Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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513
FXUS61 KPHI 161830
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
230 PM EDT Sat Aug 16 2025

.SYNOPSIS...
High pressure centered near the Canadian Maritimes will move
offshore Saturday night into Sunday. A cold front passes through
the region Sunday night then becomes stationary over the Mid-
Atlantic into the new week. High pressure builds in from the
north through the middle to end of next week as Hurricane Erin
passes by well offshore.

&&

.NEAR TERM /THROUGH SUNDAY/...
A surface trough to our west is providing a focus for isolated
showers and storms to develop this afternoon. It is possible
that a few showers and storms could work their way into our
region. We have even seen isolated showers develop in the Pine
Barrens, likely along a differential heating boundary where we
saw clouds clearing earlier today. Some of the storms to our
west have been very slow moving and efficient rain producers,
so will keep a close eye on radar trends through the afternoon.
Expect this activity to diminish quickly with sunset.

Overnight, there is a small chance (less than 20%) for fog to
develop. However, complicating this potential is the fact that
mid level clouds may advect into the region as the high shifts
further east which would limit fog development. For now have
left a mention out of the forecast given the low probability of
occurrence.

On Sunday, the surface high will continue to shift east and a
cold front is expected to trail closely behind. At this point,
it appears as if the front won`t arrive during the day, rather
Sunday night. However, this will still have two consequences for
the weather during the day tomorrow. First, tomorrow is expected
to be a few degrees warmer than what we saw on Saturday. Second,
another round of showers and storms is possible as a weak pre-
frontal trough over our region in the afternoon could serve as a
focus for convective development. At this point, the main
concern with any storms tomorrow will be heavy rain.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
As the cold front passes through Sunday evening, we can expect
a few scattered showers and thunderstorms. Overall baroclinic
forcing looks weak with unimpressive lapse rates, thus coverage
at this point still looks limited. POPs remain in the 20-35%
range with limited severe and flash flooding potential. High
pressure builds in behind the Sunday night, pushing any showers
or storms out to sea and allowing drier air to filter in.
Overnight lows will be in the 60s to around 70.

High pressure building in from the north and east will lead to
persistent onshore flow Monday and Tuesday. As a result, a
cooler airmass will be in place allowing high temps Monday
afternoon to only reach the mid 70s to low 80s with similar
temperatures expected Tuesday. With the frontal boundary
lingering just south of the area, this will keep the chances for
some light showers around for both Monday and Tuesday but POPs
are only around 20 to 30 percent.

&&

.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
A frontal boundary will continue to linger nearby Tuesday night
through Wednesday and as some shortwave energy moves in from the
west, this will bring an increasing chance for some showers and
possibly a few embedded thunderstorms. Temperatures will remain
on the cool side of climo.

The other main story will be Hurricane Erin which is currently
located east of the northern Leeward Islands. It is expected to
track well offshore to the east of the area later Wednesday into
Wednesday night but we`ll still likely have some indirect
impacts from it. Potential impacts include a high risk for rip
currents, rough surf, and the potential for minor coastal
flooding beginning as early as Monday and lasting into Thursday.
Please refer to the National Hurricane Center for more details
and stay tuned to the local forecast.

High pressure should bring fair and dry weather for the end of the
week.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Through Tonight...Prevailing VFR conditions expected. There is a
small chance (20% or less) for another round of low clouds
and/or fog. However, few models depict this, and any mid level
clouds overnight could limit fog or low stratus development.
Thus, for now, have not included this potential in the TAFs. IF
it were to happen, the period of highest risk would be between
09 and 12Z. Winds generally out of the SE or SW.

Sunday...Prevailing VFR. There is a 20 - 30% chance of afternoon
storms for KABE and KRDG, which could result in temporary MVFR
conditions. However, coverage is expected to be very limited, so
low confidence if the terminals would be directly impacted.
Winds mostly light (less than 10 kt) out of the southwest, but
an afternoon sea breeze could get as far inland as KACY and KMIV
shifting winds to SSE.

Outlook...

Sunday night through Monday...A period of MVFR cigs may develop
due to low stratus.

Tuesday through Wednesday...Mainly VFR with periods of sub-VFR
conditions possible from showers and thunderstorms.

&&

.MARINE...
Winds and seas will stay below Small Craft Advisory conditions
through Sunday.

Outlook...

Monday...SCA conditions with the passage of a frontal boundary.
Winds turn northeast with gusts around 20-25 kts with seas
building to 5-7 feet.

Tuesday through Thursday...SCA conditions continue due to the
approach of what is currently Hurricane Erin. Elevated winds and
seas develop Tuesday and will last into at least Thursday. Seas
5-7 feet Tuesday build as high as 8-12 feet by Thursday.

Rip currents...
Buoy observations indicate an underlying long period (15 sec)
swell that is not being modeled well. This, combined with a
light onshore flow, would suggest a MODERATE risk for the
formation of dangerous rip currents, even though the waves are
only 1 to 2 feet.

For Sunday, southerly winds around 10-15 mph, breaking wave
heights around 1-2 feet, and a light easterly swell around 4-5
seconds. As a result, have opted to continue with a LOW risk for
rip currents for all beaches on Sunday. However, will need to
continue to monitor trends with the long period swell that was
observed Saturday morning.

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

&&

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

&&

$$

SYNOPSIS...Fitzsimmons/Franklin/MJL
NEAR TERM...Johnson
SHORT TERM...Fitzsimmons/MJL
LONG TERM...Fitzsimmons/MJL
AVIATION...Johnson/MJL
MARINE...Johnson/MJL