623
FXUS61 KPHI 291035
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
635 AM EDT Wed May 29 2024

.SYNOPSIS...
Surface low pressure system approaches the region today, bringing
some showers and thunderstorms with it, before passing offshore late
tonight. High pressure then returns and holds strong into the
weekend. Next opportunity for showers and storms could be as early
as Sunday but the associated low may not arrive until Monday or
Tuesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
Will adjust hourly grids based on latest surface obs.
Otherwise, no significant changes will be made to the previous
forecast.

Weak surface low pressure lies over the Ohio Valley, while the
base of an H5 trough is just behind it over the Great Lakes. Low
pressure will intensify as it and the upper trough track east.
The low passes over New Jersey tonight before tracking east and
departing by daybreak Thursday.

In terms of sensible weather, conditions start out dry this
morning. Clouds increase over the area as low pressure
approaches from the west. Showers will become likely over the
northern half of the forecast area late this afternoon/early
this evening, and there is the chance for thunderstorms. SB CAPE
values will be up around 500 J/kg and although 0-6 km Bulk
Shear values will be 30 to 40 kt over the southern half of the
forecast area, those values will be 20 to 30 kt over the
northern half of the forecast area, which is where the surface
low will track. Not expecting severe weather, but a few
lightning strikes, brief downpours and wind gusts to 30 mph or
so will be possible.

With low pressure near Long Island late tonight, some wrap
around showers will continue over northern New Jersey and into
portions of the southern Poconos and Lehigh Valley into the late
night hours.

Highs will be right around normal levels for this time of the
year, topping off in the mid to upper 70s. Lows tonight will
mainly be in the 50s.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
The only potential for rain during the short term forecast period
looks to be right at the start during the daytime hours on Thursday.
Lingering surface low pressure to our northeast may continue to
throw a few showers or a thunderstorm back towards our region as the
axis of the upper-level trough makes its slow march eastward.
Coverage looks to be pretty isolated though as continued drying of
the atmosphere will drop surface dew points into the upper 40s/low
50s. CAPE values will only be a few hundred joules/kilogram at best
as a result. High temperatures on Thursday will be in the low-mid
70s which will make for a very comfortable, if not slightly cool for
late May, day. The upper-level trough axis will finally push through
the region Thursday night and temperatures will fall into the 50s
(upper 40s at higher elevations) with mostly clear skies.

Surface high pressure will be entrenching itself as we head into
daytime Friday and the northerly flow will make for another
relatively cool last day of May. Temperatures look to be very
similar to Thursday with highs in the low-mid 70s and lows mainly in
the 50s.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
Surface high pressure will continue to be the dominate feature
across the region to start the long term forecast period as an
amplified upper-level ridge continues to work its way eastward.
Model guidance forecast suites do begin to diverge by the end of
the weekend with the GFS/ECMWF showing the ridge passing offshore
Sunday-Sunday night followed by a weak upper-level trough while the
GEM depicts the ridge holding a bit stronger and delaying the
arrival of the trough.

In terms of sensible weather, conditions should be dry through at
least Saturday night. The dry weather looks likely to continue into
Sunday and possibly Monday as well if the ridge is able to hold
strong enough to suppress the oncoming trough. By Tuesday though, the
pattern looks to certainly be more active with high pressure pushed
out of the region. Only slight chance PoPs (15-25%) are in the
forecast for the most western portions of the region. Slight chance
PoPs are spread through more of the region for Sunday night through
Monday night and PoPs increase to 20-30% on Tuesday. High
temperatures look to be near normal (upper 70s-low 80s) through
Monday, and potentially above normal by Tuesday.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas...

Today...VFR conditions overall. SHRA will become likely this
afternoon and into this evening, but confidence is low that sub-
VFR conditions will occur in any SHRA at any given time. For
now, will mention -SHRA in the TAF, but will keep conditions
VFR. A few TSRA possible as well, but confidence is even lower
that a given TSRA will pass over a given terminal. For that
reason, will not mention TSRA in the TAF. W-NW winds 5-10 kt.
Low confidence on timing of potential restrictions.

Tonight...Once again, VFR overall, but potential for sub-VFR in
any SHRA or even TSRA passing over a given terminal. Will leave
out of TAF for now due to low confidence. Also the potential
for sub- VFR CIGs after 06Z at any terminal where it rains. Will
not include in the TAF this time. N-NW winds around 5 kt. Low
confidence.

Outlook...

Thursday...Mainly VFR expected. Sub-VFR conditions possible though
with a slight chance (15-25%) for showers or a thunderstorm.

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

&&

.MARINE...
Sub-Small Craft Advisory conditions today and tonight. W-NW winds 5
to 10 kt this morning will turn S around 10 kt by this afternoon. As
low pressure passes north of the waters late tonight, winds turn NW
at 5 o 10 kt by early Thursday morning. Seas 2 to 3 feet.

Outlook...

Thursday through Sunday...Sub-SCA conditions expected throughout the
period.

Rip Currents...

West to northwest winds at 5 to 10 mph this morning will become
south by this afternoon. Breaking waves will average 1 to 2 feet.
There is a LOW risk for the development of dangerous rip currents
for the New Jersey and Delaware beaches.

For Thursday, west to northwest winds 5 to 10 mph will turn north in
the afternoon. Breaking waves will once again average 1 to 2 feet.
Therefore, there will continue to be a LOW risk for the development
of dangerous rip currents for the New Jersey and Delaware beaches.

For specific beach forecasts, visit weather.gov/beach/phi

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

&&

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

&&

$$

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