122
FXUS61 KPHI 181841
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
Issued by National Weather Service New York NY
241 PM EDT Tue Aug 18 2026

.WHAT HAS CHANGED...
No significant changes to the forecast.

&&

.KEY MESSAGES...
1. A weak cold front will sink south through the region today,
with isolated thunderstorms possible this afternoon.

2. A stronger cold front is expected to cross through the
region on Thursday, resulting in greater chances for showers and
thunderstorms. Conditions look to remain unsettled through the
weekend, with daily chances of showers and storms each day.

&&

.DISCUSSION...
KEY MESSAGE 1...A weak cold front will sink south through the region
today, with isolated thunderstorms possible this afternoon.

The main story today will be the potential for some diurnally
driven isolated showers and storms this afternoon. Have started
to see a few showers develop along the sea-breeze over far southern
New Jersey over the past hour or so. With the front continuing
to sink south through the afternoon, a few more isolated showers
or storms may continue to develop, mainly south and east of the
I-95 corridor. Aside for some occasional lightning, no impactful
weather is anticipated with this activity.

Any convection will diminish around sunset with the loss of
diurnal heating. Conditions are then expected to remain dry
overnight, with some patchy fog possible mainly southeast of
I-95; where rain has fallen from this afternoon. Otherwise, high
pressure building in on Wednesday will yield mostly sunny skies
with seasonable temperatures and comfortable humidity levels.


KEY MESSAGE 2...A stronger cold front is expected to cross through
the region on Thursday, resulting in greater chances for showers
and thunderstorms. Conditions look to remain unsettled through
the weekend, with daily chances of showers and storms each day.

An upper-low will pivot around portions of Ontario and Quebec
through the end of the week, ultimately passing north of our
area Wednesday night. To the south of the upper low, broad
troughing will be in place across much of the Northeast and
Mid-Atlantic, where a few embedded shortwaves, will be pivoting
through the base of the trough. At the surface, a cold front
will begin to approach the area late Wednesday night.

As noted by the previous shift, there remains considerable
differences in timing with the frontal passage though the area.
Most of the 12Z suite of guidance has continued to slow down
the forward progression of the front. With the continued slowing
of the front, this may yield more of a convective/hydro threat
as some of the mid-range CAM guidance shows potential for
multiple rounds of storms on Thursday. Given the uncertainty,
confidence remains low whether there will be any severe weather
or flash flooding concerns; so we`ll have to continue to monitor
these potentials going forward. As of now, WPC has a Marginal
risk of excessive rainfall for the southern half of the area,
while SPC has a Marginal risk for severe weather across southern
Delaware. Regardless of convective/hydro threats, PoPs remain
in the 60-80% range for Thursday afternoon and evening.

Longer range NWP and AI guidance suggests that the pattern could
become unsettled Friday night and into the weekend. Depending on
how the frontal boundary evolution pans out on Thursday, will
impact the weather over the weekend. Most guidance does suggest
that the frontal boundary will stall over or in close proximity
of the area where several areas of low pressure may ride along
the stalled boundary through the weekend. PoPs currently are
mainly in the chance to likely range each day due to the present
uncertainties in timing and placement of these features and any
progression in the long wave pattern.

In terms of temps, highs and lows will both be quite seasonable
for late August, but humidity levels may be uncomfortable at
times.

&&

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

Rest of Today...Any lingering MVFR ceilings are expected to
improve to VFR at most terminals by 19-20Z. The exception is
KACY where MVFR ceilings may prevail for the remainder of the
afternoon. Isolated showers and thunderstorms are possible at
KMIV and KACY where have included PROB30 groups mainly between
20-00Z. Winds have been variable as of this afternoon, but
ultimately should settle out of the north-northwest around 4-8
kt. SE sea-breeze winds possible at KMIV/KACY late. Moderate
confidence overall.

Tonight...Prevailing VFR expected. Some patchy fog is possible
after 03Z at KMIV and KACY. Elsewhere, uncertainty remains high
so no mention at this time. Northwest winds around 5 kt or less,
becoming light and variable at times. High confidence, but
lower confidence with respect to any fog restrictions.

Wednesday...VFR with mostly clear skies. West winds around 5-10
kt. High confidence.

Outlook...

Wednesday night...VFR. No significant weather expected.

Thursday through Sunday...Periods of scattered showers and
storms are probable, with the greatest chance and coverage on
Thursday. Restrictions are possible with any showers or storms.

&&

.MARINE...
No marine headlines are in effect through Wednesday. Winds will
generally remain less than 10 kt through tonight. On Wednesday,
southerly winds will increase to around 10-15 kt. Seas around 2
feet through Wednesday.

Isolated showers and storms are possible this afternoon which
may cause localized restrictions and gusty winds. Otherwise,
fair weather is expected.

Outlook...

Wednesday night through Friday night...No marine headlines
expected. Showers and thunderstorms are likely to occur on both
Thursday and Friday afternoon/evenings.

Saturday through Sunday...SCA conditions possible due to seas
around 5 feet. Scattered showers and storm possible each day.

Rip Currents...

For today and Wednesday, northeast winds 5 to 10 mph this
morning will gradually turn to be more easterly at 5 to 10 mph
this afternoon. South to southwest winds near 10 mph on
Wednesday. Breaking waves will average around 1 foot. There
will continue to be a southeasterly swell with a 6 to 8 second
period. The result of these conditions is a LOW risk for the
development of dangerous and life threatening rip currents for
the Jersey Shore 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...DeSilva/Staarmann
AVIATION...DeSilva/Staarmann
MARINE...DeSilva