412
FXUS61 KPHI 272032
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
432 PM EDT Sat Sep 27 2025

.SYNOPSIS...
A front settled south of the area will have a wave of low
pressure move along it and off to the northeast leading to
unsettled weather into Sunday morning. High pressure builds in
for the remainder of Sunday and into the beginning of next week.
Another cold front will pass through the area mid-week, followed
by a strong high pressure system building southward in its
wake.

&&

.NEAR TERM /THROUGH SUNDAY/...
Showers continue to move into the area through the remainder of
the day. This is due to a surface low that is moving off to the
northeast and looks to pass near or over Delmarva tonight.
There has not been much in the way of lightning associated with
this activity but an isolated thunderstorm is possible through
tonight.

Our main concern with this convection is any localized flooding.
PWAT values reach into the 1.5-2 inch range, especially as you head
south into Delmarva. There is also a solid warm cloud layer which
will help with warm rain processes. These showers or any
thunderstorms will be efficient rainfall producers. The best
coverage of the precipitation looks to be tonight with scattered
showers across the area with better coverage into Delmarva and parts
of southern New Jersey. Looking at the upper-levels, there looks to
be some signal of better forcing developing overnight in
southern New Jersey and into Delmarva which could help with more
localized enhancements of the precip.

In terms of rainfall totals through tomorrow morning, most
of the area looks to see 0.50 inches or less. However, localized
amounts of 1-2 inches are possible with any training heavier showers
or thunderstorms. The better potential for some of these localized
higher totals looks to be into Delmarva and Southern New Jersey
where precip coverage is better. Some models do show localized
totals of up to 3-4 inches in these areas but this appears to be
an outlier at this time. Flash flood guidance across the areas
where localized higher totals are possible is on the higher
side, so that is why this is more of an urban and localized
flooding concern. Due to this set-up, a slight risk (2/4) for
excessive rainfall is in place for the southern part of
Delmarva with a marginal risk (1/4) from Trenton southward.

We trend drier on Sunday with clouds decreasing from NW to SE as a
high pressure system builds in. Clouds will stick around a bit
longer for some of the coastal areas of southern New Jersey and
Delmarva. Highs on Sunday are in the upper 70s to mid 80s.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
High pressure just to our northwest will retreat slowly further
northwest as two tropical systems likely meander well to our
southeast. We should maintain enough high pressure control to keep
those systems away from us for the most part, but its not impossible
that a few showers make their way into our southernmost zones, and
clouds will definitely be more common across our southern zones
versus our northern ones. However, at least through Tuesday, clouds
and a stray shower should be the only notable impact locally. With a
relatively warm air mass in place and not likely to be dislodged
significantly, lows both nights should be in the upper 50s to mid
60s generally, with highs Monday upper 70s south to mid 80s north,
with more widespread upper 70s to near 80 on Tuesday due to greater
could cover.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
The combination of a strong cold front and lingering tropical
systems well off the coast will result in a fairly tight pressure
gradient starting Tuesday night and persisting for a few days. This
will result in breezy to windy conditions along the immediate coast,
with a gusty breeze reaching areas further inland as well, but not
nearly as strong. The cold front`s passage will also bring a much
cooler air mass to the region, likely the coolest so far this
season, with highs failing to reach 70 across the region by Thursday
despite fairly copious sunshine. The nights will also turn chilly,
with 50s and 60s Tuesday night being replaced by 40s and 50s
Wednesday night, and even some high 30s in the Poconos and NW NJ by
Thursday night. Wouldn`t rule out some frost by then, at least in
the colder spots. As a strong Canadian high builds southward and
overhead late in the week into early next weekend, winds relax and
temps start to moderate, with widespread low 70s likely for highs by
Saturday, and lows at least staying clear of the 30s by then. As
this will be a dry frontal passage followed by strong high pressure,
and the tropical systems are expected to remain far away overall, no
precip is expected through the period, but clouds may be present
especially over southern areas.

&&

.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas...

Rest of Today...VFR through 21Z-23Z. MVFR after 21Z-23Z due to
showers leading to visibility restrictions. Southeast winds at
5-10 knots. Moderate confidence.

Tonight...MVFR/IFR. NE winds around 5 kt. Ceilings lower to
sub-VFR and visibility restrictions continue due to showers.
Thunder was not included at any of the terminals due to low
confidence. KACY/KMIV/KILG/KPHL may see an isolated
thunderstorm (20% chance or less). Fog looks to develop after
06Z leading to low ceilings and visibility restrictions
continuing. Low confidence.

Sunday...MVFR/IFR conditions in the morning due to fog.
Conditions gradually improve after 14Z with ceilings lifting
and scattering out. Moderate confidence.

Outlook...

Sunday night through Thursday...VFR likely through the period.

&&

.MARINE...
Sub-Small Craft Advisory conditions through Sunday. East to
northeast winds 10 to 15 kt. Seas 2 to 3 feet.

Visibility restrictions in showers starting late this afternoon
over southern ocean waters, but the bulk of the activity will
occur tonight. An embedded thunderstorm or two are possible.

Outlook...

Sunday night through Monday...mainly sub-SCA with winds mostly below
20 kts and waves mostly below 5 feet.

Monday night through Thursday...Building waves and winds as tropical
systems well offshore bring fringe effects to our waters. Waves
likely exceed SCA levels starting Monday night, peaking Wednesday
then slowly diminishing starting Thursday. Wave heights may exceed
10 feet for a few days. Winds will be slower to ramp up but likely
exceed SCA levels by Tuesday night, and gales are possible
Tuesday night into Thursday, with the highest chance being
Wednesday.

Rip Currents...

For Sunday...Mainly northeasterly wind at 5-10 mph. Breaking
wave heights generally 1-2 feet. A southeasterly swell from
offshore storms starts to increase late in the afternoon.
Initially, our period is around 6 seconds but does start to
increase later in the afternoon with the potential for a longer
period swell developing at a period of around 10 seconds. Given
these factors, have opted to maintain a LOW risk for the
development of dangerous rip currents at all beaches at this
time.

For Monday, the increasing influence of longer period swells
around 13 to 16 seconds combined with there being multiple swell
groups will result in a MODERATE risk for the development of
dangerous rip currents at all beaches. Generally expect wave
heights in the surf zone to be around 2-3 feet.

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

&&

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

&&

$$

SYNOPSIS...Guzzo/Hoeflich
NEAR TERM...Guzzo
SHORT TERM...RCM
LONG TERM...RCM
AVIATION...Guzzo/RCM
MARINE...Fitzsimmons/Guzzo/Hoeflich/RCM