-- Discussion containing changed information from previous version are highlighted. --
333
FXUS61 KPHI 210543
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
143 AM EDT Sat Sep 21 2024

.SYNOPSIS...
Low pressure will continue to spin off of the East Coast, while
high pressure will remain from eastern Canada into the eastern
United States through early next week. A weak disturbance is
expected to move across the area Saturday night, before a
stronger low pressure system possibly impacts the area by the
middle of next week.

&&

.NEAR TERM /THROUGH TODAY/...
-- Changed Discussion --
Low pressure will meander some 300 miles east of the Jersey
Shore today through tonight. Meanwhile, surface high pressure
over the southern Province of Ontario will build down into the
eastern Great Lakes and Ohio Valley, and even down into the
southern Appalachians.

Quiet weather conditions continue through the overnight hours
with some light patchy fog possible if the winds end up staying
decoupled through the night. By mid morning the looks to be a
brief break in the clouds with mostly sunny skies persisting high
pressure remains ridged over the eastern US.
-- End Changed Discussion --

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
The strong low pressure system will continue to meander offshore
through the weekend as a weak high pressure system tries dipping
down the east coast from from eastern Canada. Saturday night, a weak
short wave trough in the mid and upper levels digs into the western
portions of our region. This could result in some showers primarily
west of the I95 corridor. It doesn`t seem to be anything significant
however there`s a moderate (30-50%) chance of showers developing
over central PA. As mentioned by previous shifts, since this is more
due to broader and weaker synoptic scale lift, this does not appear
to be anything widespread or of enough moisture to put a significant
dent in the dry conditions.

The rain chances, at least with this round will be short-lived as
short wave ridging starts to build closer by Sunday morning,
resulting in a return to dry conditions.

Temps will be fairly seasonable within a few degrees of normal for
daytime highs and overnight lows for this time of the year.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
No significant changes with the long term. The high pressure/dry
conditions continue into Monday. However, most guidance still
depicts the return of some much needed rain moving into the region
during the middle of the week.

A messy frontal system is forecast to move eastward as a an area of
low pressure moves across the Ohio River Vally and into the eastern
Great Lakes Tuesday through Thursday. The exact dynamics of what
will cause the rainfall is still a bit uncertain as it may be a
front that swings all the way through or a secondary low pressure
that potentially develops and impacts the area around Thursday.
Either way, ensemble guidance is showing at least moderate (40-60%)
chances for rainfall through the middle of the week which should be
helpful given  conditions have been abnormally dry for the last
month for many areas.

One note, while we currently have rain shower chances from
Tuesday through Thursday, it is unlikely we will see rain
throughout that entire period. Due to uncertainty with how this
system will evolve, it is difficult at this point to further
refine the time period we are most likely to see rain.

&&

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

Tonight...VFR expected, however, patchy fog may result in MVFR or
lower conditions. Light N to NE winds.

Saturday...Briefly lowered cigs will quickly become VFR through
the day. NE to E winds 5 to 10 knots.

Outlook...

Saturday night...Generally VFR with MVFR or IFR possible in
showers.

Sunday - Monday...VFR conditions expected.

Monday night-Wednesday...VFR prevailing with brief periods of
MVFR or IFR possible in showers.
-- End Changed Discussion --

&&

.MARINE...
Low pressure meanders several hundred miles east of the Jersey
Shore.

Small Craft Advisories are in effect for the ocean waters through
Saturday, primarily for 4 to 6 ft seas. However, there will be
occasional gusts around 25 knots this afternoon. Otherwise, NE
winds will average 15 to 20 kt.

Sub-SCA conditions for Delaware Bay. E winds around 10 kt this
afternoon will turn N tonight.

Outlook...

Saturday night through Sunday night...Small Craft Advisory in
effect on the Atlantic coastal waters due to elevated seas.

Monday-Wednesday...Small Craft Advisory conditions likely
for at least part of this period before we see gradual
improvement especially Tuesday into Wednesday.

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 Sunday. N to NE winds will range from 10 to 20 mph with
gusts up to 25 mph along with 3 to 6 ft breaking waves.

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

&&

.TIDES/COASTAL FLOODING...
Continued onshore flow will result in water piling up and
unable to drain within tidal waterways. At least minor tidal
flooding is expected for the next several high tide cycles for
most portions of our area. Moderate tidal flooding is likely to
occur for portions of our area Saturday, and may possibly
occur with the high tide cycle Sunday.

For the Atlantic coast and Delaware Bay, no changes to
headlines at this time. However, confidence is now fairly
certain that tidal flooding of moderate levels will be reached
for most locations Saturday; confidence remains low that tidal
flooding of moderate levels will be reached for portions of our
area Sunday. Coastal Flood Warnings will likely be issued during
the overnight update.

For the tidal Delaware River, there is increasing concern for
widespread minor flooding, starting with the high tide this
afternoon/evening. Have issued Coastal Flood advisories into
the weekend.

For the northeastern shore of Maryland, it looks like the gauge
at Claiborne will just touch advisory threshold with the high
tide this evening. Further north in Kent County Maryland, it
appears that water levels will fall short with this evening`s
high tide. That being said, still increasing concern for tidal
flooding across most of the northeastern Chesapeake with high
tides on Saturday and Sunday. For now, have extended Coastal
Flood Advisory to cover the Saturday high tide cycle.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
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PA...Coastal Flood Advisory until 8 PM EDT this evening for PAZ070-
     071-106.
NJ...Coastal Flood Advisory until 5 PM EDT Sunday for NJZ016.
     Coastal Flood Advisory until 6 AM EDT early this morning for
     NJZ012>014-020>027.
     Coastal Flood Watch from 6 AM EDT this morning through Sunday
     afternoon for NJZ012>014-020>027.
     High Risk for Rip Currents through Sunday evening for NJZ014-
     024>026.
     Coastal Flood Advisory until 8 PM EDT this evening for
     NJZ017>019.
DE...Coastal Flood Advisory until 5 PM EDT Sunday for DEZ001.
     Coastal Flood Advisory until 6 AM EDT early this morning for
     DEZ002>004.
     Coastal Flood Watch from 6 AM EDT this morning through Sunday
     afternoon for DEZ002>004.
     High Risk for Rip Currents through Sunday evening for DEZ004.
MD...Coastal Flood Advisory until 11 PM EDT this evening for MDZ015-
     019-020.
MARINE...Small Craft Advisory until 6 AM EDT Monday for ANZ450>455.
-- End Changed Discussion --

&&

$$

SYNOPSIS...Deal/Franklin
NEAR TERM...Deal/Franklin/MPS
SHORT TERM...Deal/Johnson
LONG TERM...Deal/Johnson
AVIATION...Franklin/Johnson/MPS
MARINE...Franklin/Johnson/MPS
TIDES/COASTAL FLOODING...WFO PHI