800
FXUS61 KPHI 291936
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
336 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/...
Latest radar imagery shows scattered showers and isolated
thunderstorms beginning to enter the forecast area. Expecting to see
coverage increase through the afternoon and into the evening as a
weak surface low shifts across the state of PA.

In terms of the severe potential...mesoanalysis shows SBCAPE values
reaching around 500 J/kg across the Delmarva and eastern PA at the
moment with hi res guidance suggesting values to reach into the 1000
J/kg range in some locations, which could help fuel some gusty winds
and heavier downpours. 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 /20Z WEDNESDAY THROUGH MONDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas...

Rest of today (through 00Z)...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. Still will
place a VCTS in the forecast, however. 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. N-NW winds around 5
kt. Low confidence.

Thursday...Mainly VFR expected. Sub-VFR conditions possible in the
afternoon for I-95 terminals and east with a slight chance (15-25%)
for a quick shower or a thunderstorm. NNW winds 5-10 kts. 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.  Light southerly winds this
afternoon around 10kts will shift W-WNW 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 kts during the
day Thursday. Seas will linger around 2-3 feet.

Outlook...

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

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...Wunderlin
NEAR TERM...MJL
SHORT TERM...Wunderlin
LONG TERM...Wunderlin
AVIATION...MJL/Wunderlin
MARINE...MJL/Wunderlin