217
FXUS61 KPHI 200802
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
402 AM EDT Fri Sep 20 2024

.SYNOPSIS...
An area of low pressure will continue to spin off of the east
coast while high pressure remains across eastern Canada, nosing
its way into the region into 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 TONIGHT/...
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.

Some patchy ground fog this morning will lift and dissipate
shortly after sunrise due to heating of the day. Mostly sunny
skies this morning will give way to partly cloudy skies this
afternoon and evening.

Although some light rain showers will rotate around the low and
back towards the mainland, they will be isolated, so will keep
PoPs capped at slight chance, and primarily for this afternoon.
QPF will be minimal.

Skies clear out tonight, and with light onshore flow, patchy
fog is possible once again.

Highs today will be mild with highs some 5 degrees or so above
normal, topping off in the upper 70s to low 80s, and lows
tonight will be in the 50s to low 60s.

&&

.SHORT TERM /SATURDAY THROUGH 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 in the day, 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. As the day shift
mentioned yesterday, its 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 THURSDAY/...
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 /07Z FRIDAY THROUGH TUESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Today...Local ground fog with restrictions as low as IFR through 12Z
or so. VFR otherwise. E to NE winds 5 to 10 kt. High confidence.

Tonight...VFR expected, however, patchy fog may result in MVFR or
lower conditions. LGT/VRB winds. Low confidence on development of
fog.

Outlook...

Friday night-Saturday...VFR conditions expected.

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 today and
tonight, primarily for 4 to 6 ft seas. However, there may be some
25+ kt gusts this afternoon. Otherwise, NE winds will average 15 to
20 kt.

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

Outlook...

Friday 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...
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.

Coastal Flood Advisories are posted for the New Jersey coast,
Delaware Coast, and part of the Delaware Bay (Cumberland County
in New Jersey and Kent County in Delaware) as at least minor
tidal flooding is expected around high tide through the end of
the weekend. Some guidance indicates moderate flooding may occur
for some locations as early as the Friday morning high tide
cycle. However, confidence in this remains low at this time;
will stick with the advisory for now. A short-fused upgrade may
occur during the next update. Confidence is better for moderate
coastal flooding to occur with high tide cycles this weekend.
Have issued a Coastal Flood Watch as a result to cover the
Saturday and Sunday morning high tide cycles.

For the tidal Delaware River, in general, it looks like water
levels will stay just below advisory thresholds, but will be
watching trends closely.

For the northeastern shore of Maryland, am getting increasingly
concerned that there will be minor flooding over the weekend.
Latest high tide cycle was considerably higher than most
guidance. Will watch trends overnight to see if this low bias
continues.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...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.
DE...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...None.
MARINE...Small Craft Advisory until 6 AM EDT Monday for ANZ450>453.
     Small Craft Advisory from 8 AM this morning to 6 AM EDT Monday
     for ANZ454-455.

&&

$$

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