492
FXUS61 KPHI 070008
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
808 PM EDT Sat Jul 6 2024

.SYNOPSIS...
A weak front arriving into our area tonight may dissipate late
Sunday into Monday. The next front arrives Tuesday night or
Wednesday, followed by another cold front Thursday which may then
linger in our area into next Saturday.

&&

.NEAR TERM /THROUGH SUNDAY/...
As of 6:15PM...Some minor adjustments to temperatures and
dewpoints for the next few hours, but no major changes to the
forecast at this time. All current heat headlines remain in
effect until 8PM due to heat indicies of 100-105+ degrees.

Heading into tonight, any storms should cease with the loss of
diurnal heating. However, a surface trough will virtually stall
over the coastal plain as some energy aloft streams up from the
south and west. Some of the hi-res model guidance is depicting
that a few showers or thunderstorms may make their way into the
southern Delmarva and even as far north as southern New Jersey
overnight. So, have increased PoPs in these areas. Outside of
this potential, just a mix of partly to mostly cloudy skies with
very mild overnight lows in the upper 60s to mid 70s. Some fog
development is possible especially in areas which experienced
rainfall earlier this afternoon.

For Sunday, there will be some `relief` from the very hot and humid
conditions compared to Saturday as dew points fall back into the
60s, however will remain upwards of 70 degrees along the coast.
Temperatures may be a degree or two cooler as well due to lingering
cloud cover. All this equates to heat indicies around 95-99 degrees.
This keeps the area below heat advisory criteria, so no heat
headlines are warranted. The majority of the area should remain dry
on Sunday as high pressure builds in from the west, except still
cannot rule out a brief shower over southern Delaware where the axis
of moisture remains highest.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
The hot and humid conditions continue, although the dew points may
be lowering at least some especially Monday.

Our region initially is forecast to be on the northwestern periphery
of a western Atlantic ridge, although there is an upper-level low
closed off tracking west and then southwest toward the Southeast
U.S. coast. Our sensible weather will be driven by surface high
pressure centered well to our east and keeping a southerly flow of
very warm and moist air. A weak front should be across our area,
although this may dissipate or become a surface trough. There may
not be much convective chances through Monday as some drying looks
to occur. Still cannot rule out a spotty shower or thunderstorm
though Monday afternoon and evening especially near and north/west
of I-95 given ample instability once again. Some guidance suggests
that the surface dew points though mix down more Monday afternoon,
and if this occurs then the peak heat indices would tend to stay
below advisory criteria for the entire area.

As we go through Tuesday, the ridge starts to shift southward some
as an upper-level trough slides across the Midwest and Great Lakes
regions. This will send another front into our area and help provide
some increase in lift for some convection. The greater chances for
this looks to be across our northern and western areas which are
closer to the incoming trough and also the front. Temperatures
should be a little cooler with the anticipation of more clouds and
an increase in some convection, however it will still be hot and
humid across the region. While peak heat indices may end up being
below advisory criteria across the region, they are currently
forecast to be near 100 degrees especially for the I-95 corridor
down into Delmarva. While the stronger flow aloft may be displaced
farther to our north and west, high moisture content air will lead
to locally heavy rainfall with any stronger convection.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Summary...At least some cooling should take place for a time along
with increasing convective chances as remnant tropical moisture
may team up with a cold front.

Synoptic Overview...An upper-level trough sliding across eastern
Canada is forecast to mostly glance the Northeast U.S. Wednesday
into Thursday. This drives another cold front into our area, however
given the trough aloft lifting away from our region this front may
stall in place. At least some tropical moisture may then increase
across our area from about Thursday and Friday, as the remnant
moisture from Beryl gets tangled up with the aforementioned cold
front. Given the lack of a stronger trough aloft, the front may
linger across our area right through Saturday.

For Wednesday...Hot and humid as a weak front bisects the region and
an upper-level trough slides across New England. Our region looks to
be glanced by this upper-level trough, however its associated front
should be enough within a hot, humid and buoyant air mass to develop
some convection. This should be mostly during the afternoon and
evening. Some additional tropical moisture potentially starting to
stream in from the west or southwest with the remnants of Beryl may
enhance the convection chances at least some. Afternoon temperatures
should get into the lower 90s for many places and with dew points in
the 70s, peak afternoon heat indices should top out right near 100
degrees for parts of the I-95 corridor and points south and east
especially (away from the coast due to a sea breeze).

