663
FXUS61 KPHI 100009
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
809 PM EDT Thu May 9 2024

.SYNOPSIS...
Weak high pressure will remain across the northern Middle Atlantic
region this evening. After that, several waves of low pressure
affect our area with the unsettled patterned continuing from
later tonight through Sunday. High pressure builds south of the
Mid-Atlantic region Sunday night into Monday. More unsettled
weather may impact our area next week.

&&

.NEAR TERM /THROUGH FRIDAY/...
Low pressure well to the west is moving rather quickly along
the front (to our south) and will bring poorer conditions for
as we head into the overnight. Spotty rain has already
overspread the region. More rains will develop and move across
the region as the evening continues and then become steadier
overnight. Low pressure will move offshore by Friday morning and
a NE flow around the N side of the low will bring low clouds
and rains to the region late tonight.

For Friday, the low will continue to move offshore, but an
upper trough and lingering low level moisture will keep plenty
of clouds and rains across the area Friday.

For the evening update, main change was more of the flavor vs.
substance... instead of showers, went with occasional/periods of
rain and drizzle, given the cool onshore flow and overall lack
of convection. NBM thunder probs do have some slight chances
across southern areas, so did include a slight chance of thunder
tonight and tomorrow as the main wave moves by, but its only
slight and will be elevated above the cool marine layer.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
Unsettled weather will continue through Sunday with a brief
reprieve during the day on Saturday. PoPs remain in the 35-45
percent range Friday night as the low continues to move offshore
but by early Saturday, the low looks to be far enough away that
conditions should be mostly dry regionwide. Lows Friday night
will be mainly in the mid-upper 40s and highs Saturday will warm
back into the low 60s.

By later in the day Saturday though, the next wave of low
pressure will arrive out of the Great Lakes, increasing chances
for showers, particularly northwest of the I-95 urban corridor.
Showers continue to move into the region Saturday night (PoPs
45-55 percent) with lows again in the mid-upper 40s. Chances for
rain will linger into Sunday as well with highs once again in
the low 60s.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
A brief period of dry weather is expected beginning Sunday
night and continuing into Monday as high pressure briefly builds
to the south of the Mid Atlantic region. This dry weather will
only be brief as chances will begin to increase Tuesday night
into Wednesday as a storm system approaches from the southwest.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas...

Rest of Tonight...Rain/drizzle becoming more widespread and
steadier with some patchy fog likely as well. Cigs lowering to
MVFR through the evening with IFR cigs likely toward morning.
East winds around 10 knots. Moderate confidence.

Friday...Rain/drizzle continuing with conditions remaining IFR
likely through at least the first half of the day with some
improvement to low MVFR possible by afternoon. East to northeast
winds around 10 knots with some gusts to 15-20 knots. Moderate
confidence.

Outlook...

Friday night-Sunday...Sub-VFR conditions probable (50-60
percent chance) at times through the period with chances (40-50
percent) for showers.

Sunday night-Tuesday...VFR conditions expected through Monday.
Sub- VFR conditions with chances for showers return late
Tuesday.

&&

.MARINE...
Latest guidance continues to advertise strong easterly flow
developing as wave of low pressure passes to the south late
tonight and Friday. In fact, its now advertising borderline
gales over the NJ ocean zones. Did not go quite that far, but
did increase winds to just below gales and extend time of SCA to
begin a little earlier overnight. Also added SCA to Delaware Bay
during peak winds Friday morning-midday. Will let mid-shift re-
evaluate any need for upgrade to gales.

Outlook...

Friday night and Saturday...Small Craft Advisory extended for
Atlantic Ocean coastal waters through Saturday. Seas of 5-6 feet
expected with winds gusting 20-25 knots. Sub- SCA conditions on
the Delaware Bay. Sub-SCA conditions return Saturday night.

Sunday through Tuesday...Overall, mainly sub-SCA conditions
expected through Monday. Stronger winds may bring SCA conditions
back late Monday into Tuesday.

&&

.TIDES/COASTAL FLOODING...
The new moon occurred Tuesday, May 7th, and this is resulting
in high astronomical tides. As a front settles to our south, an
onshore flow will develop and strengthen some through the end
of the week, peaking Friday into Friday night. While the
astronomical tides will be gradually lowering as we get farther
away from the new moon, the onshore flow should increase the
surge values at least some. With this combination, widespread
minor tidal flooding is again expected with the high tide
tonight into early Friday morning for the Atlantic coastal
zones, the Delaware Bay, and the tidal Delaware River. As a
result, the Coastal Flood Advisories remain in effect for these
areas.

With the peak onshore flow leading up to the Friday night high
tide cycle, guidance continues to support potential for
moderate tidal flooding for portions of Atlantic coastal New
Jersey and Delaware, as well as Delaware Bay with the Friday
night to early Saturday morning high tide cycle. The Coastal
Flood Watch was expanded to include southeastern Burlington and
Ocean Counties. As of the 5 PM Thursday forecast update, our
confidence is highest that coastal Sussex (DE) and Cape May
Counties are the most likely locations to see moderate coastal
flooding impacts Friday night, thus the Coastal Flood Watch was
upgraded to a Warning for those two counties.

Elsewhere within the Coastal Flood Watch area, there is
somewhat lower confidence that moderate tidal flooding impact
will be experienced. Thus, the Watch remains in effect.
Regardless, widespread minor tidal flooding is expected within
the Watch area and adjacent areas of the Atlantic coast of New
Jersey, Delaware Bay, and the tidal Delaware River with the
Friday night to early Saturday morning high tide cycle.
Examination of tonight`s observed water levels and surge values
and additional guidance will be used to determine which areas
will need to be upgraded to a warning or to an advisory for
Friday night.

The Friday night high tide cycle 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 1 AM to 6 AM EDT Friday for PAZ070-
     071-106.
NJ...Coastal Flood Advisory until 3 AM EDT Friday for NJZ016.
     Coastal Flood Advisory until 2 AM EDT Friday for NJZ012>014-
     020>027.
     Coastal Flood Watch from Friday evening through late Friday
     night for NJZ020>022-025>027.
     Coastal Flood Warning from 8 PM Friday to 4 AM EDT Saturday
     for NJZ023-024.
     Coastal Flood Advisory from 1 AM to 6 AM EDT Friday for
     NJZ017>019.
DE...Coastal Flood Advisory until 3 AM EDT Friday for DEZ001.
     Coastal Flood Advisory until 2 AM EDT Friday for DEZ002>004.
     Coastal Flood Watch from Friday evening through late Friday
     night for DEZ002.
     Coastal Flood Warning from 8 PM Friday to 4 AM EDT Saturday
     for DEZ003-004.
MD...None.
MARINE...Small Craft Advisory from 6 AM to 1 PM EDT Friday for ANZ430-
     431.
     Small Craft Advisory from midnight tonight to 6 PM EDT
     Saturday for ANZ450>453.
     Small Craft Advisory from 6 AM Friday to 6 PM EDT Saturday for
     ANZ454-455.

&&

$$

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