441
FXUS61 KPHI 011025
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
625 AM EDT Mon Sep 1 2025

.SYNOPSIS...
High pressure will remain in place across the Northeastern US
through Wednesday. The high will become displaced to the east of
the area Thursday. A series of cold fronts will bring a more
unsettled pattern late Thursday into the weekend. High pressure
will once again become established across the area late this
weekend into early next week.

&&

.NEAR TERM /THROUGH TUESDAY/...
Cool weather continues as we usher in the first day of
meteorological fall! With broad surface high pressure across
southern Quebec, the resultant northeast flow across the region
will keep temperatures several degrees below average for early
September. Afternoon highs will be in the mid to upper 70s and
overnight lows will be 50s. Scattered to broken clouds will be
around, but no precipitation is expected.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
A relatively weak, but closed trough centered over portions of
the Northeast will continue to shift northeastward through the
period. Meanwhile, a strong upper-low will dive southeastward
across portions of Manitoba and Ontario, and eventually into the
Northern Great Lakes. At the surface, high pressure initially
encompassing the Northeast will shift slowly eastward, though it
should maintain influence over local weather through Wednesday
night.

Pleasant and dry weather should continue through this
timeframe, with a slight warming trend. Lows Tuesday night will
be in the mid 50s. On Wednesday, temperatures will be near 80
for most locations, with overnight lows ranging from the mid 50s
to low 60s.

One thing to note is that light southerly flow will return to
our area Tuesday night and continue through Wednesday night. As
a result, moisture will be on the increase. Coincident with this
increase in moisture, clouds will also generally be on the
increase. In addition, areas of fog could become a concern both
Tuesday night and Wednesday night, so this will need to be
monitored going forward.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
The aforementioned strong upper-low located over the Northern
Great Lakes Thursday morning will likely begin undergoing an
occlusion process with its associated surface cyclone, and
meander over portions of Ontario through Friday night, before
beginning to move eastward again across portions of Quebec
through the weekend. Height falls and enhanced mid- and upper-
level flow will overspread the region beginning Thursday
afternoon. At the surface, high pressure will continue to slide
east into the Atlantic and lose influence over the area. A cold
front will pass through the region on Friday, with another
stronger front moving through on Saturday.

The daytime hours on Thursday should be dry for most, with
highs in the low 80s. Rain chances may begin to increase across
portions of eastern PA during the evening hours. Thursday night
into Friday will feature rain chances areawide. PoPs look to be
of the chance variety across southern NJ and the Delmarva, but
likely (60%+) for eastern PA and northern NJ. It currently
appears that there will be at least some instability ahead of
the cold front, so some of this activity could be in the form of
thunderstorms. However, severe weather currently appears
unlikely. Model guidance suggests PWATs will be 1.5"-1.75", so
locally heavy rainfall will certainly be possible. However,
overall rainfall amounts should be light enough to minimize
flooding concerns. Low temperatures Thursday night look to be in
the low-mid 60s, and high temperatures Friday in the upper 70s.
While timing at this range is still fairly uncertain, it
appears this first cold front and associated rain chances will
clear the area by Friday afternoon. Friday night`s temperatures
should be a bit cooler than previous days, ranging from the mid
50s to lower 60s.

Ahead of the cold front on Saturday, high temperatures will
range from the upper 70s to lower 80s. While the highest rain
chances should be with the front on Friday, a few showers and
thunderstorms will also be possible on Saturday ahead of the
stronger cold front. Once Saturday`s cold front clears the area,
high pressure will begin to build back in from the northwest,
bringing a return to dry and cooler weather. Highs on Sunday and
Monday currently look to be in the mid 70s, with lows in the
low-mid 50s.

&&

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

Rest of tonight...VFR conditions continue. Winds around 5 knots
or less, favoring the northeast. Light and variable most places
overnight. High confidence.

Monday...VFR conditions expected. Northeast to east winds 5-10
knots increase to 10-15 knots with gusts 15-20 knots through the
day. High confidence.

Monday night...VFR conditions. North to northeast winds around
5-10 knots become light and variable overnight. High confidence.

Outlook...

Tuesday through Thursday...Primarily VFR. Sub-VFR conditions
are possible in low clouds or areas of fog primarily Tuesday
night and Wednesday night.

Thursday night through Friday...Sub-VFR conditions are possible
in scattered showers and perhaps a few thunderstorms.

&&

.MARINE...
Conditions are expected to remain below advisory criteria.
Northeast winds around 15-20 kts with seas largely 3 to 4 feet.
Could see occasional 5 foot waves further offshore, but
confidence is not high enough to issue an SCA.

Outlook...

Tuesday through Friday...Northeasterly wind on Tuesday
generally 15- 20 kt with seas around 4 feet. While an SCA is not
currently anticipated, conditions will continue to be monitored
for an increase in forecasted winds or seas. Winds and seas
should subside further Tuesday night through Wednesday night.
Another increase in winds and seas is possible Thursday into
Friday.

Rip Currents...

Today...Northeasterly wind around 15 mph. Breaking wave heights
2 to 3 feet, with a 6-8 second period. Will maintain the
MODERATE risk for the development of dangerous rip currents at
all beaches.

Tuesday...Northeasterly wind 10 mph will become east-
northeasterly in the afternoon. Breaking wave heights 2 to 3
feet, with a 7-9 second period. Given the forecast trend of wind
being more onshore, have opted to introduce a MODERATE risk for
the development of dangerous rip currents at all beaches.

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

&&

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

&&

$$

SYNOPSIS...Cooper
NEAR TERM...MJL
SHORT TERM...Cooper
LONG TERM...Cooper
AVIATION...Cooper/MJL
MARINE...Cooper/MJL