415
FXUS61 KPHI 171043
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
643 AM EDT Mon Aug 17 2026

.WHAT HAS CHANGED...
Updated Key Message 1.

Aviation section updated for 12Z TAFs.

&&

.KEY MESSAGES...
1. A cold front will pass through the region this afternoon and
evening.

2. A cold front is expected to cross through the region
Wednesday night into Thursday resulting in more shower and
thunderstorm chances.

&&

.DISCUSSION...
KEY MESSAGE 1...A cold front will pass through the region this
afternoon and evening.

Low pressure will pass through the region later this morning
and any lingering showers will taper off and move offshore.
Stratus and patchy fog will develop, and will gradually lift and
dissipate as the morning progresses as northwest winds increase
to near 10 mph by midday.

A cold front will approach later today and move across the
region this afternoon and evening. Surface dew points will rise
into the 70s today, and PWATs will be in excess of 2 inches.
SBCAPE values will increase to 1000 to 1500 J/kg as well with
high temperatures in the mid to upper 80s. Although there is the
potential for some brief, locally heavy rain, shear will be
limited and organized convection is not likely. PoPs will be
capped at chance.

Behind the cold front, high temperatures on Tuesday will be
similar to Monday, but dew points will drop from the low to mid
70s to the mid 60s. While warm, it should feel more comfortable
on Tuesday compared to Monday.


KEY MESSAGE 2...A cold front is expected to cross through the
region Wednesday night into Thursday resulting in more shower
and thunderstorm chances.

In the wake of Monday night`s cold front, weak high pressure
will briefly build into the region for Tuesday and much of
Wednesday. An upper-low will traverse portions of Ontario and
Quebec during this time, passing north of the region Wednesday
night. To the south of the upper-low, broad troughing will be in
place across much of the Northeast, with a few embedded
shortwaves pivoting around the base of the trough. At the
surface, a cold front will begin to approach the area late
Wednesday, and cross through the region Wednesday night into
Thursday.

Timing discrepancies remain with the frontal passage amongst
model guidance. Some guidance indicates the front passing
through the region primarily during the overnight hours
Wednesday night and clearing the region Thursday morning, while
there is still some guidance to suggest slower timing. At this
point, timing uncertainties limit confidence in whether or not
there will be any notable severe weather or flash flooding
concerns, but this will continue to bear watching, particularly
if the slower solutions come to fruition. For now, PoPs peak in
the 40-60% range across most of the area on Thursday.

There are also some indications that the pattern may remain
unsettled into the weekend as the front could get hung up just
south of the region with a couple of areas of low pressure
riding along it and mid-level troughing remaining in place. PoPs
are currently in the 20-40% range each day due to the present
uncertainties in timing and placement of these features.

In terms of temperatures, Tuesday and Wednesday look to be
fairly warm with modestly increasing humidity. Highs look to be
in the upper 80s to lower 90s. Temperatures currently look a bit
cooler in the wake of the front, with highs in the low to mid
80s and lows in the upper 50s to mid 60s late this week and into
the weekend.

&&

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

Today...Conds gradually lift to VFR by 18Z. A round of SHRA,
perhaps a TSRA, may pass across the terminals in the late
afternoon/early evening with brief sub-VFR conds. Will include
PROB30 groups to handle this potential. NW winds 5 to 10 kt.
Moderate confidence.

Tonight...Lingering SHRA possible through 06Z or so. Generally
VFR outside of any SHRA. N-NW winds 5 to 10 kt. Moderate
confidence.

Outlook...

Tuesday through Wednesday...VFR. No significant weather
expected.

Wednesday night through Friday...Periods of scattered showers
and perhaps storms are likely, with the greatest chance
currently appearing to be late Wednesday night into Thursday.
Sub-VFR conditions are possible with any showers or storms.

&&

.MARINE...
Wind gusts on Delaware Bay have diminished to less than 25 kt.
Therefore, the Small Craft Advisory is no longer in effect for
Delaware Bay. On the ocean, south winds continue to range from
15 to 20 kt with gusts up to 25 kt. Winds will turn west later
this morning and will diminish to 10 to 15 kt. Seas around 5
feet will subside to 2 to 4 feet as well. The SCA remains in
effect for the ocean until 11 am.

Sub-SCA conditions then expected for tonight.

VSBY restrictions in showers and isolated thunderstorms early
this morning. Another round of showers and thunderstorms
possible this afternoon and early evening.

Outlook...

Tuesday through Friday...No marine headlines currently
anticipated with winds under 25 kts and seas under 5 feet.
Scattered showers and perhaps storms could lead to periods of
visibility restrictions Wednesday night through Friday.

Rip Currents...

Today, southwest winds 15 to 20 mph with gusts up to 25 mph
this morning will turn west and diminish to 10 to 15 mph for the
afternoon. Breaking waves will average 1 to 2 feet. There will
be an increasing southerly swell with a 5 to 7 second period.
This results in a LOW risk for the development of dangerous and
life threatening rip currents for the Jersey Shore and Delaware
Beaches.

For Tuesday, north-northeast winds 5 to 10 mph in the morning
will gradually turn to be more southerly at 5 to 10 mph in the
afternoon. Breaking waves will average 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...Small Craft Advisory until 11 AM EDT this morning for
     ANZ450>455.

&&

$$

DISCUSSION...Cooper/DeSilva/Guzzo/Johnson/MPS
AVIATION...Cooper/DeSilva/Johnson/MPS
MARINE...Cooper/Guzzo/Johnson/MPS