279
FXUS61 KPHI 232003
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
403 PM EDT Mon Sep 23 2024

.SYNOPSIS...
High pressure over the Canadian Maritimes remains across the
Northeast and northern Middle-Atlantic region during the start
of the new week. By midweek, it will lift to the north and east
and off into the Atlantic. Low pressure approaches from the west
and drags a cold front towards the region by the middle of the week.
This system clears the region by the end of the week. High pressure
builds down from the north of the weekend and start of next week.

&&

.NEAR TERM /THROUGH TUESDAY/...
Cloudy to mostly cloudy conditions continue with some scattered
showers moving through the region. The greatest coverage has been
west of the I-95 corridor but we have seen some progression eastward
into central and southern New Jersey. PoPs are 40-60% for the Lehigh
Valley and southern Poconos with most of the rest of the area in the
20-40% range for the remainder of the afternoon and evening.

Expect coverage of showers to wane after sunset with loss of daytime
heating, but clouds should stay 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. Lows tonight are
forecast to be mainly in the mid 50s to near 60 in the I-95 corridor
(near 50 at higher elevations).

The story for Tuesday will be similar but with lower chances for
showers as high pressure centered to the northeast nudges back in.
Skies will be largely overcast to start the day but may become more
scattered in the afternoon before filling back in ahead of the next
system. High temperatures look to again be right around 70 degrees
except in the southern Poconos where low to mid 60s are
expected.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
Plenty of subtle changes in the upper air pattern with weak synoptic
systems bring a degree of uncertainty in the short term. The pattern
is becoming more amplified with a ridge off the East coast building
up into New England while a trough well to the west starts to close
off while capturing the tropical system approaching the Gulf Coast.
As these shifts take place, a weak surface low moves to the NW of
our area bringing a chance for showers Wed/Wed night. Our forecast
will have high chance/low likely pops for the wrn areas early Wed
which will spread east during the afternoon/overnight. Pops return
below slight chance for Thu. The areas N/W if I-95 will receive
the great totals (perhaps 1/4 to 1/2 inch) while S/E areas will
be more 1/10th to 1/4 inch (on average). Still, considering the
lack of rain lately, it will be welcome to most areas.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Looking towards the end of the week and into the weekend, the upper
air pattern looks to become more blocky across the Middle Atlantic
and Northeast. The previous upper low well to the NE gets reinforced
and remain across the northern Atlantic Ocean while a second cut-off
low develops over the the Midwest region. This Midwest low captures
what will be left of the tropical system and deepens as well. In
between, an upper ridge tries to build over our area with a surface
high to the north. The models are mildly dissimilar with regards to
how/when this happens. Overall the pops offered by the guidance is
low (mostly slight chance) and favors Delmarva and south NJ. The 12Z
GFS has a dry solution for the region with a stronger ridge while
the CMC brings moisture to the western areas Fri night/Sat. For now,
we`ll go along with the NBM guidance for the long term.

Temperatures will generally be above normal with highs in the
mid/upper 70s for the S/E areas and upper 60s/low 70s N/W. Lows will
favor the 50s N/W and 60s S/E.

&&

.AVIATION /20Z MONDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas...

Rest of Today...Primarily VFR expected, though ceilings, especially
this evening, will be very close to the MVFR threshold. Thus, MVFR
ceilings will be possible. KRDG and KABE have the highest risk to
see MVFR ceilings (though can`t rule it out at any of the TAF sites.
Rain showers possible, primarily at KRDG and KABE, but not expecting
any visibility restrictions. 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.

Tuesday...Primarily VFR with some MVFR mixed in, particularly during
the morning hours where ceilings start around 2000-3000 feet. Cloud
coverage looks to decrease somewhat for the afternoon which would
help raise cloud bases solidly above 3k ft. Easterly winds around 5-
10 kts. Moderate confidence.

Outlook...

Tue night thru Wed night... Scattered showers could bring lower
  CIGs/VSBYS at times. Mostly for KRDG/KABE. Patchy overnight
  fog possible too.

Thu thru Sat... Mostly VFR.

&&

.MARINE...
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...

We`ve extended the SCA into Wed for now, but it looks like perhaps
the end of the long-running SCA may follow for Wed night. The
sub-SCA may last thru Fri night with a possibility of another
SCA Sat or Sunday. Scattered showers Tue night thru Wed night.

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 Wednesday. The persistent onshore flow continues with
easterly winds of 10 to 20 mph along with 3 to 5 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. Some Coastal
Flood Advisories have been dropped as of this afternoon, while some
Coastal Flood Advisories remain in effect through the Tuesday
afternoon and evening high tide cycles.

Details as follows.

Dropped Coastal Flood Advisories for the southern Raritan Bay,
northern portions of the Atlantic coast of New Jersey, and southern
portions of the Atlantic coast for New Jersey. These counties
include Middlesex, Monmouth, southeast Burlington, Atlantic, coastal
Atlantic, Cape May, and Atlantic Coastal Cape May. Some spotty minor
coastal flooding could occur during the Tuesday morning/afternoon
high tide cycle, but flooding of advisory minor status is not
anticipated.

For Ocean county, coastal Ocean county, Sussex county (DE) and the
Delaware Beaches, the Coastal Flood Advisory is in effect until 6 pm
Tuesday to include the high tide cycle on Tuesday. This is mainly
for the back bays of Barnegat Bay as well as the Little Assawoman
Bay and the Indian River Inlet as water continues to be slow to
drain.

For Delaware Bay, the Coastal Flood Advisory is now in effect until
6 pm Tuesday to include the high tide cycle Tuesday for minor
coastal flooding.

For the tidal Delaware River, Coastal Flood Advisories remain in
effect until 10pm this evening for minor coastal flooding. A Coastal
Flood Advisory is unlikely to be needed for the Tuesday evening high
tide cycle.

For the northeastern shore of Maryland, Coastal Flood Advisories are
now in effect through Tuesday night/early Wednesday morning high
tide cycles for minor coastal flooding. A Coastal Flood Advisory may
be also needed for the Wednesday 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 7 PM EDT this evening for NJZ016.
     Coastal Flood Advisory until 6 PM EDT Tuesday for NJZ020-021-
     026.
     High Risk for Rip Currents through Wednesday evening for NJZ014-
     024>026.
     Coastal Flood Advisory until 10 PM EDT this evening for
     NJZ017>019.
DE...Coastal Flood Advisory until 7 PM EDT this evening for DEZ001.
     Coastal Flood Advisory until 6 PM EDT Tuesday for DEZ002>004.
     High Risk for Rip Currents through Wednesday evening for DEZ004.
MD...Coastal Flood Advisory until 5 AM EDT Wednesday for MDZ012.
     Coastal Flood Advisory until 2 AM EDT Wednesday for MDZ015-019-
     020.
MARINE...Small Craft Advisory until 6 PM EDT Wednesday for ANZ450>455.

&&

$$

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