973
FXUS61 KPHI 230548
AFDPHI

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

.SYNOPSIS...
High pressure to the southeast of our region will move further
out to sea overnight. A cold front will approach the area on Thursday
before crossing through the area on Thursday night. 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 TODAY/...
A closed low centered just north of the Midwest and upper Great
Lakes region will gradually shift eastward through Thursday night.
Surface low pressure will also travel with it, and an associated
cold front will cross our area Thursday night. Some convection is
expected ahead of this cold front and with with a surface trough.

Showers and tstms associated with the lee-side trough and convective
MCV that developed earlier today have weakened somewhat as the
move mostly to the north of our area. Widely scattered showers
are still possible overnight, so we`ll keep some slight chc/chc
pops in the grids.

Recent guidance continues to hint that a convectively induced
shortwave (or MCV) could result in additional convection late
tonight and towards dawn Thu. The placement of this is less certain,
however there is some potential for a round of some showers and thunderstorms
to start Thursday morning. This activity if it were to be realized
should be sub- severe with some decrease in the instability and
more stable boundary layer. The extent and timing of morning
convection will have an influence on the rest of Thursday as the
cold front arrives. An overall trend in the guidance is for the
modestly increased southwesterly mid level flow to occur in the
morning with this flow weakening through the afternoon. High
level winds remain stronger, however it is the lower winds that
are forecast to be weaker. The amount of instability that is
forecast is enough to sustain thunderstorm development through
the afternoon, however the main forcing is well removed from our
area given the main trough aloft is well to our north. If the
morning convection does not occur or it is much more isolated,
then the model forecast soundings show a low-level inverted-V
profile developing as more boundary layer heating will occur. At
least some showers and thunderstorms are expected throughout
the day, and there remains the potential for at least isolated
severe thunderstorms. Locally damaging winds is the main hazard,
especially if storms are able to become more organized such as
in a cluster or a line segment. Given the weaker wind field
overall that is forecast, the severe thunderstorm risk remains
at Marginal or a level 1 out of 5.

Any showers and thunderstorms are expected to be weakening and/or
moving offshore Thursday night as the cold front shifts to our east.
Some drier air then arrives later Thursday night in the wake of the
cold front, however prior to that patchy fog cannot be ruled out
especially where rain occurs and if the cloud cover clears
enough.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
The cold front will continue to 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.
Still will mention a slight chance of a shower across the Delmarva
in the afternoon, but this is becoming increasingly less likely.
Skies will clear behind the front as dewpoints fall back into the
50s. Overall, Friday is shaping up to be a pretty pleasant day to
kick off the holiday weekend with temps in the low to mid 80s, with
shore points in the 70s.

Quiet weather will continue into Friday night with clear skies and
light winds. We should be able to radiate pretty well initially,
however clouds will increase from south to north later in the night.
This will limit the amount of cooling late, resulting in warmer
than normal lows ranging in the upper 50s to mid 60s.

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. Basis current
trends amongst forecast guidance, it does appear the first half of
Saturday will remain 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. Another
warm front will likely pass over the area on Monday with a
potentially stronger cold front crossing the area Monday night into
Tuesday. Will have to watch this closely in the coming days as some
of the analog based and machine learning guidance suggest severe
weather may be on the table. But this is quite a few days away.
After the cold front passes, shower chances should continue through
the middle of next week thanks to several waves/impulses aloft. For
now, will carry a chance of showers into the middle of next week.

In terms of temperatures for the long term period, Sunday appears to
be a few degrees above average, Monday and Tuesday close to average,
with Wednesday looking below average.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas...

Rest of tonight (through 12Z)...VFR for much of the night. Some
sub- VFR conditions with some showers or thunderstorms possible
towards dawn. Light HZ/BR possible for the NW areas too. Light
S/SW winds. Low/medium confid.

Thursday...Some showers and thunderstorms around resulting in a time
of sub-VFR conditions. Southwest winds 5-10 knots, becoming west to
west-northwest 5 knots or less later at night. Low confidence in
timing and coverage of showers/storms.

Thursday night...Lingering scattered showers and thunderstorms
could result in brief sub-VFR conditions early in the evening,
but coverage should diminish later into the nighttime hours.
VFR conditions should largely return overnight, though ACY looks
to see lower visibilities and cigs as showers will linger
around here a bit longer. That said, some patchy fog cannot be
ruled out, especially across locations that see rainfall earlier
in the day. Low confidence.

Outlook...

Friday through Friday night...Sub-VFR possible early, becoming 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 Monday...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 on Thursday along with
breaking waves around 2 feet. There is a LOW risk for the
development of dangerous and life threatening rip currents at NJ
and DE beaches for Thursday. However, showers and thunderstorms
are likely, and may be capable of strong wind gusts and hail.

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 and life threatening rip
currents at NJ and DE beaches for Friday. 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
on Thursday, 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...DeSilva/Gorse
NEAR TERM...Gorse
SHORT TERM...DeSilva
LONG TERM...DeSilva
AVIATION...DeSilva/Gorse/MJL
MARINE...DeSilva/Gorse/MPS
TIDES/COASTAL FLOODING...