southeast winds will increase to around 10 to 20 mph
with breaking wave heights ranging between 1 to 3 feet. There
will also be a 1 to 2 foot southeast swell around 8 to 10
seconds. Given strengthening onshore flow, have opted to
maintain a MODERATE risk for the development of dangerous rip
currents at both the Jersey Shore and Delaware Beaches.

For Sunday...Southwest winds around 10 to 20 mph in the morning
will diminish to around 5 to 10 mph in the afternoon. Breaking
wave heights will range between 1 to 3 feet. An underlying
southeast swell around 8 to 10 seconds will continue. Given
these conditions, have opted to go with a MODERATE risk for rip
currents for Ocean, Atlantic and Cape May Beaches with a LOW
risk for Monmouth and Delaware Beaches.

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

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Flood Watch from late tonight through Sunday morning for
     PAZ070-071-103>106.
NJ...Flood Watch from late tonight through Sunday morning for
     NJZ008>010-012>020-026-027.
DE...Flood Watch from late tonight through Sunday morning for
     DEZ001.
MD...None.
MARINE...None.

&&

$$

DISCUSSION...Fitzsimmons/Gorse/MPS/WFO PHI
AVIATION...Fitzsimmons/Gorse/MPS/WFO PHI
MARINE...DeSilva/Fitzsimmons/Gorse/MPS/WFO PHI