046
FXUS61 KPHI 010725
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
325 AM EDT Mon Jul 1 2024

.SYNOPSIS...
High pressure builds in later today through Tuesday before
moving offshore Wednesday. A surface trough arrives on Thursday
as a cold front may approach from the northwest Friday into the
weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
A significant air mass change is occurring in the wake of a
cold front, therefore it will be much cooler with much lowered
dew points/humidity through tonight.

Across our lower Delmarva zones to the Cape May County area, a few
showers will occur early this morning before much drier air takes
over as the cold front settles south and east.

The axis of an upper-level trough is forecast to cross our area
through about early this afternoon. As this occurs, the center of
high pressure across the Great Lakes and upper Ohio Valley gradually
builds eastward. This will result in a northerly wind today, and
there is a tightened pressure gradient across our area. This is the
most pronounced through about early afternoon, therefore with deeper
mixing with heating through the morning enhanced some by cold air
advection, a notable northerly breeze will be present today. This
should start to diminish some by later in the afternoon as the
pressure gradient starts to weaken as high pressure draws closer.
Given the colder air aloft, cyclonic flow for a while and the
passage of the trough axis, some stratocumulus is expected to be
around. The forecast soundings show enough moisture at the top of
the boundary layer to promote some of these clouds. Given the
presence of the trough axis crossing our area through early
afternoon, there could be a period of more cloud cover than
currently forecast. Some of the stratocumulus is already sliding
southward from the Pocono region as it becomes trapped beneath a
strengthening subsidence inversion. High temperatures are forecast
to be below average for this time of the year, and with dew points
down into the 50s and a breeze it will feel significantly cooler
today.

Any stratocumulus dissipates into this evening as high pressure
continues to get closer and even drier air pushes in. The winds are
forecast to pretty much decouple in most places during the evening
into the overnight. This combined with a clear sky and a much drier
air mass will result in lows in the 50s late tonight for much of the
region (some lower 60s in the urban centers and along the
coast).

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
High pressure will remain the dominant feature through Wednesday.
The mostly pleasant and tranquil conditions will continue
Tuesday and Wednesday. Highs on Tuesday will be near normal,
mainly in the low-mid 80s. However, with dew points forecast to
remain in the 50s, another pleasant day looks to be on tap.
Lows Tuesday night will be a touch warmer as well, mainly in the
low-mid 60s.

As the high shifts further east on Wednesday, expect low level
southerly return flow to usher in a modest warming trend, but
conditions should remain quite pleasant.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Summary...Approaching trough and cold front will be responsible
for rain chances through the long term. Few changes from the
previous forecast.

Synoptic Overview...A Canadian upper-level trough will push the
ridge southward some Thursday and Friday. At the surface, a
trough arrives Thursday with a cold front approaching from the
northwest Friday.

Thursday (Independence Day) through Sunday...Southerly flow
becomes more established leading to hot and humid conditions
through the weekend. The influence of a Canadian upper-level
trough will start to approach during Thursday, however the
timing and amplitude of this trough is less certain. As of now,
the main trough is more toward the Midwest and therefore the
associated cold front may be slow to approach our area late in
the week. There may be a pre- frontal trough in our vicinity
Thursday into Friday and this may provide enough focus amid a
destabilizing air mass to initiate some convection.

&&

.AVIATION /08Z MONDAY THROUGH FRIDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Today...VFR. North-northwest winds 10-15 knots with gusts up to 25
knots, diminishing by later this afternoon. Moderate confidence.

Tonight...VFR. Northerly winds 5-10 knots, becoming light and
variable at many of the terminals. High confidence.

Outlook...

Tuesday and Wednesday...VFR with no significant weather.

Thursday and Friday...Sub-VFR conditions possible with chances
(25-35%) for SHRA and TSRA, especially in the afternoon.

&&

.MARINE...
A northerly wind will be in place today and with cold air advection
occuring within a tightened pressure gradient, mixing is expected to
be sufficient for gusts of 25-30 knots. A northerly wind surge is
occurring on Delaware Bay early this morning. The winds should lower
some this afternoon as the pressure gradient starts to weaken and
mixing also decreases. Will maintain the Small Craft Advisory
through early this afternoon, otherwise the conditions are
anticipated to be below advisory criteria through tonight.

Outlook...

Tuesday through Friday...Winds and seas are expected to be below
SCA criteria.

Rip Currents...

Today...Northerly winds 15-20 mph with gusts up to 30 mph will
gradually diminish some later this afternoon. Due to these elevated
winds and breaking waves of 2 to 3 feet, there is a MODERATE risk
for the development of dangerous rip currents for the Jersey Shore
and the Delaware Beaches.

Tuesday...Northeast to east winds near 10 mph with lower breaking
waves will result in a LOW risk for the development of dangerous
rip currents for the Jersey Shore and the Delaware Beaches.

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

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 1 PM EDT this afternoon for ANZ430-
     431.
     Small Craft Advisory until 1 PM EDT this afternoon for
     ANZ450>455.

&&

$$

SYNOPSIS...AKL/Gorse/Johnson
NEAR TERM...Gorse
SHORT TERM...AKL/Johnson
LONG TERM...AKL/Gorse/Johnson
AVIATION...Gorse/Johnson
MARINE...Gorse/Johnson