455
FXUS61 KPHI 110143
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
943 PM EDT Fri May 10 2024

.SYNOPSIS...
A wave of low pressure offshore moves away overnight. Weak high
pressure arrives for Saturday before another low moves through
Saturday night and Sunday. High pressure builds south of the
Mid-Atlantic region Sunday night into Monday. Another area of
low pressure may affect the area with more unsettled weather by
the middle of next week.

&&

.NEAR TERM /THROUGH SATURDAY/...
The offshore low will continue to move away overnight and the
upper trough to the west will swing through. Showers and drizzle
are rapidly dwindling as drier air arrives aloft. Fog is
possible if breaks develop in the overcast, which is looking
more likely based on latest guidance. That said, given the
improved cloud cover forecast, odds of seeing the aurora
borealis from the powerful geomagnetic storm in progress have
increased. By morning, lows will drop into the low 40s up
across the N/W areas while mid/upper 40s will be for the other
areas. Winds will remain Northwest to East at 5 to 10 mph.

For Saturday, a more tranquil weather day is expected with weak
high pressure building in. There may still be some low clouds
or fog across the area early, but thru the morning partly sunny
skies will develop across most areas. By afternoon, the sun will
mix with clouds at times. A couple showers may spill over the
western areas by late afternoon. High temperatures will be below
normal with high only in the low/mid 60s for most spots. Highs
in the 50s will be across the higher elevations of the Poconos.
Winds will be Northeast at 5 to 10 mph.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
A digging trough moving through the Great Lakes and an
associated wave of low pressure at the surface will approach and
push through Saturday Night into Sunday. Expecting more rain
and a relatively dreary Sunday. Some elevated instability works
in, especially over Delmarva, so can`t rule out a rumble of
thunder, though not expecting any severe weather. Rainfall
amounts from a tenth to a half an inch are expected, with areas
north and west of the Philadelphia metro getting into the upper
end of that spectrum. It will be quite raw out with periods of
rain and temperatures in the upper 50s/low 60s for Mother`s Day.

We begin to dry out on Sunday night as the trough moves
offshore and ridging builds in from the west. Expecting a spread
of 40s for overnight lows to close out the weekend.

A nice start to the week is expected with a broad area of high
pressure working in. Temperatures moderate back to near-normal
levels for mid-May, with low to mid 70s expected for most. The
exception being the southern Poconos and along the coast, where
highs will stay in the 60s. Skies will be mostly sunny with some
passing clouds at times.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
Long term period will be marked by a couple systems moving
through over the work week, with temperatures hovering near
normal for mid- May. Looking at some of the NAEFS ensemble
probabilities and percentiles, the two main systems next week
look rather unimpactful at this time, just bringing some rain to
the region. Flooding and severe potential looks quite low
currently.

Ridging moves offshore Monday night with a shortwave moving
across the Ohio Valley towards the Mid-Atlantic. An area of low
pressure will take a similar track, eventually moving over or
just south of the region on Tuesday Night. Rain chances increase
by midday, with both deterministic and ensemble guidance
showing the bulk of the rain coming in the overnight hours of
Tuesday. There could be some embedded thunder as well.

Showers could linger through the day on Wednesday but things
try to turn drier Wednesday night into Thursday as a ridge
builds in. The tranquil weather does not last for long as
another system moves in for the end of the week.

&&

.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas...

Tonight...Conditions mostly MVFR just before 0Z with slow
improvement expected over the next few hours as rain and drizzle
diminish. However, not a strong push of dry air, so where cigs
break and winds go light/vrb, could get patchy fog. Low confid
overall.

Saturday... Any lingering low clouds/fog early will diminish
12Z/13Z followed by VFR conditions. Clouds will increase during
the afternoon. Light winds will become Southeast at 5 to 10
knots during the afternoon. Low/medium confid.

Outlook...

Saturday Night through Sunday Night...MVFR/IFR conditions
expected with low ceilings and reduced visibility with periods
of rain moving through.

Monday through Monday Night..VFR. No significant weather.

Tuesday...VFR to start but sub-VFR conditions likely (60-70%)
later in the day as showers move in.

Tuesday Night through Wednesday...Sub-VFR conditions expected
with showers. Chance of thunderstorms (15-25%) Tuesday night
into Wednesday.

&&

.MARINE...
Cancelled SCA for Delaware Bay with wind gusts dropping below
25 kts. The SCA for the ocean continues Saturday with seas
remaining above 5 ft thru that period. Precip ending this
evening with patchy fog possible overnight. Fair weather
expected for Saturday.

Outlook...

Saturday Night through Monday...No marine headlines expected.

Monday Night through Wednesday...SCA conditions possible
(30-40%) as wind gusts get near 25 kt. Seas will get near 5 feet
on Wednesday.

&&

.TIDES/COASTAL FLOODING...
The new moon occurred Tuesday, May 7th, and this is resulting
in high astronomical tides. An onshore has developed and will
remain thru tonight. While the astronomical tides will be
gradually lowering as we get farther away from the new moon, the
onshore will increase the surge values at least some. With the
peak onshore flow leading up to tonight`s high tide cycle,
guidance continues to indicate the threat for moderate tidal
flooding for portions of Atlantic coastal New Jersey and
Delaware, as well as Delaware Bay with the high tide cycle
tonight into early Saturday morning high tide cycle. With
increased confidence of a long duration of moderate to strong
onshore flow through the day today and water levels/surge values
continuing to run high with the latest high tide cycle last
night into early this morning, the Coastal Flood Warning for
tonight`s high tide has been expanded to include all areas
previously covered by the Coastal Flood Watch. Spotty minor
coastal flooding will occur with todays (lower) high tide today
within the Warning area.

Outside of the Warning area, in adjacent areas of the Atlantic
coast of New Jersey, Delaware Bay, and the tidal Delaware River,
another round of widespread minor coastal flooding is expected
with the high tide cycle tonight into early Saturday morning.
Therefore, another Coastal Flood Advisory has been issued for
these areas for the tonight into early Saturday high tide cycle.

The high tide cycle tonight looks to be the peak of the coastal
flooding impacts area-wide, but additional minor coastal
flooding is forecast with the evening/overnight high tide
Saturday night into early Sunday.

Flooding is not expected at this time for our Maryland zones
along the Chesapeake through Saturday.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Coastal Flood Advisory from 2 AM to 7 AM EDT Saturday for
     PAZ070-071-106.
NJ...Coastal Flood Advisory until 4 AM EDT Saturday for NJZ016.
     Coastal Flood Warning until 4 AM EDT Saturday for NJZ020>027.
     Coastal Flood Advisory until 3 AM EDT Saturday for NJZ012>014.
     Coastal Flood Advisory from 2 AM to 7 AM EDT Saturday for
     NJZ017>019.
DE...Coastal Flood Advisory until 4 AM EDT Saturday for DEZ001.
     Coastal Flood Warning until 4 AM EDT Saturday for DEZ002>004.
MD...None.
MARINE...Small Craft Advisory until 6 PM EDT Saturday for ANZ450>455.

&&

$$

SYNOPSIS...AKL/Fitzsimmons/OHara
NEAR TERM...OHara/RCM
SHORT TERM...Hoeflich
LONG TERM...Hoeflich
AVIATION...Hoeflich/OHara/RCM
MARINE...Hoeflich/OHara/RCM
TIDES/COASTAL FLOODING...