-- Discussion containing changed information from previous version are highlighted. --
610
FXUS61 KPHI 220546
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
146 AM EDT Sun Sep 22 2024

.SYNOPSIS...
Low pressure continues to meander off the East Coast. It will
drift to the south and east early during the upcoming work week.
Meanwhile, high pressure is extended over the region but will slowly
move offshore and eastward Sunday into Monday. A slow moving cold
front then approaches from the west, and low pressure may develop
on that front and impact the region late next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
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Showers and storms associated with the weak shortwave trough
continue to progress southeastward from Central PA into MD.
Based on the latest satellite and radar trends, showers and
storms are weakening, and will likely only clip portions of
Berks Co, Chester Co and NE MD before they completely dissipate
later this morning. By mid day, the short wave trough will be
southeast of our region, with mid level short wave ridging
building in, bringing a return to dry conditions.

The other weather concern, both early this morning and again
Sunday night is the potential for fog to develop. For this
morning, we`ve already seen low and mid level clouds build in,
so seems unlikely we`ll see much more than patchy shallow fog.
For Sunday night, there will be less in the way of low/mid level
clouds, but there will be increasing high level clouds. It is
uncertain if this will be enough to suppress fog development,
so have continued with a mention of patchy fog.
-- End Changed Discussion --


&&

.SHORT TERM /MONDAY THROUGH TUESDAY/...
A wedge of high pressure will continue to be over the Northeast
and Mid-Atlantic Sunday night into Monday before lifting away
Monday night. A slow-moving cold front then begins to approach
the region late Monday but may stall out to our west as the
initial upper level low becomes cutoff. However, shortwave
energy diving out ahead of the front may trigger some showers
late Monday through Tuesday. PoPs will mostly be slight chance
from late Monday through midnight or so Monday night, but then
PoPs increase to chance after midnight Monday night before
decreasing once again by later Tuesday. The highest PoPs are
focused on the most western portion of the region which will be
closest to the stalling front. As has mostly been the case, QPF
will be light.

Lows Sunday night and Monday night will generally be in the
50s, though around 60 at the immediate coasts due to the warmer
ocean temperatures. Highs on Monday will once again be in the
low to mid 70s with temperatures right around 70 for Tuesday.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
The Long Term period will feature a prolonged period of
unsettled weather.

By Tuesday night, a new upper-level trough begins to push
eastward across the Great Lakes towards the Northeastern US
while a cutoff low lingers over the southern Plains. This
movement in the upper-levels looks to help move the surface low
pressure along and drag the front into the local area Wednesday
into Thursday. With the front approaching and increasing
shortwave energy, showers look to become more widespread in this
time period. This would bring more in the way of rainfall to
the area from Tuesday night through Wednesday night period.
Will follow NBM and go with likely PoPs during that time.
However, there remains inconsistencies among the models, so
this may change.

The front may not fully clear the region until Friday or so, as
another cutoff upper-level low may develop, and unsettled
weather may remain in place until then as a result.

Temperatures will be at or a few degrees below normal during
this time.

&&

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

Through 12Z...MVFR ceilings are building in and should
eventually move over all TAF sites, although impacts at most TAF
sites probably won`t last long (exceptions being KMIV, KACY
where onshore flow will probably keep the ceilings in place
through at least 12Z). Showers and storms to the west of most
TAF sites, but have already clipped KRDG, and may approach KILG
later. Winds should generally favor northeasterly, but are light
enough (generally 6 kt or less), that direction could be
variable at times. Moderate confidence.

Sunday...Once the MVFR ceilings dissipate by 15Z (will dissipate
at most TAF sites by 12Z, but could hang on longer at KACY and
KMIV), will have VFR through the remainder of the day. Winds
northeasterly or easterly around 10 kt or less. Moderate
confidence.

Tonight...Prevailing VFR. There is a small chance (20%) that
patchy fog will develop. But confidence is too low in potential
areas as well as the extent to include in the TAFs at this time.
If it does develop, MVFR or even IFR ceilings may be possible.
Moderate confidence.

Outlook...

Monday...Primarily VFR conditions.

Monday night through Tuesday...VFR, though MVFR or IFR possible
in SHRA.

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

.MARINE...
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Small Craft Advisories on the Atlantic coastal waters today and
tonight, primarily due to elevated seas. On the Delaware Bay,
winds and waves should remain below SCA criteria.

Outlook...

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

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

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 Monday. NE winds will range from 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
-- End Changed Discussion --

&&

.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. At least minor
tidal flooding is expected for the next several high tide cycles for
most portions of the area. Moderate tidal flooding could possibly
occur again for some portions of the area Sunday.

Changes to headlines:

Coastal Flood Warning has been dropped for most of the Atlantic
coast and Delaware Bay and replaced with advisories covering through
the Monday morning/afternoon high tide cycle. However, will keep the
Coastal Flood Warning for Cape May and Cumberland counties in New
Jersey and for Kent County in Delaware through the Sunday
morning/afternoon high tide cycle. These areas may experience some
moderate coastal flooding once again on Sunday. Thereafter, a
Coastal Flood Advisory is in effect for these areas as is for the
rest of the Atlantic coast and Delaware Bay.

For the tidal Delaware River, Coastal Flood Advisories are in effect
through the late Monday high tide cycle for minor coastal flooding.

For the northeastern shore of Maryland, it looks like minor coastal
flooding will begin with the high tide cycle tonight.
This also now includes Kent county, Maryland. Will go ahead and
issue Coastal Flood Advisories through the Monday evening high tide
cycles; it looks like it will be the evening high tide cycles that
will be most impacted by minor coastal flooding.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
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PA...Coastal Flood Advisory until 10 PM EDT Monday for PAZ070-071-
     106.
NJ...Coastal Flood Advisory until 6 PM EDT Monday for NJZ016.
     Coastal Flood Warning until 5 PM EDT this afternoon for NJZ021-
     023-024.
     Coastal Flood Advisory from 5 PM this afternoon to 5 PM EDT
     Monday for NJZ021-023-024.
     Coastal Flood Advisory until 5 PM EDT Monday for NJZ012>014-
     020-022-025>027.
     High Risk for Rip Currents through Monday evening for NJZ014-
     024>026.
     Coastal Flood Advisory until 10 PM EDT Monday for NJZ017>019.
DE...Coastal Flood Advisory until 6 PM EDT Monday for DEZ001.
     Coastal Flood Warning until 5 PM EDT this afternoon for DEZ002.
     Coastal Flood Advisory from 5 PM this afternoon to 5 PM EDT
     Monday for DEZ002.
     Coastal Flood Advisory until 5 PM EDT Monday for DEZ003-004.
     High Risk for Rip Currents through Monday 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 Monday for ANZ450>455.
-- End Changed Discussion --

&&

$$

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