Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 252025
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
425 PM EDT Mon Mar 25 2024

.SYNOPSIS...
The base of high pressure extending down from eastern Canada
will remain along the East Coast into Tuesday night. Low
pressure tracking along southern Canada will drag a cold front
through the region Tuesday night, and then the front becomes
nearly stationary along the coast. Low pressure develops over
the Gulf of Mexico and tracks along the coast Thursday and
Thursday night before moving out to sea on Friday. A weak
clipper system passes through on Saturday.

&&

.NEAR TERM /THROUGH TUESDAY/...
High pressure continues across eastern Canada with a strong
ridge across New England and the northern Middle Atlantic areas.
Fair weather will continue this evening with mostly clear skies
early. After midnight, clouds will increase over the area,
roughly southeast to northwest as onshore low-level flow
continues and the atmosphere moistens up. No rains are expected
but perhaps a patch of drizzle or two near the shore is
possible. Low temperatures will mostly be in the mid/upper 30s
for the coastal plain and upper 20s to low 30s for the NW-most
areas. Winds will be East at 5 to 10 mph.

For Tuesday, the onshore flow aloft will continue so there will
be mostly cloudy skies across the area. The clouds and breeze
from the East/Northeast will keep temperatures cool for late
March with highs mostly upper 40s or low 50s. Winds will be 10
to 15 mph with gusts around 25 mph especially around the shore
areas.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
A weak cold front approaches Tuesday night and works its way
through the region late at night and into Wednesday morning. The
front actually washes out and becomes nearly stationary along
the coast on Wednesday, and there is not much in the way of
colder or drier air behind it, but it will touch off some
showers with its passage late at night and into Wednesday
morning.

Another area of low pressure will organize and develop over the
Southeast U.S. on Wednesday and will track along the coast late
Wednesday and Wednesday night. Rain moves into the region after
midnight, with with an approaching upper low, and interaction
with the coastal front, the low will intensify during the day
Thursday. Rain becomes moderate to heavy at times, especially
over Delaware and New Jersey, on Thursday, and another 1.5
inches or so of QPF will fall.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Coastal low pressure off the Mid-Atlantic coast Thursday
evening will track to the east-northeast during the overnight
hours and will be offshore by Friday morning. The low then
continues to track out towards the Canadian Maritimes on Friday.
Rain tapers off through the night, and then a gusty northwest
flow sets up on Friday as a tight pressure gradient develops
between the departing low and high pressure building over the
Gulf Coast states and Southeast.

A weak clipper-like system quickly passes through the Northeast
and Mid-Atlantic over the weekend. For now, will generally
carry slight chance to low end chance PoPs for Saturday and
Saturday night. High pressure then noses in from the north and
west on Sunday, but another storm system will be gearing up to
take a shot at the Northeast and Mid-Atlantic for the start of
the new work week.

Temperatures during this period will generally be near or a
couple of degrees above normal.

&&

.AVIATION /21Z MONDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas...

Tonight...VFR for the evening and then an increase in low
clouds expected. These clouds will generally advance from the
near-ocean areas and move W/NW overnight. CIGS likely MVFR, but
there is a possibility of CIGS lowering to IFR towards dawn.
Medium confid with timing but low confid with any possible IFR
occurring. E winds around 10 knots.

Tuesday...Low clouds expected to remain over the area much of
the day. Again, probably mostly MVFR (010-020), but IFR possible
especially near the shore (KACY). E or NE winds 10 to 15 kts
with gusts closer to 20 kts KACY. Medium confid overall.

Outlook...

Tuesday night through Saturday...Overall, periods of sub-VFR
conditions, mostly Tuesday night through Thursday night, first
in fog and stratus Tuesday night, and then in periods of
moderate to heavy rain late Wednesday through Thursday night.
VFR returns on Friday. Scattered SHRA may result in brief sub-
VFR conditions Saturday. Onshore flow Tuesday night through
Thursday night, generally 10 kt or less, then gusty NW winds
develop Thursday night through Saturday.

&&

.MARINE...
Large storm well offshore isn`t in a hurry to leave the scene
and will meander around thru Tuesday. It will continue to
produce enhanced winds and seas tonight and Tuesday. Th SCA flag
for the ocean will continue thru Tuesday and the lower Delaware
Bay SCA will end during the overnight period. By then, gusts
for the lower Bay should be below 25 kts for the most part. Fair
weather tonight and Tuesday.

Outlook...

Tuesday night through Saturday...SCA conditions continue
Tuesday night and into at least Wednesday due to elevated seas.
A storm will develop and lift along the coast Wednesday night
through Thursday night, departing on Friday. Strong NW winds
develop Thursday night and continue into Saturday. SCA
conditions expected with marginal gales possible on Friday.

&&

.TIDES/COASTAL FLOODING...
A low pressure system lingering well off the coast will result
in an extended duration of long period swells and rough surf
impacting the Atlantic coast. Surge values of 2-3 feet are
currently forecast by tonight. Confidence in flooding is not
especially high given trends in the forecast compared to
observations, as the last two high tide cycles verified low, but
increasing onshore fetch and the full moon may result in a
ramp-up of water levels.

Thus, still think we likely have widespread MODERATE flooding
along the oceanfront and Delaware side of the Delaware Bay
tonight and Tuesday. Coastal Flood Warnings remain in effect as
previously issued. Some guidance has MODERATE flooding lingering
several cycles, but for now have cut off the warning at 2 PM
Tuesday.

Widespread MINOR flooding still looks likely across the
Cumberland County, NJ side of the Delaware Bay and the Salem
County, NJ and New Castle County, DE shores of the upper bay by
this evening`s high tide. Therefore, Coastal Flood Advisories
remain in effect through mid-afternoon Tuesday as well with
widespread MINOR flooding expected with each successive cycle.

Spotty minor coastal flooding is possible along the tidal
Delaware River and the eastern shore of Maryland, but
significant flooding not anticipated.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...Coastal Flood Advisory from 11 PM this evening to 3 PM EDT
     Tuesday for NJZ016.
     Coastal Flood Warning until 2 PM EDT Tuesday for NJZ020-
     022>027.
     Coastal Flood Warning until 2 PM EDT Tuesday for NJZ012>014.
     Coastal Flood Advisory until 2 PM EDT Tuesday for NJZ021.
DE...Coastal Flood Advisory from 11 PM this evening to 3 PM EDT
     Tuesday for DEZ001.
     Coastal Flood Warning until 2 PM EDT Tuesday for DEZ002>004.
MD...None.
MARINE...Small Craft Advisory until 2 AM EDT Tuesday for ANZ431.
     Small Craft Advisory until 6 AM EDT Wednesday for ANZ450>455.

&&

$$

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


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