592
FXUS61 KPHI 180921
AFDPHI

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

.WHAT HAS CHANGED...
Increasing chances for showers and thunderstorms on Thursday.
Otherwise, no significant changes to the forecast.

&&

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

2. Another cold front is expected to cross through the region
on Thursday, resulting in greater chances for showers and
thunderstorms. Likely remaining unsettled through the weekend,
with daily chances of showers and storms each afternoon and
evening.

&&

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

An isolated shower or rumble of thunder will remain possible
overnight, but no significant weather is expected.

A weak cold front will gradually sink south today into tonight.
Behind the cold front, temperatures and dewpoints will only
fall slightly. There may be areas of patchy fog in rural
locations, especially where any evening showers took place.
High temperatures today will be just about identical to Monday,
but dewpoints will drop some with mainly lower and middle 60s
further north, and upper 60s to around 70 well south. While
warm, it should feel more comfortable compared to Monday.

Th main story today will be the potential for some diurnally
driven isolated showers and storms developing this afternoon.
These will be focused along and south of the front, with greater
coverage of convection more probable along and southeast of
I-95. Aside from lightning, no hazardous weather is anticipated
with this activity.

Any convection will diminish after sunset, then dry overnight
with patchy fog possible again. Dry and seasonable Wednesday
with lower humidity, though highs will still be in the mid to
upper 80s.


KEY MESSAGE 2...Another cold front is expected to cross through
the region on Thursday, resulting in greater chances for
showers and thunderstorms. Likely remaining unsettled through
the weekend, with daily chances of showers and storms each
afternoon and evening.

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 late Wednesday night into early Thursday.

Timing discrepancies remain with the frontal passage among the
model guidance, though a slower trend has begun. 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 some guidance suggesting 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 be monitored
in subsequent forecast cycles. If slower solutions come to
fruition then the chances of impacts from heavy rain would
increase. PoPs have increased for the area on Thursday,
especially along and southeast of I-95, but much of the region
now has 60-80% PoPs for Thursday afternoon and evening.

Longer range NWP and AI guidance suggests that the pattern
remains unsettled later Friday and into the weekend. The frontal
boundary could get hung up just south or even over the area
with multiple areas of weak low pressure riding along and mid-
level troughing remaining in place. 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. At this time PoPs for this
period are relatively higher further south and east.

In terms of temps, highs will be mainly in the upper 70s to mid
80s through the weekend and lows in the upper 50s to mid 60s
late this week and into the weekend. Part of the reason for this
will be due to more cloud cover, and humidity will increase.

&&

.AVIATION /09Z TUESDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Through 12Z...Generally MVFR to IFR ceilings developing for most
areas outside of RDG/ABE, where confidence in restrictions is
lower. Variable winds favoring a northerly direction less than 5
kts. Moderate confidence.

Today...Restrictions from low ceilings early, then scattering
out to VFR by 16Z. Isolated SHRA/TSRA possible (10-20% chance),
but coverage is too low to warrant a TAF mention at this time.
North winds shifting northwest around 5-10 kts. High confidence
in prevailing VFR following restrictions early, low confidence
on timing of improvements.

Tonight...VFR early, though some patchy fog may develop after
04Z. Northwest winds around 5 kts or less. Low confidence on any
fog restrictions.

Outlook...

Wednesday...VFR. No significant weather expected.

Wednesday night through Friday...Periods of scattered showers
and perhaps storms are likely, with the greatest chance and
coverage on Thursday. Restrictions are possible with any
showers or storms.

&&

.MARINE...
No prevailing marine hazards expected. Isolated showers or
storms with locally gusty winds and higher seas possible through
this evening.

Outlook...

Wednesday through Friday...No prevailing marine hazards
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
Thursday. Scattered showers and storms are likely again late
Friday into Saturday.

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...Staarmann
AVIATION...Staarmann
MARINE...Staarmann