165
FXUS61 KPHI 031851
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
251 PM EDT Wed Sep 3 2025

.SYNOPSIS...
High pressure centered over our region will gradually shift eastward
through Thursday. A weakening cold front moves through our area
later Thursday night and Friday morning, followed by a stronger cold
front during Saturday and Saturday night. High pressure then builds
in for Sunday through early next week.

&&

.NEAR TERM /THROUGH THURSDAY NIGHT/...
High pressure is more dominant today as the upper trough
previously over the area has lifted north. Thus, despite plenty
of clouds at times, so far no rain has occurred in the region
today. Think this most likely continues, though just enough
instability could be enough to cause a stray shower. Unlike
yesterday, the most likely locale today appears to be in the
Poconos, but confidence like yesterday is quite low.

Overnight, clear to partly cloudy skies will predominate. With a
bit of an increase in southerly flow as the high pressure
slides east and a front start to approach from the northwest,
may not have as much of a risk of patchy fog, but can`t
completely rule it out. Lows should stay a little milder than
last night, but still mostly in the 50s.

Southwest flow will be notably stronger on Thursday, especially
in the afternoon, as the aforementioned front creeps ever closer
from the northwest. Thus, we`ll have a gusty southwest breeze by
afternoon along with a temp spike into the low-mid 80s for most.
Right now however, it looks like most if not all shower/t-storm
potential holds off until at least early evening.

Front arrives Thursday night, with best chance of showers-storms
in the evening. That said, with arrival for much of the area
near/after sunset, instability will already be waning, so
showers/storms likely start weakening before arrival. Still,
there remains a marginal severe weather risk across part of the
region. Could also be some locally heavy downpours, but right
now most of the region would look upon this as a beneficial
rain, even though it is most likely confined to areas north and
west of I-95. Lows stay mild with the southerly flow and clouds,
with most spots failing to drop below 60.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
A warm and much more humid air mass in place as two cold fronts work
their way across our area. The first front shifting to our east
Friday is weak (little or no temperature changes). The second front
later Saturday is stronger.

A closed low is forecast to be centered near Hudson Bay Canada
Friday before gradually weakening and shifting eastward through
Saturday. An initial surface low tracks well into Canada Friday,
however its associated cold front will be crossing our area with it
weakening even further (a lack of a thermal gradient with it). While
an isolated shower or thunderstorm cannot be ruled out especially
Friday afternoon and/or evening, the lack of focused forcing for
ascent should result in most places remaining rain-free. It will be
a warm and more humid day with no push of cooler and drier air with
this weakening front. High temperatures are forecast to be in the
mid to upper 80s for much of the area Friday afternoon. The higher
dew points will also keep it much milder Friday night.

As we go through Saturday, the closed low looks to weaken as it
gradually shifts east from Hudson Bay Canada. Its trough axis
however stretches back across the Great Lakes and toward the Mid-
Mississippi Valley. This slowly shifts eastward through Saturday
night. A stronger cold front associated with this trough is forecast
to cross our area Saturday afternoon and Saturday evening. While the
trough axis is forecast to remain displaced to our northwest and
west, a belt of stronger mid level flow is forecast to overspread
our area during Saturday. The model guidance differs with the amount
of instability that occurs, probably due to weaker mid level lapse
rates and timing of the front, therefore the coverage and intensity
of the convection is a bit more in question. Some showers and
thunderstorms however are expected to occur ahead of and with the
cold front, and with some increase in the mid level flow some
convection could organize into line segments and/or clusters. If
some convection is able to organize/be sustained and occurs during
peak heating, there is some potential for locally strong/damaging
winds given the moisture content and potentially favorable DCAPE
values. It will be a warm and humid day with highs above average. As
the front shifts eastward, drier and cooler air will start to arrive
from the west during Saturday night along with decreasing chances
for convection.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Summary...Mainly below average temperatures along with mostly dry
conditions.

Synoptic Overview...A weakening upper-level trough axis is forecast
to pivot across much of the East Sunday into Monday, then a
secondary upper-level trough axis arrives closer to midweek. At the
surface, a sprawling area of high pressure is forecast to build
across our area through early next week. The high then shifts to our
northeast and east during Tuesday and Wednesday. A disturbance may
develop along a stalled front off the Southeast U.S. in the Tuesday
to Wednesday time frame.

For Sunday and Monday...As an upper-level trough axis swings across
much of the East Sunday into Monday it may weaken some. A fairly
expansive area of surface high pressure across the Great Lakes to
the Ohio Valley is forecast to build eastward during this time. A
much drier air mass is forecast to be in place across our area along
with cool temperatures, however with the trough axis aloft sliding
through the colder air aloft should result in some diurnally
enhanced cumulus development. While a few sprinkles or brief showers
cannot be ruled out from these clouds on Sunday, the dry air below
cloud base should limit this. Given the initial trough axis
weakening and shifting to our northeast Monday, afternoon high
temperatures may be a bit higher although still below average.

For Tuesday and Wednesday...The model consensus of the upper air
pattern favors surface high pressure shifting to our northeast and
east. There is still a trough axis aloft over or near our region and
this may extend down into the northeast Gulf. A stalled surface
front off the Southeast U.S. coast may provide some focus for a
disturbance to develop along it. This may get a boost from some
shortwave energy associated with the weak trough aloft. There is
increased uncertainty with the development of this disturbance not
only if/where it develops but also its future track. Something to
keep an eye on as some guidance suggest it makes a run northward and
brings some rain to our area. Another scenario is that the
aformentioned surface high acts as a block and keeps the disturbance
well to our south. Based on the uncertainty and this being days 6
and 7, ran with the National Blend of Models (NBM) guidance.

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Thru 0Z...VFR with SCT clouds. South winds around 5 kt.
Moderate confidence.

Tonight...Prevailing VFR. Light and variable winds favoring a
southeast or south direction. High confidence.

Thursday...VFR with SCT clouds. Any showers/t-storms likely hold
off until evening. Winds increasing from the south southwest
with gusts up to 25 kts during the afternoon. Moderate
confidence.

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

Outlook...

Friday...Mostly VFR. An isolated shower or thunderstorm cannot be
ruled out.

Saturday...Some showers and thunderstorms, especially in the
afternoon and at night, with times of sub-VFR conditions.

Sunday and Monday...VFR.

&&

.MARINE...
Winds and seas are expected to be below Small Craft Advisory
Criteria through tonight. SSE winds 5-10 kts. Seas around 3
feet.

For Thursday into Thursday night, increasing southerly flow
ahead of an approaching cold front may result in low-end Small
Craft Advisory conditions, with winds gusting to 25 kts or so by
late in the day and at night, along with seas possibly reaching
5 feet. A few showers and thunderstorms may also pass across the
waters at night.

Outlook...

Friday and Saturday...Southerly wind gusts to around 20 knots. Seas
within some of the ocean zones may touch 5 feet for a time.
Otherwise, the conditions should be below Small Craft Advisory
criteria. A few thunderstorms late Saturday afternoon and evening
could produce locally gusty winds.

Sunday and Monday...The conditions are anticipated to be below Small
Craft Advisory criteria.

Rip Currents...

This afternoon...East-southeast winds around 10 mph. 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...Gorse
NEAR TERM...RCM
SHORT TERM...Gorse
LONG TERM...Gorse
AVIATION...Gorse/RCM
MARINE...Gorse/Johnson/RCM