101
FXUS61 KPHI 132032
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
432 PM EDT Thu Aug 13 2026

.WHAT HAS CHANGED...
Updated tidal flooding and SRF discussion.

&&

.KEY MESSAGES...
1. Cold front continues to sink south through Friday, bringing
gradually improving conditions with high pressure overhead
Saturday and the first half of Sunday.

2. Unsettled weather returns Sunday into Monday.

3. One last round of spotty minor tidal flooding expected
tonight before tides continue to fall through the end of the
week.

&&

.DISCUSSION...
KEY MESSAGE 1...Cold front continues to sink south through
Friday, bringing gradually improving conditions with high
pressure overhead Saturday and the first half of Sunday.

The stationary front that has lingered across the region the
last few days will continue to sink south as a cold front
through tomorrow, allowing gradually improving conditions to
filter in. The rest of today and tonight should generally stay
dry, though cooler temperatures and lower humidity will not
arrive until Friday and especially Saturday.

Some showers are possible late Friday into Friday night as the
cold front finally shifts far south enough to allow surface high
pressure to be overhead Saturday and into early Sunday. The
forecast Saturday looks to be the driest, coolest, and least
humid day through the weekend. That being said highs on Saturday
are only a few degrees lower than Friday, so it won`t be
dramatically cooler.

High pressure will not last, however, and shift offshore
Sunday, bringing return flow back across the region, allowing
temperatures to creep back up into the mid to upper 80s and the
humidity to return. The morning will be largely dry with chances
for rain returning by the afternoon.

KEY MESSAGE 2...Unsettled weather returns Sunday into Monday.

The next storm system arrives Sunday into Monday as a surface
low moves across the Great Lakes, Ohio Valley, and eventually
the Mid Atlantic, bringing the chance for showers and
thunderstorms.

The biggest change with previous guidance is the spread in the
timing of precipitation. There are some models that show
precipitation moving in as early as 06 to 12Z Sunday Morning.
That being said, there are still a few models not showing rain
move in until the afternoon. The net result of this uncertainty
is that there are PoPs in place from late Saturday Night all the
way through Monday. This long period of rain mention is an
artifact of the differences between models in the timing, but
I don`t expect rain to occur for that entire period.

Regardless of the timing, the primary threat at this point is
heavy rain leading to flash flooding. Global guidance shows
PWAT values surging back into the 2" range, increasing the
potential for heavy downpours within any thunderstorms that
develop. As a result, WPC does have much of the Northeast and
Mid Atlantic in a Marginal risk in the Excessive Rainfall
Outlook.

Depending on the timing of the storms, some modest instability
may be in place to support a severe potential. That said, the
overall synoptic level forcing is limited with the main driving
force being a weak upper level trough. At this point, it remains
too early to lock down any specifics for severe and flash
flood, but we will need to monitor the potential over the next
several days.

KEY MESSAGE 3...One last round of spotty minor tidal flooding expected
tonight before tides continue to fall through the end of the
week.

With the New Moon having occurred yesterday, astronomical
tides for this evening`s high tide cycle will be near minor
flooding thresholds for many places along the Atlantic coasts of
New Jersey and Delaware, and Delaware Bay. Only spotty minor
flooding is possible with this evening`s high tide and this
should be the last high tide cycle with any tidal flooding.

Tidal flooding is not currently forecast for the Eastern Shore of
the Chesapeake Bay or tidal Delaware River.

&&

.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

This afternoon...VFR. W-NW winds 10 to 15 kts.

Tonight...VFR. Winds becoming light and variable.

Friday...VFR. W wind around 10 knots.

Outlook...

Friday night...Primarily VFR though restrictions possible
(30-40%) with scattered showers/isolated thunderstorms.

Saturday through Sunday Morning...VFR. No significant weather.

Sunday Afternoon through Monday...Sub-VFR conditions likely (60-70%)
at times with widespread showers and a few embedded thunderstorms
anticipated.

Tuesday...VFR conditions expected.

&&

.MARINE...
No prevailing marine hazards expected through Friday.

Outlook...

Friday through Sunday...No marine headlines expected.

Sunday Night through Monday...SCA conditions possible (30-40%) as
seas near 5 feet and southerly wind gusts near 25 kt.

Tuesday...No marine headlines expected.

Rip Currents...

Generally tranquil conditions expected at the beaches through
Saturday. Winds turn onshore but will be light - under 10 MPH.
An 8 to 10 second period swell will also be present, but
breaking waves should be 2 feet or lower. This will result in a
LOW risk for rip currents at all beaches for Friday and
Saturday.

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

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...None.

&&

$$

DISCUSSION...Hoeflich/Johnson/MJL
AVIATION...Franklin/MJL
MARINE...Hoeflich/Johnson/MJL