687
FXUS61 KPHI 010803
AFDPHI

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

.SYNOPSIS...
High pressure builds in today through Tuesday before moving offshore
Wednesday. A more active period resumes Thursday with the arrival of
a surface trough but a cold front may not push through the region
until towards the end of this coming weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
A significant air mass change has occurred 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 NIGHT/...
High pressure remains the name of the game during the short term
forecast period. This will continue a dry and overall pleasant start
to the new month across the region. Highs on Tuesday will be near
normal, mainly in the low-mid 80s. However, dew points forecast to
remain in the 50s. Additionally, the high looks to be centered
fairly directly over the region during this time period, leading to
light winds across most of the region outside of a sea breeze
potentially developing in the afternoon hours. All together, another
pleasant day looks to be on tap. Lows Tuesday night will be a touch
warmer compared to Monday night as well, mainly in the low-mid 60s.

The high will continue to progress eastward Tuesday night into
Wednesday and slide offshore. This will shift winds to be more
southerly, strengthen slightly, and begin to slowly draw more warm
and moist air back into the region. Wednesday looks to remain
pleasant overall though with highs mainly in the mid-upper 80s and
dew points in the upper 50s to near 60. Wednesday night lows are
forecast to fall into the mid 60s with upper 60s to near 70 in the
heart of the I-95 corridor.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
The forecast for the long term period is largely unchanged, an
increase in activity is still expected with decreasing influence
from high pressure as an upper-level trough across Canada suppresses
the upper-level ridge southward. Models continue to indicate the
formation of a secondary trough over the Midwest and potential slow
progression eastward.

With a series of shortwave impulses pushing through the region ahead
of the upper-level trough, chances for showers and thunderstorms
exist for each day of the long term period. Owing to a lack of
uncertainty in upper-level support, chances generally peak around 30-
40 percent right now and are focused on the afternoon and evening
hours of each day. What is looking more likely with this forecast
update, is the lack of relief from increasingly humid conditions
through the end of the week if the upper-level trough remains back
to the west. While high temperatures are forecast to remain steady
in the upper 80s to low 90s, dew points look to continue to increase
through the end of this week, potentially rising into the mid 70s.
Some relief may arrive by next Sunday but that will be highly
dependent on the amplitude of the upper-level trough and the
strength of the associated surface cold front.

&&

.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 (30-
40%) for SHRA and TSRA, especially in the afternoon and evening.

&&

.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...Conditions are forecast to be below Small
Craft Advisory 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
NEAR TERM...Gorse
SHORT TERM...AKL
LONG TERM...AKL
AVIATION...AKL/Gorse
MARINE...AKL/Gorse