021
FXUS61 KPHI 060552
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
152 AM EDT Sat Jul 6 2024

.SYNOPSIS...
High pressure dissipates offshore this evening. A cold front
slowly crosses the area through Sunday. High pressure returns
for Sunday night and Monday before another slow moving low
pressure system encroaches upon the area through the middle of
next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1 AM, the next round of showers and storms was starting to
develop over central PA. These should propagate northeastward
across the southern Poconos, NW NJ, Lehigh Valley, and Berks
County through sunrise.

After the morning round gets out of our region, expect at least
a few hours lull before the next round of showers and storms
develops near/along the weak cold front progressing into our
region. The cold front is rather weak, and there is weak forcing
in the mid and upper levels. Consequently, have low confidence
in the timing and extent of this round of showers and storms. It
does appear though that by the time anything would start to
develop, the front should be near or east of the fall line.
Consequently, reduced PoPs along and west of the fall line for
this afternoon and evening. This round of showers and storms
should gradually shift further south and east. That being said,
the front will likely stall out over our coastal plains later
today.

The other big weather story today is the continued heat and
humidity. Even with increased cloud cover likely tempering
ambient temperatures slightly, dewpoints still well into the
70s, especially for areas along and east of the fall line, will
lead to widespread heat index values above 100 F

&&

.SHORT TERM /SUNDAY THROUGH MONDAY/...
Not much change in the short-term forecast through Monday. The
cold front still looks on pace to cross the area on Sunday but
as it does so, it will be washing out and moving at a snails
pace. Ultimately, the front should just leave a remnant boundary
behind. As a result, Sunday should be a fairly nice day for
most as high pressure builds in from the north and west with
just a slight chance of showers across the Delmarva and southern
NJ. High temps should again be in the upper 80s to low 90s, but
dew points will fall back into the 60s behind the front. At
this point, no heat headlines are expected, but if the front
hangs up a bit more to the north and west this may need to be
reconsidered. Skies should begin to clear out a bit into Sunday
night except over the Delmarva where a few showers may linger.
Lows will remain though in the upper 60s to mid 70s as moisture
content is still quite high.

High pressure will win out on Monday for most areas leading to
a mostly tranquil day with a mix of sun and clouds during the
afternoon. However, with the remnant boundary lingering overhead
and subtle increase in moisture return with dew points rising
back into the lower 70s, a few showers or thunderstorms will be
possible north and west of the I-95 corridor. As mentioned
above, dew points will be slightly higher and air temps will be
a degree or two higher as well on Monday. Heat indicies will
hover between 95-99 degrees for much of the area. Will continue
to evaluate trends amongst T/Td guidance over the next several
days in order to determine if any heat headlines will be needed
for Monday.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
The long term period as a whole is summarized to be quite
unsettled with seasonable temperatures. An upper level trough
will be over the Great Lakes region Monday night into Tuesday
before shifting east over the Northeast US through Wednesday.
But this is where the forecast details becomes uncertain because
there will be several impulses embedded in the upper flow,
allowing several fronts and boundaries to be near our region.
This will result in several opportunities for some showers and
thunderstorms, mostly in the afternoon and evening hours due to
diurnal effects. Right now, the greatest chance for
showers/storms looks to be Tuesday into Wednesday. After
Wednesday, deterministic and ensemble guidance differs
significantly, so have held a chance of showers/storms through
the end of next week to account for variability amongst guidance
suites.

&&

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

Through today...low stratus at the coast, including KACY, should
dissipate by 12Z. An initial round of SHRA and TSRA may affect
KRDG, KABE, and KTTN through 12Z. A second round of SHRA and
TSRA could develop in the Delaware Valley (near KILG, KPHL,
KPNE, and KTTN) between 16 and 20Z and progress eastward towards
the coast, including KMIV and KACY. However, there is low
confidence in the timing and extent of this second round.
Outside of those exceptions, prevailing VFR is expected. Winds,
generally less than 10 kt, will start prevailing S, but become
more SW through the day. Low confidence.

Tonight...Starting prevailing VFR. There is a small chance for
another round of low stratus, especially at KACY and KMIV after
06Z. Winds gradually becoming NW, but speeds below 10 KT.
Moderate confidence on the overall pattern, but low confidence
on the potential for low stratus.

Outlook...

Sunday through Monday night...VFR expected. A slight chance of
a shower or thunderstorm possible Sunday night into Monday.
Otherwise, no significant weather anticipated.

Tuesday through Wednesday...Sub-VFR conditions possible. A chance of
showers and thunderstorms possible with occasional mist/fog.

&&

.MARINE...
Small craft advisories in effect through Saturday evening.

South winds 15-20 kts with gusts near 25 kts across the Atlantic
waters. Seas 4-5 feet build to 4-6 feet Friday night.

Winds and seas remain elevated through the first part of
Saturday with showers and storms possible. Winds and seas begin
to diminish later afternoon/early evening.

Outlook...

Saturday Night...Winds and seas fall below SCA criteria late
evening. Wind gusts to 20 kt. Wave heights up to 5 feet,
diminishing to 3 to 4 feet. Chance TSRA.

Sunday through Monday night...No marine headlines expected. Winds
generally less than 15 kt and seas of 2-3 feet. A slight chance of a
shower or thunderstorm into Sunday night, otherwise fair weather
expected.

Tuesday through Wednesday...No marine headlines expected. Winds
generally less than 20 kt and seas of 2-3 feet. A chance of
thunderstorms expected.

Rip Currents...

The effects of a New Moon today will linger into the weekend. On
Saturday, 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 and life
threatening 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 Delaware Beaches.

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

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

&&

.TIDES/COASTAL FLOODING...
With the New Moon to occur today, some locations may see some
spotty minor coastal flooding during the next few high tide
cycles.

With continuing S/SE flow and the approach of the New Moon,
some guidance has areas of Cumberland County NJ seeing advisory
minor coastal flooding with the upcoming evening high tide
cycle. Though guidance may be running a bit high, a short-fused
coastal flood advisory may be needed later on.

&&

.CLIMATE...
Near record breaking warmest low temperatures are forecast on
Saturday. Records for our climate sites are listed below:

Record Warmest Low Temperatures
                           July 6
Site                  Record/Year
Allentown (ABE)           74/1999
AC Airport (ACY)          76/1999
AC Marina (55N)           80/1999
Georgetown (GED)          78/2012
Mount Pocono (MPO)        71/1999
Philadelphia (PHL)        79/1999
Reading (RDG)             75/1934
Trenton (TTN)             76/1999
Wilmington (ILG)          77/1999

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Heat Advisory until 8 PM EDT this evening for PAZ060>062-070-
     071-101>106.
NJ...Heat Advisory until 8 PM EDT this evening for NJZ001-007>010-
     012-013-015>023-027.
     Air Quality Alert from 11 AM to 11 PM EDT Sunday for
     NJZ008>010-012>015-017>020-026-027.
DE...Heat Advisory until 8 PM EDT this evening for DEZ001>003.
MD...Heat Advisory until 8 PM EDT this evening for MDZ012-015-019-
     020.
MARINE...Small Craft Advisory until 8 PM EDT this evening for
     ANZ450>455.

&&

$$

SYNOPSIS...DeSilva
NEAR TERM...Johnson
SHORT TERM...DeSilva
LONG TERM...DeSilva
AVIATION...DeSilva/Johnson
MARINE...DeSilva/MJL/MPS
TIDES/COASTAL FLOODING...
CLIMATE...