571
FXUS61 KPHI 172340
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
740 PM EDT Thu Sep 17 2026

.WHAT HAS CHANGED...
Updated Aviation section with 00Z TAF cycle.

&&

.KEY MESSAGES...
1. A cold front crosses the area overnight with showers.

2. A series of cold fronts and low pressure systems will bring
unsettled weather to the area starting Saturday night and continuing
through at least Tuesday. Heavy rain from time to time is possible.

&&

.DISCUSSION...
A cold front crosses the area overnight with showers.

The latest surface map shows a weak area of low pressure across
New York State and a cold front into Pennsylvania. A mild and
increasingly flow ahead of these features has brought some
showers to parts of the region so far today. More showers and
possibly a tstm will continue to develop across PA/MD and move
east into NJ/DE this evening and into the overnight. We`ll
continue with the higher CHANCE and low-end LIKELY pops for
these time periods. Rains will end by dawn but some patchy rural
fog is possible.

While severe weather is not expected, there will likely be some
short period downpours this evening with some rainfall rates
around an inch per hour possible. The moderately fast motion of
the cells will preclude any significant totals however. Average
rainfall of 0.1 to 0.3 inches possible with a few totals closer
to 1.0 inch possible.

KEY MESSAGE 2... A series of cold fronts and low pressure systems
will bring unsettled weather to the area starting Saturday night
and continuing through at least Tuesday. Heavy rain from time
to time is possible.

High pressure will be centered over the Province of Quebec Saturday
morning, and then the center of the high will shift towards the
Canadian Maritimes and the Gulf of Maine by Saturday evening.
Overall, conditions should start out mostly sunny Saturday morning,
then mid and high clouds will build into the region throughout the
day. Mild and pleasant otherwise with highs in the 70s to near 80.

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. A cold front passes
through the region behind the departing low, and that front will sag
south towards Delmarva by Monday morning, where it will stall out.

WPC has a Marginal risk for Excessive Rainfall (1 out of 4) for the
region Sunday and 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 will mostly be capped at 30 to 50 percent
(chance).

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Tonight... Restrictions mostly MVFR in showers and possibly a
few tstms (greater chances for tstms across KACY/KMIV).
Primarily VFR between the showers. Patchy fog possible late
with MVFR possible then too. South to Southwest winds around 5
knots or less becoming NW by dawn. Medium confidence.

Friday... VFR expected. Decreasing clouds early then mostly
sunny expected. North winds increasing to around 10 kts with
gusts to 15 kts. Medium/high confidence.

Outlook...

Friday night through Saturday...VFR. NSW.

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

&&

.MARINE...
No significant marine headlines for tonight or Friday. Scattered
showers or perhaps a TSTM this evening into the early overnight
period. Local higher winds in VCNTY of TSTMs.

Outlook...

Friday night through Monday...Sub-SCA conditions through Sunday.
SCA headlines may be needed on Monday for east to northeast winds
15 to 20 kt with gusts up to 25 kt and 4 to 6 ft.

VSBY restrictions in showers and isolated thunderstorms Sunday
through Monday.

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...None.

&&

$$

DISCUSSION...MPS/PO
AVIATION...AKL/MJL/MPS/PO
MARINE...MPS/PO