599
FXUS61 KPHI 121737
AFDPHI

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

.SYNOPSIS...
Weak surface high pressure controls the region through Thursday
night. A cold front approaches from the northwest Thursday
night into Friday and looks to cross through later Friday into
Friday night. High pressure builds in thereafter and holds
influence over the region into the beginning of next week.

&&

.NEAR TERM /THROUGH THURSDAY/...
As of 1:00pm...Little changes to the forecast needed as fair
weather clouds cover much of the area this afternoon. Previous
discussion remains below:

As today wears on, upper low will continue pulling away as
upper ridging builds in. There will be a warm front moving
across the region to usher in the warmer air. The front, mostly
aloft, will be accompanied by mainly mid and high clouds, so
not expecting a pure sunny day... more likely partly to mostly
sunny, as the main push of clouds with the front likely moves
across during the late morning into early afternoon. Regardless,
the return of sun and passing warm front should push temps back
to near 80 for much of the region.

Tonight, ridging and warm advection continues aloft. Thus,
expect temps to stay a few degrees warmer despite less cloud
cover, with upper 50s to low 60s for most.

&&

.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 TUESDAY/...
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 /18Z WEDNESDAY THROUGH MONDAY/...
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.

&&

.MARINE...
No marine headlines through tonight. Winds northerly to
westerly generally below 15 kts and seas of 1-2, occasionally up
to 3 feet.

Outlook...

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

&&

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

&&

$$

SYNOPSIS...Wunderlin
NEAR TERM...DeSilva/RCM
SHORT TERM...Deal
LONG TERM...Deal
AVIATION...Deal/DeSilva/Fitzsimmons/Johnson/RCM/Wunderlin
MARINE...Deal/DeSilva/Fitzsimmons/Johnson/RCM/Wunderlin