678
FXUS61 KPHI 131106
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
706 AM EDT Sun Sep 13 2026

.WHAT HAS CHANGED...
Forecast for tonight still on track. Warm front slowly progressing
northward through the region at this hour.

&&

.KEY MESSAGES...
1. Low pressure lifting through the region through the morning
will produce showers and thunderstorms with the potential for
flash flooding across portions of the forecast area.

2. A cold front Thursday into Friday may bring some showers and
thunderstorms.

&&

.DISCUSSION...
KEY MESSAGE 1...Low pressure lifting through the region through
the morning will produce showers and thunderstorms with the
potential for flash flooding across portions of the forecast
area.

The low and associated warm front is slowly lifting through
Delmarva overnight. As it does so, expect low level moisture
advection to continue. For areas south of the warm front
already, dewpoints were quick to increase into the lower to mid
70s. Precipitable water values are still expected to increase
above 2 inches. Given the high precipitable water values and
relatively deep warm cloud layer, rain rates up to 2 inches per
hour will be possible.

While the heavy rain won`t last long, this could be enough to
lead to flash flooding particularly in urban areas. 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. The Flood Watch for flash flooding in
these areas continues through Noon.

This system will be fairly progressive, lifting to Long Island
by around midday Sunday. Precipitation tapers off late this
morning the low departs. A weak cold front swings through
Sunday afternoon behind the low followed by a secondary cold
front late tonight/early Monday Morning. Some light rain
showers will be possible with the secondary cold front, but with
dry air already filtering in to the area by then, do not expect
much more than light rain showers.


KEY MESSAGE 2...A cold front Thursday into Friday may bring some
showers and thunderstorms.

An upper-level trough across central into eastern Canada is forecast
to push a cold front into our area at the end of next week. While
the guidance, including ensembles, are in decent agreement showing
this trough, there are significant differences with the
amplification and therefore speed of the trough. This will have
impacts to the cold front itself. If the main energy slides far
enough north of our area, the front may tend to be slower moving.
This scenario would open the door for a greater chance for a round
of convection. A faster movement to the front would lessen the
length of convection over our area. The front may then stall to our
south into next weekend, with one or more possible waves of low
pressure tracking along it with time. A plume of deeper moisture
looks to get drawn northward ahead of this front, therefore some
heavy rain potential may exist with it and this also depends on
whether it stalls or not. Confidence remains low during this time
frame.

&&

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

Today...Sub-VFR in SHRA in the morning, then becoming VFR by
20/21z or shortly after that as clouds scatter out. W-NW winds
generally around 5-10 knots. Moderate confidence.

Tonight...Prevailing VFR, though some clouds around 4000ft AGL
will be possible, especially through the first part of the
night.

Outlook...

Monday...VFR. North-northwest winds gusts 20-25 knots possible
during the day.

Tuesday and Wednesday...VFR.

Thursday...Mostly VFR. A few showers possible.

&&

.MARINE...
Winds and seas should stay below Small Craft Advisory conditions
through tonight. Some visibility restrictions are possible in
showers and fog through the morning. Expect a wind shift from
southeasterly to northwesterly during the day on Sunday.

Outlook...

Monday...There is a slight chance (20%) of Small Craft Advisory
northwesterly wind gusts (25 knots). At this point, the chance
is too low to issue an SCA, but will be monitoring trends over
the next 24 hours.

Tuesday through Thursday...The conditions are anticipated to be
below Small Craft Advisory criteria.

Rip Currents...

Sunday...Southwest winds around 10-15 mph in the morning
diminish to around 5-10 mph from the west in the afternoon.
Breaking wave heights will range between 1 to 3 feet. An
underlying 1 foot southeast swell around 8 to 10 seconds will
continue. Given these conditions, have opted to go with a
LOW risk for rip currents for all beaches.

Monday...West-northwest winds will be around 15-20 mph with seas
will remaining at 1-2 feet. The underlying 1 foot 8 to 10 second
southeasterly swell remains. Given these conditions, currently
forecasting a LOW risk for rip currents for all beaches.

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

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Flood Watch until noon EDT today for PAZ070-071-103>106.
NJ...Flood Watch until noon EDT today for NJZ008>010-012>020-026-
     027.
DE...Flood Watch until noon EDT today for DEZ001.
MD...None.
MARINE...None.

&&

$$

DISCUSSION...Fitzsimmons/Gorse/SJ
AVIATION...Fitzsimmons/Gorse/SJ/PO
MARINE...Fitzsimmons/Gorse/SJ/MJL