297
FXUS61 KPHI 241911
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
311 PM EDT Tue Sep 24 2024

.SYNOPSIS...
High pressure over Atlantic Canada will gradually retreat eastward
through Wednesday as a warm front starts to approach. Low pressure
associated with this warm front will move eastward Wednesday and
Thursday as it passes by to our north moving from Ontario and Quebec
into New England. By the weekend, the area will be situated between
high pressure to the north while low pressure will be to our south
and this pattern looks to potentially continue into early next
week.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
An upper ridge across the area has kept rains from developing/moving
across the region. The light onshore flow in the low levels has kept
clouds aplenty however. Temperatures have been running a little
below normal with upper 60s/low 70s common.

A low pressure system and its accompanying fronts to the west will
approach tonight, passing through Wednesday.  This will bring
increasing chances for showers late tonight (North/west) and other
areas Wednesday morning. The showers will linger across much of the
area Wed favoring the western areas however. High temperatures Wed.
will continue cool with mostly mid/upper 60s N/W and low 70s for
south NJ and Delmarva. Total rainfall will be three-quarters of an
inch for the NW areas and tapering to a tenth of an inch S/E for
Delmarva and south NJ. Winds will be E/SE around 10 mph much of
Wed.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/...
It will be a bit unsettled for parts of the short term period as a
system brings parts of the area some much needed rainfall.

Latest trends are for showers to continue through much of the
evening Wednesday into early Thursday before beginning to
diminish after daybreak. However, some isolated to scattered
showers may continue to linger for much of the day Thursday
particularly for areas near and especially north of the urban
corridor. This will occur as low pressure moves eastward from
Quebec into eastern New England while high pressure starts to
build back in over Central into western PA. Rain amounts for
Wednesday night through Thursday will be very minimal near the
coast with a tenth to a quarter inch possible near the urban
corridor and a quarter to half inch possible over parts of NE PA
into NW NJ. Expect skies to overall be partly to mostly cloudy
Thursday with it being warmer and more humid as we will be in
the warm sector. Highs will be mainly in the upper 70s to low
80s with dew points mainly in the mid to upper 60s. Weak surface
ridging should try to build east into the area Thursday night
keeping it mainly dry but with lingering cloud cover. Lows are
expected to range from the mid 50s north to the mid 60s south.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
There is more uncertainty than normal for the long range period as
the pattern will be quite complex over eastern North America. To
start the period early Friday, there will be an upper level low over
the Canadian Maritimes with another upper low near the Gulf
coast in the Lower Mississippi River Valley. Meanwhile upper
level ridging will be over the Great Lakes with a surface high
over PA. Finally, by this time the upper low near the Gulf coast
will have likely pulled in the tropical cyclone which should be
situated by this time somewhere over the SE CONUS. The main
uncertainty hinges around whether some of the moisture to our
south will be able to move northward bringing the area some rain
this weekend or whether the ridging to our north will suppress
it south. The latest guidance keeps the trend toward bringing
some decaying remnants of the system to our south a bit farther
north suggesting an increased chance for rain this weekend along
with more in the way of cloud cover. Given the continuing
uncertainty in the forecast, we stayed close to the NBM which
generally brings the area POPs of around 25 to 35 percent for
Friday-Friday night decreasing to 15-25 percent for Saturday
and Sunday.

If the upper level low to our south is able to move far enough north
to bring us rain for this weekend, this unsettled weather could
linger into early next week as the upper level pattern will be quite
blocky. As far as temperatures, they should be close to seasonal for
the long range period with highs mostly in the 70s.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas...

.Tonight... Low-end VFR CIGS across the area but not much in
the way of precip. Showers will arrive later tonight from west to
east affecting KRDG/KABE before heading towards the Delaware Valley.
CIGS lower thru the MVFR category and will be close to IFR by dawn.
East winds 5 to 10 knots. Medium confid overall.

.Wednesday... Low end MVFR or IFR during the morning with frequent
showers across the terminals. East winds around 10 knots. The
showers will diminish by the afternoon, but there is no much
confidence that CIGS will improve much during the afternoon as the
SE flow continues. Medium confid. overall.

Outlook...

Wednesday night through Thursday...Some showers along with low
stratus could bring sub VFR conditions at times, especially for RDG
and ABE.

Thursday night through Sunday...Mainly VFR conditions expected with
a slight chance for showers.

&&

.MARINE...
The onshore flow continues tonight and Wednesday with speeds below
SCA levels (mostly 10 to 15 kts). The enhanced seas (5 to 7 ft) will
slowly diminish through Wednesday so we`ll keep the SCA flag as it
is presently. Fair weather this evening then scattered showers are
expected for Wednesday.

Outlook...

Wednesday night...Seas expected to linger around 3-6 feet. Small
Craft Advisory in effect.

Thursday...Seas may continue to linger around 3-5 feet. SCA possible.

Thursday night-Sunday...Mainly sub-SCA conditions expected but
conditions may approach SCA criteria (20-25 kt gusts and 4-5 foot
seas) on Saturday.

Rip currents...

There is a HIGH risk for the development of dangerous and life
threatening rip currents at the Jersey Shore and at Delaware Beaches
through Wednesday. The persistent onshore flow continues with
easterly winds of 10 to 20 mph along with 3 to 5 ft breaking waves.

Rip currents occur often in the vicinities of jetties and piers and
the speed of the currents are generally maximized at low tides.

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

&&

.TIDES/COASTAL FLOODING...
A prolonged period of onshore flow has resulted in a piling up
of water along the coasts with this water unable to drain within
tidal waterways.

Coastal Flood Advisories are in effect today for Ocean County,
NJ and Sussex County, DE mainly for minor and spotty moderate
flooding in the back bays-Barnegat Bay in NJ, and Little
Assawoman Bay and the Indian River Inlet in Delaware. Thought
about extending the Advisory as some of the back bay tidal
guidance keeps minor flooding through Wednesday, but will wait
to see how today`s high tide cycle goes.

For Delaware Bay, a Coastal Flood Advisory is in effect for Kent
County, DE and Cumberland County, NJ for minor tidal flooding
with this afternoon`s high tide. Following this afternoon`s high
tide, no further advisories are anticipated.

For the Eastern Shore of Maryland, a Coastal Flood Advisory
remains in effect through tonight for minor tidal flooding
around tonight`s high tide. May need to extend for one more high
tide following tonight but will wait for more guidance to come
in and see how high the evening high tide gets.

Some spotty minor flooding remains possible along the southern
New Jersey coast, with no tidal issues expected along the
northern New Jersey coast (Monmouth and Middlesex County) and
along the tidal Delaware River.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...Coastal Flood Advisory until 6 PM EDT this evening for NJZ020-
     021-026.
     High Risk for Rip Currents through Wednesday evening for NJZ014-
     024>026.
DE...Coastal Flood Advisory until 6 PM EDT this evening for
     DEZ002>004.
     High Risk for Rip Currents through Wednesday evening for DEZ004.
MD...Coastal Flood Advisory until 5 AM EDT Wednesday for MDZ012.
     Coastal Flood Advisory until 2 AM EDT Wednesday for MDZ015-019-
     020.
MARINE...Small Craft Advisory until 6 AM EDT Thursday for ANZ450>455.

&&

$$

SYNOPSIS...AKL/Fitzsimmons
NEAR TERM...OHara
SHORT TERM...AKL/Fitzsimmons
LONG TERM...AKL/Fitzsimmons
AVIATION...AKL/OHara
MARINE...AKL/OHara
TIDES/COASTAL FLOODING...WFO PHI