For Thursday through Saturday...At least a portion of this time
frame could become increasingly convectively active. Some building
of a ridge is forecast overall across the western Atlantic with a
front potentially stalled across our region. A shortwave trough,
which could very well be the remnants of Beryl, may track near or
across our area Thursday and Friday. If this were to occur,
additional tropical moisture will be feed into the shearing mid
level shortwave associated with it. As a result, increasing
convective development could be realized with areas of very heavy
rain. The unsettled conditions may linger right through Saturday as
a conduit for tropical moisture and lift becomes positioned across
our area. This will depend on where this zone sets up between a
ridge to our east and a trough across the Mississippi Valley. The
extent of the cloud cover and convection will also have an impact on
temperatures. As of now, some cooling should occur for a time with
increased convection, however it is forecast to remain rather
humid.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

Tonight...VFR expected for most sites. VCSH possible at times
for sites southeast of the I-95 corridor. KACY may see MVFR
ceilings 6Z onwards. Chance of lower visibilities for KMIV/KACY
with areas of fog. SW winds will gradually veer and become NW
around 5 kts or less. Many sites will see winds go light and
variable for periods of time. Moderate confidence.

Sunday...VFR. No significant weather expected. Light and
variable winds around 5 kts. Winds should become SE-S at KACY
due to seabreeze development in the afternoon. High confidence.

Outlook...

Sunday night...VFR overall.

Monday through Thursday...Some mainly afternoon showers and
thunderstorms, with these possibly the most numerous on Thursday,
should result in times of sub-VFR conditions.

&&

.MARINE...
Into tonight, south-southwest winds around 15-20 kt will
diminish to 5-15 kt overnight. Seas around 3-4 feet. South-
southwest winds around 10 kt continue for Sunday with seas
around 2-3 feet.

There remains the potential for some dense marine fog to
develop late tonight into Sunday due to warm air over the
cooler upwelled waters of the Atlantic.

Outlook...

Sunday night through Thursday, the conditions are anticipated to be
below Small Craft Advisory criteria. However, some thunderstorms
especially each afternoon and evening could produce locally gusty
winds (most numerous possibly on Thursday).

Rip Currents...

Through this evening, south winds will average 10 to 15 mph
with gusts up to 20 mph. With an onshore component in New
Jersey, this results in a MODERATE risk for the development of
dangerous rip currents for the Jersey Shore. Since this
direction is a bit more parallel to the coast, if not a bit
offshore, in Delaware, this results in a LOW risk for dangerous
rip currents at the Delaware Beaches.

On Sunday, winds will be lighter and a bit more onshore. This results
in a MODERATE risk for the development of dangerous rip currents
at the Jersey Shore, mainly south of Monmouth county. For
Monmouth county and the Delaware Beaches, there is a LOW risk
for the development of dangerous rip currents.

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

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Excessive Heat Warning until 8 PM EDT this evening for PAZ070-
     071-104-106.
     Heat Advisory until 8 PM EDT this evening for PAZ060>062-
     101>103-105.
NJ...Excessive Heat Warning until 8 PM EDT this evening for NJZ010-
     012-013-015>023-027.
     Heat Advisory until 8 PM EDT this evening for NJZ001-007>009.
     Air Quality Alert from 11 AM to 11 PM EDT Sunday for
     NJZ008>010-012>015-017>020-026-027.
DE...Excessive Heat Warning until 8 PM EDT this evening for
     DEZ001>003.
MD...Excessive Heat Warning until 8 PM EDT this evening for MDZ012-
     015-019-020.
MARINE...None.

&&

$$

SYNOPSIS...Gorse
NEAR TERM...DeSilva/Wunderlin
SHORT TERM...Gorse
LONG TERM...Gorse
AVIATION...DeSilva/Gorse/Wunderlin
MARINE...DeSilva/Gorse/Wunderlin