557
FXUS61 KPHI 130817
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
417 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/...
As of 3:20AM...No changes to the forecast at this time. Previous
discussion remains.

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 SATURDAY NIGHT/...
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. Latest 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. The
full suite of hi res convective-allowing models depicts modest
instability developing during the afternoon, around 1000 J/kg of
MUCAPE, 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 with severe
thunderstorm wind gusts being the main threat. As a result, SPC
has placed areas north and west of the I-95 corridor in a Slight
Risk for severe weather with the rest of the region in a
Marginal Risk. 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 through Friday until the cold front pushes
through. This leads highs before the front Friday warming into
the upper 80s to low 90s, and then down into the upper 50s to
low 60s Friday night.

High pressure builds in from the north and west on Saturday,
ushering a rather tranquil weekend. Highs during the afternoon
will be in the low-to-mid 80s with nighttime lows dipping into
the mid 50s to right around 60.

&&

.LONG TERM /SUNDAY 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 for several days in a row. While global guidance
is still rather spread out with just how hot it will get across
the region next week, guidance across the board has been fairly
consistent with the building high pressure and increasing heat
through the week with a high likelihood of temperatures
lingering well into the 90s for a number of days. At this
point, it is certainly not too early to start thinking about
your cooling options for next week. For anyone hoping for
temporary relief from precipitation chances, at the moment,
chance for this remain rather low. While there are some pieces
of shortwave energy tracking through the region during the week,
the overall chance for showers is fairly capped (10-15%) due to
the very weak forcing from these shortwaves. 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 /08Z THURSDAY THROUGH MONDAY/...
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 Monday...VFR with mostly clear skies. No
significant weather expected.

&&

.MARINE...
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 Monday...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

&&

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

&&

$$

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