789
FXUS61 KPHI 210753
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
353 AM EDT Tue May 21 2024

.SYNOPSIS...
High pressure shifts slightly to the south today then out to sea
Wednesday. A cold front will approach the area Wednesday night,
before slowly moving across the area on Thursday, then stalls to our
south through the weekend. Several waves of low pressure and may
develop and move along this boundary over the weekend into early
next week, bringing unsettled weather to the area.

&&

.NEAR TERM /THROUGH TONIGHT/...
Areas of fog and low stratus are beginning to overspread southern
NJ, coastal DE, and southeast PA early this morning. Expecting
coverage to gradually increase over the next several hours until
daybreak arrives and begins to mix out any fog or low stratus.

Fog and/or low stratus this morning will dissipate by mid-morning
and give way to clear skies in the afternoon with some fair-weather
cumulus. Another dry and quiet weather day is expected. High temps
should be a bit warmer than those of today, rising into the upper
70s to mid 80s. Temps will be noticeably cooler along/near the shore
thanks to light surface winds allowing an afternoon sea breeze
circulation to develop.

Another tranquil night with mostly clear skies and calm winds. Light
SSWrly flow should inhibit much organized fog outside the immediate
coast, but some patchy fog will be possible. Lows in the mid 50s to
around 60.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
High pressure will move farther away from the area and out to sea on
Wednesday, losing its effect on the weather across the area. Dry
conditions are expected early in the day on Wednesday, but showers
will be possible by the end of the day as a mid/upper level
disturbance moves in to the area. Showers and thunderstorms become
more likely on Wednesday night as a pre-frontal trough may develop
across the area while the aforementioned mid/upper level disturbance
slowly moves across the area.  Showers and thunderstorms become even
more likely on Thursday and into Thursday evening as the cold front
moves across the area. There is some instability forecast across the
area, with CAPE values potentially reaching 1000-2000 J/kg, with
some shear across the area with 30-40 knots. So there will be the
potential for some strong to severe storms to develop across the
area.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
The cold front is expected to stall to the south Friday and into the
weekend, before possibly lifting north of the area on Monday.
leading to possible unsettled weather. A couple of waves of low
pressure are expected to move across the area as the front stalls
near the area Friday and Saturday. This will lead to a period of
possible unsettled weather with a chance of showers and
thunderstorms. As these disturbances move to the east Sunday, it is
possible that the shower activity will diminish on Sunday. However,
another area of low pressure could begin to move into the area
Sunday night into Monday, bringing addition unsettled conditions to
the area.

&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas...

Early this morning (through 12Z)...VFR to start for most, but
marine fog is forecast to advect inland later this morning,
leading to areas of mist and fog. A few sites have already seen
moments of IFR or lower at times during the overnight period.
IFR CIGs/VSBYs become more prevalent at KACY/KMIV after 08-10Z.
MVFR CIGs/VSBY will become more prevailing across the I-95
terminals with moments of IFR possible. KABE/KRDG will likely
remain in VFR/MVFR. Moderate confidence overall, but lower with
respect to timing of CIGs/VSBY reductions.

Tuesday...Any IFR/MVFR CIGs should rise to VFR by 14-16Z at all
terminals. Mostly clear skies during the afternoon. South-
southwest winds around 5-10 kt. High confidence.

Outlook...

Wednesday...Generally VFR except lower conditions possible around
daybreak.

Wednesday night-Thursday night...Sub-VFR conditions possible with a
chance of showers and thunderstorms.

Friday...VFR conditions expected with a slight chance of showers
during the day.

Friday night-Saturday...Chance of showers with periods of lower
conditions possible.

&&

.MARINE...
Areas of fog over the marine zones this morning, including the
Atlantic Coastal waters and Delaware Bay. Otherwise, marine
conditions are expected to remain below small craft advisory
criteria. Light and variable winds this morning will become more S
to SSW this afternoon into the overnight period around 10-15 kt with
occasional gusts up to 20 kt. Seas 2-3 feet.

Outlook...

Wednesday-Saturday...Conditions expected to remain below Small Craft
Advisory levels.  However, winds will gust around 20 knots at times
and seas could rise to 4 feet at times.

Rip Currents...

Winds become S from 5 to 15 mph on Tuesday. Winds in northern
NJ will be closer to 10 to 15 mph, and winds at coastal DE will
be a bit more offshore. For beaches in Monmouth, Ocean,
southeast Burlington counties, as well as Delaware beaches,
there is a MODERATE risk for the development of dangerous and
life threatening rip currents. For southern NJ, winds will be a
bit lighter, generally 5 to 10 mph. As a result, there is a LOW
risk for the development of dangerous and life threatening rip
currents for beaches in Atlantic and Cape May counties.

There will be a Full Moon on May 23. S winds will range from 10
to 15 mph with gusts up to 20 mph. As a result, there is a
MODERATE risk for the development of dangerous and lift
threatening rip currents at NJ and DE beaches on Wednesday.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Dense Fog Advisory until 8 AM EDT this morning for ANZ430-431-
     454-455.

&&

$$

SYNOPSIS...Robertson
NEAR TERM...MJL
SHORT TERM...Robertson
LONG TERM...Robertson
AVIATION...MJL/Robertson
MARINE...MJL/Robertson