721
FXUS61 KPHI 131338
AFDPHI

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

.SYNOPSIS...
Weak surface high pressure centered offshore will still remain
in control through tonight. A cold front crosses our region
Friday afternoon into Friday night. High pressure then builds
in over the region and continues into the beginning of next
week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 935 AM, the low-level moisture is increasing mostly
across the coastal plain where the dew points are into the 60s.
These may lower some though this afternoon with vertical mixing.
This increased moisture should result in at least some cumulus
development through the afternoon. Plenty of warming on land
will add to a sea breeze through the day. No significant changes
were made with this update.

Otherwise, weak surface high pressure is centered offshore
however it remains extended over our region and will still
influence our weather tonight.

We will have some warm air advection today with a south to
southwest surface flow. Highs in the 80s are anticipated for
most areas, with it cooler along the coast with a sea breeze
and also in the higher terrain. There is some indication of some
upper-level shortwave energy being in place this afternoon/evening.
While the forecast continues to have no precipitation included
given the rather weak forcing and very low probability, a few
isolated showers cannot be ruled out entirely later today.

Mainly quiet conditions continue tonight with overnight lows in
the 60s.

&&

.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 /14Z THURSDAY THROUGH MONDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

Today...VFR. South to southwest winds increasing to around
10 knots, with some local gusts up to 20 kts possible this
afternoon. Moderate confidence.

Tonight...VFR. South-southwest winds around 5 knots. High
confidence.

Outlook...

Friday...Sub-VFR possible with showers and thunderstorms during
the afternoon/evening.

Saturday through Monday...VFR.

&&

.MARINE...
Today and tonight, southerly winds increase to 10-15 knots with
gusts to around 20 knots this afternoon/evening. Seas 2-4 feet.
Marine headlines are largely not anticipated. 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 5-10 mph becomes south 10-15 mph with occasional
gusts up to 20 mph today. Breaking waves will average 1 to 2
feet. Primarily a 1-2 ft 7-8 second short period swell from the
E-SE. As a result, there is a LOW risk for the development of
dangerous rip currents today.

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. That
said, strongest winds will be across northern New Jersey.
Additionally, guidance shows a 1 ft 9-10 second longer period
swell from the SE to SSE developing by the afternoon. As a
result, there is a MODERATE risk for the development of
dangerous rip currents for New Jersey beaches where the
coastline is more perpendicular or oblique to the longer period
swell. LOW risk for the development of dangerous rip currents
for the 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...Gorse/Wunderlin
SHORT TERM...Deal/MJL
LONG TERM...Deal/MJL
AVIATION...Gorse/MJL/Wunderlin
MARINE...Gorse/MJL/Wunderlin