471
FXUS61 KPHI 080540
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
140 AM EDT Mon Jul 8 2024

.SYNOPSIS...
A weak front across our area should dissipate tonight or Monday. The
next weak front approaches Tuesday night or Wednesday, then a cold
front arrives Friday and into next weekend.

&&

.NEAR TERM /THROUGH TODAY/...
Aside from the development of fog tonight, some of which could
be locally dense, generally quiet for tonight, through quite
warm and humid.

Tonight, stalled boundary will begin to retreat back to the
west as weak surface flow becomes more onshore. This will allow
higher dew points to work their way back into the area. Skies
should remain partly to mostly cloudy for most of the night with
lows in the upper 60s to mid 70s. Areas of fog are likely to
develop especially along the coast and in any areas that
received rainfall this afternoon. The setup looks ideal for
dense marine fog to develop at least, but how dense and far fog
penetrates/develops inland is not very certain at this point. A
dense fog advisory is not out of the question for coastal and
some inland areas later tonight.

The hot/humid conditions continue on Monday as there isn`t all that
much change with the upper level pattern. Morning clouds and fog
will give way to a mix of sun and clouds during the afternoon. A
slight chance of a shower/storm is possible north and west, where
there is some forcing near the retreating boundary. High temps will
be in the low to mid 90s across interior locations with 80s in the
Poconos and along the coast. The biggest change for Monday is that
dew points are forecast to be at least a few degrees higher in the
upper 60s to mid 70s. The combination of these T/Td`s yield heat
indicies around 98-102 degrees across much of the area. For this
reason, have issued a Heat Advisory for all of our NJ counties
except Cape May, all of our PA counties except Carbon/Monroe, and
New Castle County in Delaware beginning at 10 AM Monday.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
Hot and humid conditions continue. A Heat Advisory has been issued
for much of the area through at least Tuesday.

An upper-level trough is forecast to be gradually shifting eastward
from the Midwest, upper Great Lakes and the Mississippi Valley. The
remnant energy of tropical cyclone Beryl is forecast to eventually
become absorbed into this trough either Tuesday or Wednesday.
Meanwhile to the east, a ridge remains in place across the western
Atlantic into the Southeast U.S. Deepening southerly flow between
these systems will maintain a very humid air mass in place with dew
points into the 70s. In addition, temperatures are forecast to
remain hot into Wednesday with enough sunshine and also a warm start
to each morning. A cold front to the northwest may approach later
Tuesday, however this may not get into our area as low pressure
(remnants of Beryl) tracks into the Great Lakes and maintains a more
northerly position of this front. While some additional clouds may
occur, ample heating is expected to result in afternoon temperatures
peaking into the low to perhaps mid 90s both days for much of the
area. This combined with dew points in the 70s will result in peak
afternoon heat indices reaching or exceeding 100 degrees. For now,
the Heat Advisory goes into Tuesday evening however it is probable
that this will need to be extended into Wednesday and perhaps even
expanded southward. It is possible that peak heat indices reach
warning criteria (105F+) for areas of the coastal plain including
the urban I-95 corridor particularly on Wednesday. To keep the
headline/messaging more simple carried the advisory through Tuesday
for now.

As of convective chances through Wednesday, there may not be much
Monday night and Tuesday as the overall forcing for ascent is
forecast to be well to our southwest and west. If the aforementioned
front is able to drop farther southeastward by later Tuesday, then
that may result in some uptick in convection. There is a greater
chance for some showers and thunderstorms especially farther north
and west across our area on Wednesday as some increased forcing for
ascent starts to arrive from the west. This however will depend on
the track and even timing of the remnants of Beryl to our west.
Increasing precipitable water values will result in local areas of
heavy rainfall with the stronger convection. As of now, the
probability of severe thunderstorms looks to be low given the track
of the low so far removed from our area.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
Summary...Shower and thunderstorm chances continue along with humid
conditions, however some cooling should occur for a time.

Synoptic Overview...An upper-level trough is forecast to be sliding
eastward from the Great Lakes, Midwest and Mississippi Valley
Thursday. This trough should have absorbed the remnant energy from
Beryl as it tracks up across the Great Lakes then into adjacent
Canada. This trough and energy may be slow to shift eastward however
Friday into Saturday as it looks like the western Atlantic ridge
takes longer to shift east and erode on its western flank. The upper-
level trough is then forecast to settle into the Northeast and Mid-
Atlantic regions later Saturday and especially Sunday. At the
surface, a front is forecast to arrive later Thursday and Friday as
the remnants of Beryl track well to our northwest. The front may
stall in our area before either weakening of dissipating into Sunday.

