119
FXUS61 KPHI 231546
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
1146 AM EDT Thu May 23 2024

.SYNOPSIS...
A cold front will approach today before crossing the area this
evening. The front will stall to our south on Friday before
lifting back north on Saturday as a warm front. Another cold
front moves through on Sunday, with a stronger system impacting
the area on Monday into Tuesday. High pressure returns on
Wednesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1140 AM, the organized area of thunderstorms has moved
well northeast of our area. The air mass has become more stable
now in the wake of that convection. Some showers however are
making their way northeastward from the Baltimore area. A few
thunderstorms may also develop ahead of this where the air mass
was not really overturned from the earlier convection. Adjusted
the PoPs quite a bit based on radar trends and guidance,
delaying a thunder mention for much of the area for a while.

Several reports of wind damage in portions of the Lehigh Valley
with an intense storm. The damage looks like it was produced by
severe straight-line winds (downbursts/microbursts). Another
severe downburst/microburst looked to have occurred earlier in
portions of Sussex County, NJ.

Otherwise, as the front arrives and bisects the region, it will
become quasi-stationary near and just south of the I-95
corridor and gradually sag southward through the afternoon and
evening. At this time, another mid level shortwave shifts
overhead to provide some additional forcing along this front.
Some high-res guidance depicts a second round of scattered
showers and thunderstorms developing and riding along the front.
Depending on how worked over the environment will be after the
morning cluster of storms and where any residual outflow
boundaries set up, we could see some strong to marginally severe
thunderstorms across the Delmarva and southern NJ with this
second round. Locally damaging winds will be the main hazard
throughout the day, especially where storms are able to become
more organized such as in a cluster or a line segment.

Any showers and thunderstorms are expected to be weakening and/or
moving offshore tonight as the cold front shifts to our east,
though portions of southern NJ and the Delmarva could see
scattered showers linger through daybreak early Friday morning.
Further north and west, drier air will gradually filter in
throughout the overnight period. Patchy fog cannot be ruled out,
especially where rain occurs and if the cloud cover clears
enough.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
Friday continues to look like a pleasant day with warming
temperatures into the mid 80s with 70s along the shore due to
the sea breeze. A cold front will move offshore and stall south
of the area on Friday. A few residual showers may linger along
the shore in the morning but for the most part all precipitation
should be over. Skies will clear behind the front as dewpoints
fall back into the 50s. The pleasant and quiet weather will
continue into Friday night with clear skies and light winds. We
should be able to radiate pretty well initially leading to some
patchy fog development over DelMarVa where the heaviest rain is
forecast to fall on Thursday. Clouds will increase from south to
north later in the night which should limit the amount of
cooling late, and thus the expansion of fog across the northern
portions of the forecast area.

For Saturday, the stalled boundary to our south will begin to
lift back northward across the area as a warm front with the
main low pressure system tracking across the Great Lakes. Early
morning on Saturday 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 may hold off entirely until Saturday evening, although it
will be pretty cloudy most of the day. This system will be a
rather quick mover so while Saturday night does appear to be
wet, all precipitation should come to an end by early Sunday.
Aided by warm air advection, highs on Saturday should reach
again into the low to mid 80s despite cloud cover with cooler
temps along the coast. Saturday night lows will be in the mid
50s to low 60s.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
After precip wanes on Sunday morning, a weak cold front will
pass through the area, however the front will be slowing down
and stalling either over or again just south of the area. Sunday
for now does appear to be mostly dry behind the front with
partial sunshine. 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 Slight risk for Excessive
Rainfall, and CIPS analog guidance is highlighting the potential
for severe weather with between a 15-30% chance of severe
weather across PA and 10-15% chance for DelMarVA and NJ. 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 low to mid 80s Sunday followed more seasonable 70s
through the week. Lows should be falling into the 60s each
night.

&&

.AVIATION /16Z THURSDAY THROUGH MONDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas...

This afternoon...Some showers around along with a few
thunderstorms, which will locally result in sub-VFR conditions
for a time. Any additional thunderstorms should occur after 18z.
Areas of north-northwest winds around 10 knots are anticipated
to become west and southwest near 5 knots. Low confidence.

Tonight...Some lingering showers and thunderstorms could result
in brief sub-VFR conditions early in the evening, mainly for
KMIV/KACY, but coverage should diminish later into the nighttime
hours. VFR conditions overall overnight, though KACY looks to
see lower visibilities and ceilings as showers will linger
around here a bit longer. That said, some patchy fog cannot be
ruled out. Low confidence.

Outlook...

Friday through Friday night...VFR. Slight chance of a shower.

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 Memorial Day...Sub-VFR conditions probable
with a chance of showers and thunderstorms.

&&

.MARINE...
The conditions are expected to remain below Small Craft Advisory
criteria through Thursday night, however a few gusty thunderstorms
will be possible especially Thursday afternoon and evening.

Outlook...

Friday through Monday...No marine headlines expected. Winds will
periodically gust up to 15-20 kt with seas around 2-4 feet. A chance
for showers and thunderstorms is expected on Saturday night and for
Sunday night into Monday.

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...Gorse/MJL
SHORT TERM...Deal/DeSilva
LONG TERM...Deal/DeSilva
AVIATION...Deal/DeSilva/Gorse/MJL
MARINE...Deal/DeSilva/MJL
TIDES/COASTAL FLOODING...PHI