-- Discussion containing changed information from previous version are highlighted. --
978
FXUS61 KPHI 130608
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
208 AM EDT Thu Jun 13 2024

.SYNOPSIS...
Weak surface high pressure remains in control through Thursday
night. A cold front crosses through the region Friday afternoon
into Friday night. High pressure builds in thereafter and holds
influence over the region into the beginning of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Weak surface high pressure is currently centered over the
region. This weak surface high pressure will move eastward with
time, looking to be offshore come this afternoon/evening. The
region will still feel the influence of some weak surface high
pressure tonight, though a cold front from the northwest will
approach. Overall, the near term will remain fairly quiet.

With weak surface high pressure centered overhead early this
morning, mainly clear skies and light and variable winds are in
the forecast. Some radiational cooling will continue to take
hold. Some very light patchy ground fog may occur during the
early morning hours for some areas.

We will see some nice warm air advection today with
S/SW surface flow. Mainly partly cloudy skies are in the
forecast with highs of the mid 80s anticipated for most areas.
There is some indication of some upper-level shortwave energy
and cyclonic vorticity being in place this afternoon/evening.
While the forecast continues to have no PoP with this update, a
slight chance of some isolated pop-up showers should not be
ruled out entirely.

Mainly quiet conditions continue into tonight; overnight lows in
the 60s anticipated.

&&

.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
Dry conditions continue through Thursday night before a sharp
cold front approaches the region Friday. Timing of the cold
front`s passage will largely be the driver in what happens
across the region. The 12z suite of guidance is still indicating
that the highest chance of timing would bring the front through
late afternoon/early evening.

That timing would start to show support for organized showers
and thunderstorms with the potential for severe weather. Both
the GEM and GFS show ample instability approaching 18-21z with
30-35kts of 0-6km shear and sufficient LI`s. The highest shear
totals are currently being forecast to occur slightly to the
north however the soundings currently suggest from roughly
Trenton north that organized severe weather has at least a 15%
chance. In addition, with the surge of PWAT increasing between
18z-00z close to 1.75" any storm could be capable of producing
heavy rainfall. While the soil moistures are relatively dry over
the past few weeks, poor drainage and impervious surfaces could
be subject to flooding.

Concerning temperatures, warm air advection should be in place
across the region Thursday night and continues through Friday
until the cold front. This leads to overnight lows Thursday in
the upper 60s to low 70s, highs before the front Friday warming
into the low 90s, and then down into the upper 50s to low 60s
Friday night.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Behind the cold front the synoptic pattern sets up with a
building ridge through the weekend. Heights will quickly rise
across the Mid Atlantic with a mid level ridge dominating
through at least the early portion of next week. While the
surface high will start to push offshore, all that does is setup
southerly return flow leading to warm temperatures being
advected north. While ensembles suggest anomalous heights around
588-592 dam over the region, the EC EFI only rates this as
slightly above normal for Monday and Tuesday. None the less,
heat will be a concern with 925mb temps likely to be in excess
of 21-22C. This translates into 60-70% chance of seeing highs
above 95F either Monday or Tuesday and little in the way of
recovery overnight. Given that guidance has been fairly
consistent with the building high pressure and warming temps,
its certainly not too early to start thinking about cooling
options for the upcoming week. While there are some pulses of
PVA tracking through the region Monday night and Tuesday
evening, the overall chance for showers is fairly capped
(10-15%) due to needing a trigger. At this point, a large number
of ensembles show the ridge starting to deamplify but still
holding on till late in the week. This would allow for some
weakening in max temps during the day but not much.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
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The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

Before 12Z...VFR/SKC. Winds mainly light and variable. Some
light patchy ground fog may develop at a few sites (e.g.,
KRDG/KMIV/KACY) but sub-VFR visibility`s are not expected. High
confidence.

Today...VFR. SSW winds around 5 kts in the morning, then 10-15
kts with occasional gusts up to 20 kts in the afternoon. High
confidence.

Thursday night...VFR. SSW winds 5-10 kts. High confidence.

Outlook...

Friday through Friday night...Sub-VFR conditions possible with
thunderstorms during the afternoon/evening.

Saturday through Sunday...VFR with mostly clear skies. No
significant weather expected.
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&&

.MARINE...
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Thursday/Thursday night...South winds increase up to 13-18 kts
with gusts up to 23 kts this afternoon/evening. Seas around 3-4
feet. Marine headlines are largely not anticipated. However,
brief SCA conditions are possible for ANZ450/ANZ451 due to gusty
winds. With gusts currently forecast to be so briefly
borderline/marginal, opting to not issue any headlines for now.
Otherwise, fair weather.

Outlook...

Friday through Friday night...SCA conditions possible Friday
due to winds gusting up to 20-25 kts and seas of 3-5 feet. A
chance of thunderstorms later Friday and Friday night.

Saturday through Sunday...No marine headlines expected. Winds
up to 10-15 kts with seas 2-4 feet. Fair weather.

Rip Currents...
Southwest flow at 5 to 10 mph becomes south 10 to 15 mph with
occasional gusts up to 20 mph on Thursday. Breaking waves will
average 1 to 2 feet. As a result, there is a LOW risk for the
development of dangerous and life threatening rip currents on
Thursday.

On Friday, south winds increase to around 15 mph with 20 to 25
mph gusts. The flow will be a bit more onshore for most of New
Jersey as opposed to northern New Jersey and Delaware. As a
result, there is a MODERATE risk for the development of
dangerous and life threatening rip currents for New Jersey
beaches from coastal Ocean county south to Atlantic Coastal
Cape May county and a LOW risk for the development of dangerous
and life threatening rip currents for eastern Monmouth county
and Delaware beaches. Breaking waves will once again average 1
to 2 feet.

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

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

&&

$$

SYNOPSIS...DeSilva/Wunderlin
NEAR TERM...Wunderlin
SHORT TERM...Deal
LONG TERM...Deal
AVIATION...Deal/DeSilva/MPS/Staarmann/Wunderlin
MARINE...Deal/DeSilva/MPS/Wunderlin