958
FXUS61 KPHI 191720
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
Issued by National Weather Service New York NY
120 PM EDT Wed Aug 19 2026

.WHAT HAS CHANGED...
Updated Aviation Section for 18Z TAFs.

&&

.KEY MESSAGES...
1. High pressure nudges in for today with mainly dry and
comfortable conditions. Some patchy fog possible this
morning.

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...High pressure nudges in for today with mainly
dry and comfortable conditions.

High pressure building in today will yield mostly sunny skies
with seasonable temperatures topping out in the mid to upper 80s
and lower, more comfortable humidity levels. The only other
thing of note for today is a very low chance (15-20%) of showers
forming along the sea-breeze this afternoon. No significant
impacts are expected from this though.


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 tonight. 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 tonight.

As noted by the previous shift, there remains considerable
differences in timing with the frontal passage though the area.
Most of the 00Z suite of guidance has continued to slow down
the forward progression of the front. With the continued slowing
of the front, this will yield more of a convective/hydro threat
as some of the mid-range CAM guidance shows potential for
multiple rounds of storms on Thursday. Some CAMs, such as the
00z HRRR and NAMNest both had a convective line pushing through
our area on Thursday evening. There is some uncertainty but
confidence is increasing in that there will be some severe
weather and flash flooding concerns. WPC has actually added a
Slight (2/4) Risk for excessive rainfall from the I-95 corridor
on east. This makes sense since guidance has PWATs around 2 to
2.3". Soundings show a long/skinny CAPE profile as well, which
usually results in more of a hydro than severe weather threat.
However, with moderate instability and decent shear, severe
weather is definitely on the table, mainly in the form of
damaging wind gusts. This is especially true if linear clusters
of storms form upstream and move towards our area, like some of
the CAMs suggest. The Marginal (1/5) Risk was expanded
northward, now going to I-78. If we see another guidance cycle
similar to this morning however, it would not be a surprise for
the introduction of a Slight (2/5) Risk. The main timing window
is for Thursday afternoon and evening, though some showers may
develop in the morning ahead of the main window.

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.

High pressure looks to nudge in next week, which should shake
the unsettled pattern.

&&

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

Rest of Today...VFR. West-southwest winds around 5-10 kt. High
confidence.

Tonight...VFR with increasing high clouds. West-southwest winds
around 5 kt or less early, becoming light and variable
overnight. Moderate-high confidence.

Thursday...VFR in the morning with restrictions likely
developingin the afternoon (primarily after 16Z) as widespread
showers and thunderstorms are likely at all terminals. Winds
will vary depending on location, with northern terminals
experiencing east-northeast winds around 5 kt where southern
terminals will encounter southeasterly winds around 5-10 kt.
Winds may locally become gusty and erratic near any storm.
Moderate-low confidence overall.

Outlook...

Thursday Night...Restrictions likely continue into Thursday
Night.

Friday through Friday Night...Primarily VFR, though cannot rule
out some showers/thunderstorms from KILG on south which could
result in some restrictions.

Saturday through Saturday Night...Restrictions expected with
showers and thunderstorms anticipated.

Sunday...Primarily VFR though cannot rule out a few showers and
thunderstorms.

&&

.MARINE...
Sub-SCA conditions expected through tonight. Winds out of the
west/southwest around 10 kt or less. Seas 1 to 2 feet.

Outlook...

Thursday through Sunday...No marine headlines anticipated.
Showers and thunderstorms expected at times on the waters,
especially Thursday and Saturday.

Rip Currents...

For today and Thursday, westerly winds 5 to 10 mph early will
shift southerly by the afternoon (more southwest today, more
southeast on Thursday). Breaking waves will average around 1 to
2 feet. 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/Hoeflich/Staarmann
AVIATION...DeSilva/Hoeflich/Staarmann
MARINE...DeSilva/Hoeflich/Staarmann