805
FXUS61 KPHI 201733
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
133 PM EDT Fri Sep 20 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 and Sunday,
before a stronger low pressure system possibly impacts the area
by the middle of next week.

&&

.NEAR TERM /THROUGH SATURDAY/...
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. Clouds will be most prevelant closer to
the coast this afternoon otherwise it will be a mostly sunny
and nice day.

Mainly clear tonight, and with light onshore flow, patchy fog
is possible once again. Saturday will be another mostly dunny
day as high pressure remains ridged over the eastern US.

&&

.SHORT TERM /SATURDAY 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. Late Saturday, a
an area of PVA starts pushing in creating enough lift across our
western counties to see some showers develop. It doesn`t seem
to be anything significant however there`s a moderate (30-40%)
chance of showers developing over central PA. It`s not a frontal
passage but rather some synoptic lift that causes the showers
so rainfall doesn`t look to overspread the entire forecast area.
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 /SUNDAY THROUGH FRIDAY/...
High pressure returns to start the work week bringing dry
weather back to the region. However the dry weather may not
last long as current guidance suggests 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 (40-50%) 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.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

This afternoon...VFR. NE to E winds 5 to 10 kt.

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

Saturday...VFR. NE to E winds 5 to 10 knots.

Outlook...


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

Sunday...Generally VFR with MVFR possible during the morning,
improving to VFR.

Sunday night-Monday...VFR conditions expected.

Monday night-Tuesday...VFR prevailing with MVFR or IFR
possible in showers.

&&

.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 due to seas.

Monday-Tuesday...Small Craft Advisory conditions likely
continue due to seas.

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
today and Saturday, and possibly for Sunday as well. NE winds will
range from 15 to 20 mph with gusts up to 25 mph along with 4  to 6
ft breaking waves both today and Saturday.

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

&&

.TIDES/COASTAL FLOODING...
What has chaged: Given current tidal departures, there is
increasing concern of minor tidal flooding on the tidal portions
of the Delaware River and on some portions of the Northeastern
Chesapeake Bay. A coastal flood advisory has been issue for some
of these locations for the high tide later today.

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
portions of our area. Moderate tidal flooding may occur for
portions of our area this weekend.

No changes in headlines for the Atlantic coast and Delaware Bay.
We are in the midst of the current high tide cycle and forecast
looks on track. Still increasing confidence in moderate coastal
flooding with high tide cycles this weekend. Will determine if
the watch needs to be updated to a warning as guidance comes in
through the day.

For the tidal Delaware River, there is increasing concern for
widespread minor flooding, starting with the high tide this
afternoon/evening. For now, have only issued the coastal flood
advisory to cover this high tide as will have better confidence
on future high tides once we see departures with today`s high
tide.

For the northeastern shore of Maryland, it looks like the guage
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.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Coastal Flood Advisory until 7 PM EDT this evening for PAZ070-
     071-106.
NJ...Coastal Flood Advisory until 3 PM EDT this afternoon for
     NJZ016.
     Coastal Flood Advisory until 6 AM EDT Saturday for NJZ012>014-
     020>027.
     Coastal Flood Watch from Saturday morning through Sunday
     afternoon for NJZ012>014-020>027.
     High Risk for Rip Currents through Saturday evening for NJZ014-
     024>026.
     Coastal Flood Advisory until 7 PM EDT this evening for
     NJZ017>019.
DE...Coastal Flood Advisory until 3 PM EDT this afternoon for
     DEZ001.
     Coastal Flood Advisory until 6 AM EDT Saturday for DEZ002>004.
     Coastal Flood Watch from Saturday morning through Sunday
     afternoon for DEZ002>004.
     High Risk for Rip Currents through Saturday evening for DEZ004.
MD...Coastal Flood Advisory from 5 PM this afternoon to 8 PM EDT
     this evening for MDZ015-019-020.
MARINE...Small Craft Advisory until 6 AM EDT Monday for ANZ450>455.

&&

$$

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