495
FXUS61 KPHI 232243
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
643 PM EDT Thu May 23 2024

.SYNOPSIS...
A cold front move across the area this evening. The front will stall
to our south on Friday before lifting back north on Friday night as
a warm front. Another cold front moves through on Sunday with a
stronger system impacting the area on Monday into Tuesday. A
secondary cold front looks to cross the area on Wednesday into
Thursday.

&&

.NEAR TERM /THROUGH FRIDAY/...
640 PM...As of early this evening, a weak cold front remains
situated over eastern PA then extending south and west into
western Maryland. Near and south of this front there have been
some new storms that have formed over northern Virginia into
western Maryland within the past couple hours and some of these
have been severe producing large hail. ML CAPES in the vicinity
of these storms as well as over the eastern MD shore are around
1000 j/kg with deep layer shear around 35 to 40 knots. So this
is supportive of severe weather. The limiting factors though are
that the forcing is not very strong and also that instability
will be generally on the wane as we go through the evening and
lose the daytime heating. The upshot is that we continue to
mention the chances for isolated to scattered thunderstorms this
evening over Delmarva and far southern NJ (POPs generally 20 to
30 percent) but think that any severe weather that occurs in
these areas should be pretty isolated. The Storm Prediction
Center continues to highlight a MARGINAL threat for severe
weather here with the main threats being large hail and damaging
winds.

The convection should tend to wane overnight, however a
trailing shortwave may result in some showers or thunderstorms
early Friday morning for Delmarva, southern New Jersey and
perhaps into parts of southeast Pennsylvania. The wind will be
light to calm tonight and if clouds clear enough for a time,
patchy fog will be possible.

As we go through Friday, a weak cold front should be stalling across
parts of Delmarva. The placement of this front along with a trailing
piece of energy may continue to support some showers or thunder
across our southern areas to start the morning. The cloud cover will
clearing from the northwest, with some mid to high level clouds
lingering the longest for our Delmarva to southeastern New Jersey
areas. As the low-level flow turns more westerly in the wake of the
front, drier air will arrive and dew points are forecast to drop
into the 50s for much of the area. The dew points look to remain in
the 60s however across Delmarva to southeastern New Jersey. It will
be a warm day with much of the area getting into the 80s, although
with lighter flow expected a sea breeze should develop resulting in
cooling closer to the coast.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
Tranquil weather will continue into Friday night with clear skies
and light winds initially. We should be able to radiate pretty well
leading to some patchy fog development over Delmarva and southern
New Jersey. However, clouds will increase from south to north later
in the night as the stalled front begins to lift back north across
the area. This should limit the amount of cooling late, so expecting
lows in the mid 50s to lower 60s.

For Saturday, the warm front will lift completely north of the area
as the main low pressure system tracks across the Great Lakes.
Saturday morning likely stays dry however, as we progress through
the afternoon, the chance for showers and thunderstorms increase
from west to east. For locations along the shore, precip should hold
off entirely until Saturday evening, although it will be a mix of
sun and clouds most of the day. This system will be a rather quick
mover so while Saturday night does appear to be wet especially north
and west, all precipitation should end by Sunday morning. The region
should dry out on Sunday as the front now looks to stall to our
north and west, resulting in sunny skies in the afternoon with some
fair weather clouds. Slight chance of a shower in the higher
elevations which remains closer to the stalled boundary. Aided by
warm air advection, highs on Saturday and Sunday should reach into
the low to mid 80s with cooler temps along the coast. Saturday night
lows will be in the mid 50s to low 60s.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
Beyond Sunday, the weather pattern becomes unsettled as a stronger
low pressure system develops back over the central CONUS. Strong PVA
will move over the region Monday with stronger cold front crossing
the area Monday night into Tuesday. This will lead to widespread
shower activity across the region. WPC has included a Marginal risk
for Excessive Rainfall and CIPS analog guidance is highlighting the
potential for severe weather across the Delmarva (10-15% chance) on
Monday and across the entire area on Tuesday (10% chance). Will
continue to monitor and focus attention on this time period of
Monday afternoon through Tuesday. After the cold front passes,
unsettled weather continues to be the theme thanks to several
waves/impulses aloft passing through the week.

Temps for the workweek should be fairly seasonable with highs in the
70s through Wednesday, before falling back into the 60s by
Thursday.

&&

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

Tonight...VFR overall, however a few showers and thunderstorms will
be around this evening which could result in local and brief
sub- VFR conditions. Localized fog cannot be ruled out
overnight. Winds becoming light and variable to calm overall.
Low confidence.

Friday...VFR overall. A few showers or a thunderstorm possible early
in the morning. Light and variable winds becoming northwest around 5
knots, then becoming west. A sea breeze may result in winds becoming
south or southeast at KACY and KILG in the afternoon. Moderate
confidence.

Outlook...

Saturday through Saturday night...VFR during the day, likely
becoming sub-VFR at night. Showers and thunderstorms late in the day
into the evening.

Sunday...VFR. No significant weather expected.

Sunday night through Tuesday...Sub-VFR conditions probable with a
chance of showers and thunderstorms especially on Monday into
Monday night.

&&

.MARINE...
The conditions are expected to remain below Small Craft Advisory
criteria through Friday, however a few gusty thunderstorms will be
possible this evening mainly across the southern coastal waters
including Delaware Bay.

Outlook...

Friday night through Tuesday...No marine headlines expected. Winds
will occasionally gust up to 15-20 kt with seas around 2-4 feet. A
chance for showers is expected on Saturday night with a chance for
showers and thunderstorms Monday into Tuesday. Marine fog is also
possible on Saturday morning.

Rip Currents...

S to SW winds will average 5 to 10 mph today along with
breaking waves around 2 feet. There is a LOW risk for the
development of dangerous rip currents at NJ and DE beaches for
today. However, some showers and thunderstorms will be around.

On Friday, winds will once again be out of the S to SW at 5 to
10 mph with breaking waves of 1 to 2 feet. There is a LOW risk
for the development of dangerous rip currents at NJ and DE
beaches. Although there is a slight chance for showers,
thunderstorms are not expected.

&&

.TIDES/COASTAL FLOODING...
Astronomical tides will be elevated this week with a Full Moon
occurring today, May 23. Spotty minor coastal flooding will be
possible, especially for the back bays, around the times of the
evening high tide cycle, which will be the higher of the two
tide cycles, going into the end of this week.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...None.

&&

$$

SYNOPSIS...Deal/DeSilva
NEAR TERM...Fitzsimmons/Gorse
SHORT TERM...Deal/DeSilva
LONG TERM...Deal/DeSilva
AVIATION...DeSilva/Gorse
MARINE...DeSilva/Gorse
TIDES/COASTAL FLOODING...