901
FXUS61 KPHI 292351
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
751 PM EDT Wed May 29 2024

.SYNOPSIS...
A weak cold front passes offshore tonight and may stall some
thereafter. High pressure builds in Thursday and holds dominate
influence over the region into Sunday. Unsettled conditions
could return by late Sunday and continue into the middle of next
week.

&&

.NEAR TERM /THROUGH THURSDAY/...
As of 6:20PM...Latest radar imagery shows a wide swath of
showers with embedded thunderstorms in SE Pennsylvania with
more in the way of showers across the Poconos and Delmarva. This
area of precip will continue to pivot northeast with time as
the surface low transverses across Pennsylvania this evening.
Have seen a few organized areas of convection off to the south
earlier, but this has since waned. Mesoanalysis shows SBCAPE
values reaching around 500 J/kg across the Delmarva and E PA
with hi-res guidance suggesting values to reach into the 1000
J/kg range in some locations. Deep layer 0-6km shear values will
be best across the southern Delmarva, but the shear profiles
will be largely unidirectional or incoherent and not favorable
for severe development.

In terms of flooding concerns...rainfall forecast amounts have
increased slightly overall with areas across northeast PA and
northern NJ around 0.50-1.00 inches with locally higher amounts
possible. While areas south of I-78 will see storms progress a bit
more with embedded downpours, areas along and north of the
interstate could see some steady moderate rainfall train across the
region beginning this evening and into tonight with some heavier
pockets at times. That said, some localized flooding may be possible
later this evening and into the late night hours as this storm
slowly shifts offshore.

Overnight lows will be in the mid 50s. Skies will be mostly cloudy
and begin to clear towards sunrise early Thursday morning. Some
showers may linger across eastern NJ prior to sunrise.

Thursday looks to stay mostly dry, though a few isolated showers and
possibly a thunderstorm could develop in the afternoon as our mid
level trough remains over head. A weak shortwave will pivot around
the main trough and provide some weak and broad ascent across our
forecast area. While the best forcing will be south of the region,
we can`t rule out a few isolated showers across NJ and parts of the
Delmarva. That said, dew points at the surface will be in the upper
40s to low 50s and some showers may not reach the ground. Otherwise,
mostly sunny with highs around the low to mid 70s.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
The region will feel the influence of surface high pressure
throughout the duration of the short term. Surface high pressure
centered to our west Thursday night will gradually move eastward
with time. This surface high pressure will look to be centered over
the region for Saturday.

With surface high pressure in control of the region, expect a nice
and quiet short term with pleasant conditions. Some lingering
shortwave energy could persist into the first half of Thursday
night; a quick and isolated pop-up shower cannot be ruled out
entirely, but overall things will be quiet for the period. Friday
and Saturday will be beautiful sunny and dry days with surface high
pressure in control. We are looking at highs in the 70s Friday with
dewpoints in the 40s. For Saturday, we are looking at highs near 80F
with dewpoints mainly in the 40s. Both days will feel very
comfortable; being outdoors will be enjoyable.

Mainly clear skies will be present Thursday night and Friday night
with light winds in the forecast. Decent radiational cooling will
likely occur both nights. Overnight lows in the low to mid 50s can
be anticipated both nights.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Ensembles and deterministic models suggests a more zonal upper-level
pattern will take hold over the CONUS for long term. At the surface
level, guidance suggests surface high pressure will continue to hold
influence over the region Saturday night into Sunday while
continuing to move eastwards/southeastwards and offshore. As the
high shifts further offshore of the eastern CONUS with time Sunday
into Tuesday, some weak low pressure, associated fronts, and
shortwave energy could be invited to influence the region later
Sunday into next week. Overall, things could generally become
unsettled again Sunday afternoon onwards.

Not much confidence in details of the long term forecast today with
the forecast zonal upper-level pattern and its slow evolution.
Expect unsettled conditions Sunday afternoon onwards with chances
for showers and thunderstorms in the afternoons/evenings.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas...

Tonight...VFR expected, with some scattered low clouds at times.
Removed the mention of thunder at all TAF sites as the primary
round of thunderstorms have moved away from the area. Expect
mostly periods of light rain and scattered showers through 06Z.
After 06Z, rain should taper off to more isolated showers.
Variable winds initially, becoming W-NW winds around 5-10 kt.
Low confidence overall.

Thursday...VFR expected. Slight chance of a shower for I-95
terminals during the afternoon, but confidence is not high so
left out of the TAF. NW-N winds around 10 kt. Moderate
confidence.

Outlook...

Thursday night through Saturday night...VFR. High confidence.

Sunday...Mainly VFR. Sub-VFR cigs could develop for some sites by
the afternoon. Moderate confidence.

Monday...Mainly VFR, though some sub-VFR cigs could linger. Moderate
confidence.

&&

.MARINE...
Sub-SCA conditions through Thursday. Southerly winds this
evening around 10kt will shift W-NW overnight. Showers and a
few thunderstorms possible with a surface low moving east
tonight and out to sea early Thursday. Winds shift N-NE around
10 kt on Thursday. Seas will linger around 2-3 feet.

Outlook...

Thursday night through Monday...No marine headlines anticipated.

Rip Currents...

For Thursday, northwest winds around 10 mph will veer northeast
in the afternoon. Breaking waves will be 2 to 3 feet. With the
lighter winds and shorter period swells, there will continue to
be a LOW risk for the development of dangerous rip currents
along the New Jersey and Delaware beaches.

Friday will be very similar to Thursday. North winds around 10
mph will become northeast later in the day. Breaking waves will
be about 2 feet. This will result in a LOW risk for the
development of dangerous rip currents along 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...Wunderlin
NEAR TERM...DeSilva/MJL
SHORT TERM...Wunderlin
LONG TERM...Wunderlin
AVIATION...DeSilva/MJL/Wunderlin
MARINE...MJL/Wunderlin