131
FXUS61 KPHI 031037
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
637 AM EDT Wed Sep 3 2025

.SYNOPSIS...
High pressure centered over the area today will gradually shift
eastward through Thursday. A pair of cold fronts will pass
through the area late this week- the first Thursday night or
Friday morning and the second, stronger front on Saturday. High
pressure to the west will build back into the region late this
weekend into early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Calm winds and mostly clear skies this morning may result in
some patchy shallow fog.

Surface high pressure remains outstretched across the
Appalachian range, leading to mainly fair weather with sunny
skies and overall dry conditions. That said, the broad upper
level troughing that has lingered across the eastern half of the
US for the past few days has triggered a few fair weather
clouds and a stray shower or sprinkle across the region. The
best chance for a spot shower or sprinkle will be in the
afternoon and early evening when some guidance shows a weak
shortwave pivoting across the Mid Atlantic, but any precip that
falls will be very spotty and insignificant. As a result, we can
expect more of the same for our Wednesday with afternoon highs
in the mid 70s to around 80. Nighttime lows will be in the low
50s to around 60.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
A closed upper-low will be meandering over portions of Ontario
Thursday morning. This feature will continue to move little
through the period, though it will finally start to advance
eastward slightly towards the Hudson Bay Friday night. At the
surface, high pressure centered to the northeast of the area off
the New England coast will lose its influence as a cold front
approaches the area Thursday night, and clears our area by
Friday morning.

While this first cold front will be undergoing frontolysis and
forcing for ascent will not be particularly strong, scattered
showers and a few thunderstorms are still expected beginning
Thursday evening and continuing through early Friday morning.
Given the more favorable environment and timing to the west of
our area, there will be a low risk for a couple severe storms
Thursday afternoon, which could reach western parts of our area
before weakening. As a result, the Storm Prediction Center has
placed western portions of our area in a Marginal Risk (1 of 5)
for severe storms. Locally heavy rainfall will be a possibility
especially across eastern PA and northern NJ where forcing will
likely be a bit stronger. However, for the most part, any
rainfall looks to be of the beneficial variety. In terms of
rainfall amounts, it currently appears that 0.5" or so is
possible across much of eastern PA, with amounts generally
0.25-0.5" across northern NJ into southeastern PA, and less than
0.25" across southern NJ and the Delmarva.

As previously stated, this cold front will be undergoing
frontolysis as it nears and eventually passes through the area,
and any reduction in temperature looks to be minor and short-
lived. Highs on Thursday look to be in the low-mid 80s for most,
with overnight lows in the low-mid 60s. Friday may actually be
the warmest the region has been in a while, with highs generally
in the mid 80s. Lows Friday night look to range from the low-
mid 60s across eastern PA and northern NJ to near 70 across the
Delmarva, southeastern PA, and southern NJ. While a few
lingering showers or an isolated thunderstorm cannot be ruled
out during the day Friday, it currently appears it will be
mostly dry.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
The upper-low across Ontario or the Hudson Bay to start
Saturday will track eastward into northern portions of Quebec
through Saturday night. South of the upper-low and embedded
within the larger scale eastern trough, a subtle shortwave axis
will shift east from the Great Lakes and eventually across New
England. While this shortwave looks to pass to the north of the
area, once again limiting large-scale forcing for ascent, a
stronger cold front will move through the region Saturday
evening and into Saturday night.

Ahead of this cold front, at least modest instability will be
present. Scattered showers and thunderstorms are once again
expected Saturday afternoon into Saturday night. The trend in
model guidance has been for increased areal coverage of storms,
and a bit more instability. At least a low-end severe threat
could ultimately evolve, but confidence is low, so for now this
will just be something to monitor as it gets closer in time.

Ahead of the cold front Saturday, another warm day is expected,
with highs generally in the mid-upper 80s. Behind the cold
front Saturday night, temperatures will be noticeably cooler,
with the low-mid 50s currently expected across eastern PA and
northern NJ, and the upper 50s to near 60 elsewhere.

Sunday, as the upper-low continues to track eastward well to
the north of the area, and the cold front pushes farther
offshore, the primary trough axis will shift eastward through
portions of Ontario, Quebec, and into New England. Broad ascent
associated with this feature will continue to overspread the
area Sunday, and because of this a few showers cannot be ruled
out. However, given the cooler and drier post-frontal airmass,
most of the area should be dry. In addition, high pressure over
the Midwest will be building into our region Sunday night into
Monday. Any isolated showers will likely come to an end by
Sunday night, with dry conditions areawide Monday. Afternoon
highs both days look to be in the mid 70s, with lows ranging
from the upper 40s to lower 50s.

The high pressure over the area should begin to shift northeast
on Tuesday. There have been some hints in model guidance of
unsettled weather returning around this time, but given that
there is not much model agreement and it is day 7, will stick
with the NBM, which has Tuesday remaining dry. Similar
temperatures to Sunday and Monday are expected.

&&

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

Wednesday...Lingering shallow patchy fog this morning, mainly at
ACY/MIV. Otherwise, VFR with a FEW/SCT afternoon clouds. East
winds in the morning, becoming south winds around 5 kt in the
afternoon. Moderate confidence.

Wednesday night...Prevailing VFR. Light and variable winds.
High confidence.

Outlook...

Thursday...Primarily VFR. Brief periods of sub-VFR conditions
are possible in scattered showers and a few storms late.

Thursday night...Sub-VFR conditions possible in scattered
showers and a few embedded storms.

Friday through Friday night...Primarily VFR. An isolated shower
or storm cannot be ruled out.

Saturday through Saturday night...Sub-VFR conditions are
possible in scattered showers and storms Saturday afternoon
through Saturday night.

Sunday...Primarily VFR. An isolated shower cannot be ruled out.

&&

.MARINE...
Winds and seas are expected to be below Small Craft Advisory
Criteria through Wednesday night. NNE winds early this morning
around 5-10 kts will turn SSE in the afternoon. Southerly winds
10 kts or less prevail overnight. Seas around 3 feet.

Outlook...

Thursday through Saturday night... Southerly winds may be
elevated through much of the period with winds potentially
nearing or exceeding 25 kt at times. Wave heights also look to
increase, particularly on Friday. Marine headlines could be
needed for at least part of this timeframe.

Sunday... Winds and seas look to decrease significantly. No
marine headlines expected.

Rip Currents...

Today...Northeasterly wind 10 mph will become east-
southeasterly in the afternoon. Breaking wave heights 2 to 3
feet, with a dominant period of 8 to 10 seconds, though there
are multiple wave groups present. Given the forecast trend of
wind being more onshore, have opted for a MODERATE risk for the
development of dangerous rip currents at all beaches.

Thursday...Winds become more southerly and increase to 10-15
mph by the afternoon. The dominant period should start off as 7
to 10 seconds, but shorter period wind waves (4 to 5 seconds) is
expected to be the dominant wave group by the late afternoon.
Breaking wave heights are forecasted to be 2-3 feet. Given these
forecast conditions a MODERATE risk for the development of
dangerous rip currents at all beaches is expected.

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/Johnson/MJL