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906
FXUS61 KPHI 281347
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
947 AM EDT Tue May 28 2024

.SYNOPSIS...
Initial cold front pushes through the region and offshore this
morning, followed by a secondary front later this afternoon. Another
low pressure system affects the region Wednesday into Thursday
before high pressure returns Friday and holds strong into the
weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
Mostly sunny skies this morning, then clouds increase as another
front will cross the region this afternoon while an upper
trough approaches from the west.

While temperatures will not be much cooler behind the front, a
much drier air mass will overspread the region with surface dew
points falling into the 50s. These dew points will also be
lowered due to efficient afternoon mixing up to 850 mb and west
winds increasing to 15 to 20 mph with 25 mph gusts. While highs
will be similar, if not a couple of degrees warmer than Monday,
generally in the upper 70s to low 80s, it will feel much more
comfortable.

Aided by some strong shortwave energy, isolated showers and
perhaps a thunderstorm are possible for the southern Poconos,
northern New Jersey, and the Lehigh Valley this afternoon with
the passage of that secondary front. The severe threat will be
minimal, as SB CAPE values will generally be up around 500 J/kg,
although 0-6 km Bulk Shear values will be 45 to 55 kt.

Will also add a slight chance for showers and thunderstorms for
portions of Delmarva late this afternoon/early this evening as
weak shortwave energy passes through the Mid-Atlantic as well.

Any showers and thunderstorms will end fairly quickly after
sunset with loss of diurnal heating. Lows tonight will be in the
50s to low 60s.
-- End Changed Discussion --

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
The short term forecast will be relatively active with chances for
showers and thunderstorms through much of the period. The advection
of a vorticity max through the upper-level trough lying across the
eastern United States will be the impetus for the development of
another shortwave that moves through the region Wednesday into
Thursday.

Latest guidance depicts the shortwave beginning to push into the
region during the afternoon on Wednesday, allowing it to take
maximum advantage of daytime heating. However, thanks to the fronts
passing through the region on Tuesday, low-level moisture will be on
the lower side (surface dewpoints in the mid 50s at best). In
combination with high temperatures in the mid-upper 70s, only modest
surface based CAPE will result (500-750 J/kg). Model soundings
indicate that shear will also be on the lower side (30-35 kts) and
unidirectional. Putting all the pieces together, a few stronger
thunderstorms will be possible but severe potential is low.

The shortwave will continue passing through the region Wednesday
night and looks to push offshore early Thursday. Lingering showers
and storms will be possible Thursday into Thursday night. However,
instability will continue to be a limiting factor, even more so
during this period, as behind the wave, dewpoints look to drop into
the upper 40s/low 50s with highs on Thursday in the low-mid 70s.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
The long term period looks to feature a sustained period of dry
weather with temperatures gradually warming. This trend will be due
to strong high pressure which begins to build into the region on
Friday before becoming centered over the region during the weekend.
The high will be supported by an upper-level ridge, though by late
in the weekend, the ridge may begin to flatten out with more zonal
flow or a weak upper-level trough returning.

In terms of sensible weather, conditions should be dry through at
least Saturday night. The dry weather looks likely to continue into
Sunday and Monday as well unless the aforementioned changing upper-
level pattern suppresses the surface high enough to allow a weak
surface low to pass through. Only slight chance PoPs (15-25%) are in
the forecast for now though. Temperatures will begin slightly below
normal in the mid 70s on Friday before warming to near normal (upper
70s-low 80s) over the weekend, and potentially above normal by
Monday.

&&

.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas...

Today...VFR. Cannot rule out a passing SHRA or TSRA at
KRDG/KABE this afternoon. W-NW winds 10 to 15 kt with 20 to 25
kt gusts this afternoon. High confidence overall, though
confidence is too low to warrant mentioning SHRA/TSRA at
KRDG/KABE TAF.

Tonight...VFR. W winds 5 to 10 kt. High confidence.

Outlook...

Wednesday through Thursday...Sub-VFR conditions possible with
chances (40-60% Wednesday/30-50% Thursday) for showers and
thunderstorms.

Thursday night through Saturday...VFR with no significant
weather.

&&

.MARINE...
Sub-Small Craft Advisory conditions today through tonight. SW
winds 10 to 15 kt, becoming W late this morning. Gusts 20 to 22
kt this afternoon. Winds 5 to 10 kt tonight. Seas around 3 feet
on the ocean and 1 to 2 feet on Delaware Bay.

Outlook...

Wednesday through Saturday...Sub-SCA conditions expected throughout
the period. Showers and thunderstorms possible (30-50%) Wednesday-
Thursday.

Rip Currents...

SW winds this morning will become W and increase to 15 to 20
mph with gusts up to 25 mph. Although the flow will be offshore,
gusty winds will result in a MODERATE risk for the development
of dangerous rip currents at NJ beaches and a LOW risk at DE
beaches.

Winds will be much lighter on Wednesday. As a result, there is
a LOW risk for the development of dangerous rip currents at NJ
and DE beaches.

As always, rip currents can still develop, and often occur in
the vicinities of jetties and piers. Utilize any guarded beaches
this holiday weekend if venturing out into the water.

&&

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

&&

$$

SYNOPSIS...AKL
NEAR TERM...MJL/MPS
SHORT TERM...AKL
LONG TERM...AKL
AVIATION...AKL/MPS
MARINE...AKL/MPS