For Thursday and Friday...The remnant low of Beryl is forecast to
track north-northeastward across the Great Lakes region Thursday.
Despite this track well to our northwest, an upper-level trough
positioned to our west will assist in advecting a plume of tropical
moisture up across our area. This will result in some increase in
showers and thunderstorms, however the main forcing for ascent may
just glance a portion of our area and this could limit the
convective coverage especially on Thursday. There could be a bit
more increase in convection Friday as a cold front starts to arrive
into our area, with some better focus for convergence possible.
Locally heavy rain will accompany any stronger convective elements.
It will remain humid, however temperatures should be stepping down
at least some with the anticipation of more clouds and some
convection.

For Saturday and Sunday...The upper-level trough is forecast to
gradually overspread the region during this time. A surface cold
front may stall across our region Saturday, then potentially weaken
or dissipate into Sunday. A conduit of higher moisture content air
along with some forcing by the trough and lingering surface front,
should help focus some additional convection. The system overall
looks to be on the weaker side regarding a true air mass change,
therefore very warm to hot conditions continue although the dew
points may start to lower Sunday as the trough axis arrives.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

Rest of tonight (through 12Z)...Primarily VFR for all terminals
with scattered mid- high clouds. The exception is at
MIV/ACY where the development of fog and/or mist is probable.
At these terminals, expect periods of IFR/LIFR visibilities
and/or ceilings. For the I-95 terminals (PHL/PNE/TTN/ILG) could
see some MVFR fog move in from the coast as well, but will
struggle to be prevailing, so added a TEMPO fog group to address
that. Winds light and variable. Moderate confidence, overall.

Monday...VFR expected. SE winds around 5-10 kt. A slight chance
of a thunderstorm at RDG/ABE. High confidence.

Outlook...

Monday night...VFR.

Tuesday through Friday...Some times of sub-VFR conditions mainly
during any showers and thunderstorms.

&&

.MARINE...
Will go ahead and start the Marine Dense Fog Advisory for all
waters with this update as fog continue to develop on the
waters. This Marine Dense Fog Advisory is in effect until 10 AM
Monday. Dense Fog Advisories may need extension into the
afternoon time frame. Fair weather expected thereafter. Winds
will remain south-southeasterly around 5-10 kt with seas around
2-3 feet through Monday.

Outlook...

Monday night through Wednesday...The conditions should be below
Small Craft Advisory criteria. However, some thunderstorms
especially Wednesday afternoon and evening could produce locally
gusty winds.

Thursday and Friday...Winds and seas should increase some, however
mostly staying below Small Craft Advisory criteria. Some
thunderstorms possible which may produce locally gusty winds.

Rip Currents...

For Monday, winds will remain east to southeast 5-10 mph, while
waves on the ocean will be around 2 feet with a 5-8 second
period. This will lead to surf height waves of 1-2 feet. There
for the Rip Current Risk will be LOW on Monday.

On Tuesday, winds shift more out of the south and increase to
10-15 mph, while the waves on the ocean will increase to 2-3
feet with a 5-7 second period. This will lead to surf heights
waves of 1-3 feet. The Rip Current Risk will be LOW on Tuesday,
but be monitored for a possible upgrade to MODERATE.

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

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Heat Advisory from 10 AM this morning to 8 PM EDT Tuesday for
     PAZ060>062-070-071-101>106.
NJ...Heat Advisory from 10 AM this morning to 8 PM EDT Tuesday for
     NJZ001-007>010-012-013-015>022-027.
DE...Heat Advisory from 10 AM this morning to 8 PM EDT Tuesday for
     DEZ001.
MD...None.
MARINE...Dense Fog Advisory until 10 AM EDT this morning for ANZ430-431-
     450>455.

&&

$$

SYNOPSIS...Gorse/Johnson
NEAR TERM...DeSilva/MJL/MPS/Wunderlin
SHORT TERM...Gorse
LONG TERM...Gorse
AVIATION...DeSilva/Gorse/MJL
MARINE...DeSilva/Gorse/MPS/Robertson/Wunderlin