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694
FXUS61 KPHI 121851
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
251 PM EDT Wed Jun 12 2024

.SYNOPSIS...
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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.
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&&

.NEAR TERM /THROUGH THURSDAY/...
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Seasonable weather will continue for the rest of today. Temperatures
are currently in the 70s to around 80 degrees with some fair weather
clouds across much of the region.

High pressure will begin to make its way off the coast later tonight
before settling over the northwest Atlantic on Thursday. This will
keep conditions dry and skies clear as surface flow gradually
becomes more south-southwesterly later tonight. Lows tonight will be
pretty close to normal in the mid 50s to low 60s.

For Thursday, expect another sensible weather day with mostly clear
skies with just some more diurnal cumulus in the afternoon. The
biggest difference for Thursday is that we will be noticeably
warmer than today due to an increase in warm air advection and
increasing heights aloft. All in all, a mild day is in store
with highs in the 80s, with temps in the upper 70s near the
shore.
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&&

.SHORT TERM /THURSDAY NIGHT 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 /19Z WEDNESDAY THROUGH MONDAY/...
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The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

Rest of Today...VFR with mostly clear skies. WNW winds around 5-10
kt. High confidence.

Tonight...VFR with clear skies. WSW winds around 5 kt will become
light and variable at times. High confidence.

Thursday...VFR with mostly clear skies. S-SW winds around 5-10 kt
gusting around 15-18 kt in the afternoon. 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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No marine headlines expected through tonight. South-southwest winds
around 10-15 kt with seas around 2 feet. On Thursday, south winds
increase up to 13-18 kt with gusts up to 23 kt in the afternoon.
Seas around 3-4 feet. SCA conditions are possible due to gusty
winds, but are expected to remain below criteria.

Outlook...

Thursday night through Friday night...SCA conditions possible
Thursday night into Friday due to winds gusting up to 20-25 kts
and seas of 3-5 feet. Fair weather expected on Thursday night
with 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...

A LOW risk for the formation of dangerous rip currents
continues through Thursday. Southerly winds will only have a
small component onshore for most of the coast. Additionally,
expecting more short period, wind driven waves.

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...DeSilva
SHORT TERM...Deal
LONG TERM...Deal
AVIATION...Deal/DeSilva
MARINE...Deal/DeSilva