-- Discussion containing changed information from previous version are highlighted. --
490
FXUS61 KPHI 030142
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
942 PM EDT Sun Jun 2 2024

.SYNOPSIS...
A weak system approaches for tonight into Monday. High pressure
moves in on Monday Night remaining in control through early
Wednesday. An upper level low then will move into the Great
Lakes, keeping things unsettled into next weekend.

&&

.NEAR TERM /THROUGH MONDAY/...
A weakening shortwave approaches into tonight, rotating around
the backside of an upper level low over the north Atlantic. This
will bring some scattered showers and perhaps a garden-variety
rumble of thunder, but nothing to write home about. So far,
light radar returns have produced sprinkles at best in some
isolated areas as the air below the cloud layer remains quite
dry. As the column saturates more into tonight, more of this
activity should begin to reach the ground. Chances for showers
increase to around 30-50% for most of the area after midnight,
except a bit higher (around 60 percent) over portions of
Delmarva and far southern NJ, where the best chance for
thunderstorms overnight are also located. Expect lows mostly in
the mid 60s.

A few lingering showers and an isolated thunderstorm across
southern NJ and southern Delmarva will clear out shortly after
daybreak Monday morning with a dry period from mid morning
through early afternoon. Another shortwave will pivot around an
offshore upper low across the region. Any cloud cover lingering
early in the morning will scatter out through the remaining
morning hours and into the early afternoon for much of the
region, allowing for modest destabilization ahead of this
shortwave.

Hi res guidance shows MUCAPE values around the 1000 J/kg range
by the afternoon, and perhaps more notably DCAPE increasing to
near 1000 J/kg as well. With dewpoints in the 60s, the
ingredients are there for a few scattered showers and
thunderstorms to develop by mid afternoon. With the dry mid-
level air, convective initiation (CI) will likely fail early in
the afternoon. However, modest low-level moisture and continued
CI attempts in persistent areas should eventually support some
isolated to scattered convection by mid to late afternoon (3 PM
onward). There will be some surface confluence across the
coastal plain, which should be a focusing mechanism for CI, and
will likely result in the greatest coverage/strength of
convection in this area as well. The severe potential with
these storms, however, will remain on the low end with deep
layer shear being rather lackluster in the afternoon around 20
kts at best. Nevertheless, the higher DCAPE and mid-level dry
air could support some downbursts with any more robust cells
that are able to develop. With PWAT values in the 1-1.5 inch
range, a few good downpours may be possible with a stronger
storm, but any flooding concerns will be very localized and
brief. High temperatures are forecast to reach the mid 80s in
most areas with scattered cumulus clouds following any lingering
morning clouds.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
We dry out Monday Night through Tuesday as high pressure nudges
in from the north. With the high positioned just offshore, an
onshore flow will develop which will result in temperatures in
the low to mid 70s near the coast, with upper 70s/low 80s
elsewhere. Tuesday Night should be dry, though the high begins
to retreat offshore. Clouds will increase through the night as
the next system approaches. Lows will drop into the upper
50s/low 60s.

A shortwave approaches for Wednesday ahead of a large upper
level low swinging down from Canada. This will result in some
showers and isolated thunderstorms moving through, primarily in
the afternoon and evening. Looking at some of the ensembles and
deterministic guidance, there really isn`t a strong signal for
any severe weather as instability looks meager. The same goes
for any shear. Thinking the day will be mainly cloudy, with some
periods of rain with some rumbles of thunder mixed in.
Temperatures will be in the upper 70s/low 80s.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Long term period will be marked by unsettled weather due to a
closed low moving into the Great Lakes region and meandering
through the weekend. This will result in numerous shortwaves
rounding the base of the closed low and moving towards our
region with several associated frontal systems passing through
and an unsettled end of the week and weekend.

The strongest shortwave looks to approach on Thursday, with an
associated cold front moving through sometime late in the week.
Both the 00z and 12z guidance continues to speed up the timing
of the initial from to come through more towards Thursday
morning. This would limit the severe potential, compared to if
the front come through later in the day. Overall, the signal for
severe weather isn`t overly strong given the instability
currently forecast does not look that impressive. Out ahead of
the front, widespread showers and embedded thunderstorms look to
develop. Wednesday Night/Thursday time frame has the highest
rain chances (around 60-70%). Outside of that window, generally
expecting scattered showers and isolated thunderstorms, mainly
in the afternoon/early evening timeframe of Friday through
Sunday. PoPs for those days are only around 20-40%, so it is
fair to call it unsettled but not a total washout as the upper
level hangs around.

Temperatures will hover near or perhaps a touch below normal
for early June for the long term period.

&&

.AVIATION /02Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Tonight...Clouds lowering, but remaining VFR through at least
03-06Z. Some brief restrictions possible overnight as some
showers and embedded thunder move in along with lower cigs and
the potential for some patchy fog as well. ILG/MIV/ACY have the
greatest chance at brief sub-VFR and thunder overnight, so opted
to include a TEMP ground for TSRA there. Winds generally SW
around 5 knots or less. Moderate confidence.

Monday...Prevailing VFR conditions with scattered clouds.
Chance (30%-50%) of a shower/tstm after 18Z. Brief period of
sub- VFR conditions possible with a stronger storm. Moderate
confidence.

Outlook...

Monday Night...Primarily VFR. Some patchy fog possible (20-30%)
at KACY/KMIV.

Tuesday through Tuesday Night...VFR. No significant weather.

Wednesday...Primarily VFR though showers/isolated thunderstorms
arriving late in the day could bring some restrictions.

Wednesday Night through Thursday...Restrictions likely (70-80%)
with widespread showers and scattered thunderstorms moving
through.

Thursday Night through Friday...Conditions should lift back to
VFR at some point but lingering showers/isolated thunderstorms
could result in further restrictions.
-- End Changed Discussion --

&&

.MARINE...
No marine headlines anticipated through Monday. S to SSW winds
10-15 kts may briefly gust up to 20 kts this evening before
diminishing to 5-10 kts by Monday morning where they will linger
through the rest of the day. Seas 2-3 feet. A few showers and
thunderstorms possible tonight and Monday afternoon.

Outlook...

Monday Night through Wednesday...No marine headlines expected.
Fair weather.

Wednesday Night through Thursday...SCA conditions possible
(30-40% chance) with gusts nearing 25 kt. Periods of showers and
thunderstorms likely.

Rip Currents...

A LOW risk for the development of rip currents is in place for
Monday and Tuesday. While winds turn partially onshore for
Monday and then fully onshore for Tuesday, wind speeds will be
around 10 MPH, with continuing 1 to 2 foot waves and short to
medium period which keeps the overall risk for rip current
development low.

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

Rip currents occur often 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...Hoeflich
NEAR TERM...MJL/Staarmann
SHORT TERM...Hoeflich
LONG TERM...Hoeflich
AVIATION...Hoeflich/MJL/Staarmann
MARINE...AKL/Hoeflich/MJL