557
FXUS61 KPHI 221100
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
700 AM EDT Tue Jul 22 2025

.SYNOPSIS...
High pressure will build out across the northeast states on
Tuesday, then shift offshore Tuesday night into Wednesday. This
high will shift farther out to sea through Thursday and Thursday
night and will provide fair weather through Thursday. A cold
front will approach later Friday and stall near the area through
the weekend, bringing unsettled weather to the area Friday
through Sunday.

&&

.NEAR TERM /THROUGH TONIGHT/...
Some changes to the forecast for this afternoon. High pressure
over the eastern Great Lakes moves into northern New York state
later today, then slides towards the Gulf of Maine tonight.
Meanwhile, an H5 trough lies over the Northeast, and some
shortwave energy dive into the base of the trough this
afternoon. This is where things get a bit interesting.

Quiet conditions through this morning. As high pressure builds
east, winds will take on an easterly flow over New Jersey and
into southern Delaware, while winds will be a bit more northerly
west of the I-95 corridor. A boundary sets up in this area,
aided by afternoon sea breezes. As that aforementioned shortwave
approaches from the west, it will interact with that boundary
to trigger some widely scattered afternoon showers, mainly over
eastern New Jersey and far southern Delaware. While not
overwhelming, there will be some instability over New Jersey
with up to 300 J/kg of surface-based CAPE. Latest NAMNEST BUFKIT
profiles for eastern New Jersey showing an inverted-V pattern
up to about 950 mb. 00Z/22 NAM, 00Z/22 GFS, and the latest CAMS,
including the 00Z/22 HRRR showing at least spotty showers,
though the NAM may be a bit high on QPF. Latest NBM is dry, so
will go ahead and add 20-30 PoPs for New Jersey and southern
Delaware. These instability showers will be diurnally drive, so
expect any showers to taper off by/around sunset. Important to
note that it will be dry, and even pleasant, most everywhere
across the forecast area and any showers will be highly
localized.

While dew points should still mostly be in the 50s west of the
I-95 corridor, onshore flow will result in dew points well in
the 60s east of I-95. Highs today will be several degrees below
normal, mainly in the lower 80s.

Tonight, skies will be clear with nearly calm winds. There will
be a slight onshore component to the winds, allowing for low
level moisture to increase over the region. Dew points will be
creeping up throughout, generally into the lower 60s west of the
I-95 corridor and in the mid and upper 60s east of the I-95
corridor. There is the potential for some patchy fog and/or some
stratus to develop. Lows tonight will be in the 60s.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
Seasonable weather conditions expected through the middle of
the week. High pressure will be shifting offshore by Wednesday
where it will remain through the end of the week. Southwest
return flow will ramp up into Thursday. Fair and dry weather is
expected, although there could be an increase in cloud cover
Wednesday due to onshore flow. Temperatures and humidity begin
to rebound Wednesday and continue to increase into Thursday as
return flow fully sets up across the area. Highs in the mid 80s
for most on Wednesday, and closer to 90 degrees by Thursday.
Lows in the 60s Wednesday night into Thursday morning, and near
70 degrees Thursday night into Friday morning.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
The end of the week and weekend period will be very warm to hot
and humid, with mostly unsettled (showery and stormy)
conditions.

By Friday, with return flow fully in place ahead of an
approaching cold front, temperatures and humidity values will
continue to increase as thicknesses increase across the area.
Heat Index values are forecast to be high enough (near 100-105
degrees possible) for potential Heat Headlines. As a cold front
approaches, there could be enough instability and disturbances
aloft for showers and thunderstorms to develop later in the day
and into the evening hours.

This front may stall near the area over the weekend, leading to
additional showers and thunderstorms Saturday into Sunday.
Also, depending on where the front sets up, areas south of the
boundary may keep enough heat and humidity in place for
additional Heat Headlines on Saturday, although we should be
safe from any Heat Headlines by Sunday. With PW values near 2+
inches, heavy rainfall will become a threat with any showers or
thunderstorms. There may also be a threat for strong winds as
well with some storms.

By Monday, the front will likely begin to shift southward,
which should bring an end to the more widespread showers and
thunderstorms. However, there could still remain a few isolated
showers or storms around due to some lingering moisture and
possible disturbances aloft.

&&

.AVIATION /11Z TUESDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Today...VFR. NE winds 5 to 10 kt, becoming LGT/VRB after 18Z,
then turning E-SE. A spotty SHRA may impact KMIV/KACY in the
afternoon, but not expecting restrictions. Moderate confidence.

Tonight...Generally VFR, but cannot rule out spotty sub-VFR
conditions in BR/stratus. Nearly calm winds. Low confidence.

Outlook...

Wednesday-Thursday night...Mostly VFR conditions expected. Some
patchy light fog or low clouds are possible each night and
toward daybreak, especially at MIV/ACY.

Friday-Saturday...Generally VFR. Chance of showers and
thunderstorms which could temporarily lead to lower conditions.

&&

.MARINE...
Sub-Small Craft Advisory conditions today and tonight. NE winds
10 to 15 kt with occasional gusts to 20 kt will turn E later
today. E to SE winds 5 to 10 kt tonight. Seas 2 to 3 feet.

A spotty shower this afternoon may result in a brief wind gust
to 30 kt.

Outlook...

Wednesday-Saturday...Conditions remain below advisory levels,
although winds could approach 20 knots later Thursday through
Friday. There is also a chance of showers and thunderstorms
Friday into Saturday, which may lead to locally higher winds and
waves.

Rip Currents...

Today, northeast winds at 5 to 10 mph will become east by this
afternoon, then southeast late. Breaking waves will average
around 2 feet with a period of 5-8 seconds. As a result, there
is a LOW risk for the development of dangerous rip currents at
the Jersey Shore and the Delaware Beaches. Widely scattered
showers are possible this afternoon.

On Wednesday, east to southeast winds will be around 10 mph.
Breaking waves will average again around 2 feet, however the
period may length some to 7-10 seconds. As a result, there is a
LOW risk for the development of dangerous rip currents for both
the Jersey Shore and the Delaware Beaches.

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

&&

.TIDES/COASTAL FLOODING...
Onshore flow will occur through Wednesday. A new moon is coming
up on Thursday, July 24th. As a result, tides will creep up
over the next several days. Some minor tidal flooding looks to
occur with the higher of the two tides across southern New
Jersey, Delaware, the Delaware Bay, and the tidal portion of the
Delaware River. High tides across central and northern New
Jersey will also inch up the next few days. But at this time, it
appears they will fall just short of minor flooding levels.

&&

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

&&

$$

SYNOPSIS...Robertson/Staarmann
NEAR TERM...MPS
SHORT TERM...Robertson/Staarmann
LONG TERM...Robertson/Staarmann
AVIATION...MPS/Staarmann
MARINE...MPS/Staarmann
TIDES/COASTAL FLOODING...