091
FXUS61 KPHI 230550
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
150 AM EDT Mon Sep 23 2024

.SYNOPSIS...
High pressure centered over eastern Canada continues to sag down
into the Northeast and Mid-Atlantic for the start of the new week.
This high will eventually lift to the north and east by the middle
of this week. Low pressure approaches from the west and will slowly
drag a cold front towards the region by the middle to end of this
week. Another area of high pressure may follow for next weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
Through the day time today, the mid and upper level short wave
ridge will weaken slightly as a very weak short wave trough
approaches from the west.

For most, the net effect will just be increasing clouds.
However, for some areas, scattered showers could work their way
into our region, primarily west of the I-95 corridor. Some high
rest models are especially bullish on the extent of shower
coverage this afternoon. This seems overdone given how weak the
trough is and how robust the surface/low level ridge will be
through the day. Thus,am generally on the lower end of guidance
for PoPs.

Have higher confidence in the increasing clouds, and thus,
temperatures being a few degrees lower today as compared to
yesterday. Highs are generally expected to range from the lower
60s in the southern Poconos to lower 70s for the 95 corridor.

What showers there will be will be mostly diurnally driven, so
expect coverage to wane after sunset, but will keep the low and
mid level clouds in place. This should be enough to preclude fog
development, but dewpoint depressions are expected to be quite
low, so will be watching trends closely.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
For the start of the short term, high pressure to the north and east
will gradually lift away. This will allow the low pressure system
and associated cold front to slowly make some progress eastward and
approach the Northeast and Mid-Atlantic.

The base of the high does look to build back down into the
Northeast on Tuesday, so much of Tuesday should end up dry with
seasonal temperatures in the lower 70s.

The frontal system will be able to make some eastern headway Tuesday
night, and showers will begin to spread east late Tuesday night and
continue into Wednesday. A bit of instability may come for daytime
Wednesday as the mid and upper level dynamics become more favorable.
This could result in a brief localized downpour or a rumble of
thunder. Generally, though precipitation totals for daytime
Wednesday look to be in the 0.1-0.75 range with the highest totals
in the western zones closer to the front.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Unsettled weather on tap to start the Long Term period before high
pressure potentially builds back in to end the week and for next
weekend.

As the mid-level trough approaches from the west later Wednesday
into Wednesday night, this may allow a secondary low to form on the
front as it passes through the region. Showers will become likely
for most of the region Wednesday night as this system passes
through. Cannot rule out a few thunderstorms as well.

There are some timing issues with how long it will take the front to
depart, so showers may continue into Thursday but much of Friday and
next weekend look dry. Will follow NBM PoPs and carry slight chance
(15-25%) PoPs Thursday across the area, then slight chance PoPs
limited to portions of the southern half of the region for Friday
through Sunday, though most of this period may end up being dry.

&&

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

Through 12Z...Prevailing VFR. There are some clouds around 2K
to 3K ft AGL, which are resulting in temporary MVFR ceilings at
some sites, but impacts are brief. Still some potential for
fog/BR development, but looking less likely given the clouds in
place, so have refrained from mentioning for most TAFs. Light
winds less around 5 kt. Moderate confidence.

Monday...Primarily VFR expected. As low clouds and showers build
closer to the region, MVFR ceilings will be possible after 18Z,
primarily for KRDG and KABE. Little chance for visibility
restrictions though. Easterly winds around 5-10 kt. Moderate
confidence.

Tonight...Ceilings are expected to lower into the MVFR category
for most TAF sites. As with Monday morning, there remains a
small chance for fog development, but this is unlikely given the
clouds that are expected to be in place. Light winds favoring an
easterly direction, but could have a variable direction if they
decouple enough. Moderate confidence.

Outlook...

Monday night through Tuesday... Mainly VFR, but sub-VFR conditions
possible with a few showers.

Tuesday night through Thursday...Periods of MVFR or IFR in SHRA.

Thursday night through Friday...Mainly VFR conditions expected.

&&

.MARINE...
Small Craft Advisories remain in effect for the ocean waters through
tomorrow, primarily for 4 to 6 ft seas. NE winds will generally
average 10 to 20 kts.

Sub-SCA conditions for Delaware Bay. Mainly NE winds around 10 to 15
kts.

Outlook...

Monday night through Tuesday...SCA in effect for the ocean waters,
mainly for elevated seas.

Tuesday night through Thursday...SCA may be needed for elevated seas
into the middle of next week.

Friday...Conditions likely below SCA criteria.

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 Tuesday. Persistent onshore flow will continue with NE to E
winds of 10 to 20 mph with gusts up to 25 mph along with 3 to 6 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, and will
continue to result in, a piling up of water along the coasts with
this water unable to drain within tidal waterways. Although
headlines are in effect through the Monday afternoon/night high tide
cycles, additional Coastal Flood Advisories may be needed for the
Tuesday afternoon/night high tide cycles.

For the Atlantic Coast, southern Raritan Bay, and Delaware Bay,
Coastal Flood Advisories remain in effect through the Monday
afternoon high tide cycles. A Coastal Flood Advisory may be needed
for some locations for the Tuesday afternoon high tide cycle.

For the tidal Delaware River, Coastal Flood Advisories remain in
effect through the Monday evening high tide cycle for minor coastal
flooding. A Coastal Flood Advisory may be needed for some locations
for the Tuesday evening high tide cycle.

For the northeastern shore of Maryland, Coastal Flood Advisories
remain in effect through the Monday night high tide cycles for minor
coastal flooding. A Coastal Flood Advisory may be also needed for
the Tuesday night high tide cycle.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Coastal Flood Advisory until 10 PM EDT this evening for PAZ070-
     071-106.
NJ...Coastal Flood Advisory until 6 PM EDT this evening for NJZ016.
     Coastal Flood Advisory until 5 PM EDT this afternoon for
     NJZ012>014-020>027.
     High Risk for Rip Currents through Tuesday evening for NJZ014-
     024>026.
     Coastal Flood Advisory until 10 PM EDT this evening for
     NJZ017>019.
DE...Coastal Flood Advisory until 6 PM EDT this evening for DEZ001.
     Coastal Flood Advisory until 5 PM EDT this afternoon for
     DEZ002>004.
     High Risk for Rip Currents through Tuesday evening for DEZ004.
MD...Coastal Flood Advisory until 5 AM EDT Tuesday for MDZ012.
     Coastal Flood Advisory until 2 AM EDT Tuesday for MDZ015-019-
     020.
MARINE...Small Craft Advisory until 6 PM EDT Tuesday for ANZ450>455.

&&

$$

SYNOPSIS...AKL/MPS
NEAR TERM...Johnson
SHORT TERM...AKL
LONG TERM...AKL
AVIATION...AKL/Johnson
MARINE...AKL/Kruzdlo/Wunderlin
TIDES/COASTAL FLOODING...