150
FXUS61 KPHI 141541
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
1141 AM EDT Fri Jun 14 2024

.SYNOPSIS...
A cold front crosses our area late this afternoon into tonight.
High pressure begins to build in later tonight and then it remains
in place over the region through the weekend. A warm front
lifts through Monday, but surface high pressure looks to control
our weather through at least the middle of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1135 AM, issued a quick update primarily to increase the
PoPs quite a bit for the next few hours mainly across the
Pocono region into northwestern New Jersey. An area of more
organized showers continues to advance east-northeastward
associated with what appears to be a weak shortwave and surface
trough. Much of the high-resolution guidance is not capturing
these showers well so far. In addition, increased the cloud
cover in that area faster. A stronger wave is across western
Pennsylvania as of this writing and this looks to be what much
of the guidance is focusing on for convective development
through the afternoon.

Otherwise, today starts off rather tranquil before a round of
showers and thunderstorms arrive for the second half of the
day. An upper-level trough is forecast to arrive later today,
bringing with it a cold front that will push through from west
to east this afternoon and evening. While the parent trough is
farther north, the southern portion of it has stronger shortwave
energy and is timed during peak heating across our region.
Ample instability is forecast to be in place (MLCAPE up to 1500
J/Kg) given air temperatures forecast to be in the 80s with
even some lower 90s and dew points in the 60s. The model
forecast soundings show a well mixed and warm boundary layer in
the afternoon and early evening. This results in an inverted-V
profile in the lower levels and thus increasing the downdraft
instability (DCAPE). Low-level lapse rates are rather favorable
as well, with around 9.0 C/km in the 0-3km layer, moderating to
around 6.0 C/km in the 3-6km layer. This all said, the limiting
factor is expected to be deep layer shear, with rather weak flow
in the low and mid levels and stronger winds in the upper
levels. The best shear is also displaced north and west of the
region.

Putting this all together, convection is forecast to develop to our
northwest and west and then propagate east and southeastward during
the afternoon and evening along and ahead of the cold front. While
coverage and timing does vary some among the guidance suite,
convection should organize into a few clusters or a broken line as
it shifts into and across our area, with this possibly weakening
near and especially south and east of I-95. This will depend on the
timing as southerly flow ahead of the convection and front will
bring some marine influence into portions of the coastal plain.
Locally damaging winds are the main severe weather threat especially
with stronger cores aloft (along with some mid level dry air)
enhancing the downdraft/downburst potential. Freezing levels look to
be on the higher side, however some hail cannot be ruled out with
some stronger updrafts. The precipitable water values are forecast
to be approaching 2 inches for a time ahead of the cold front, and
therefore high rainfall rates should occur with the strongest
convection for a time. The flash flooding risk however looks to be
low overall as storms should be on the move, however there is a non-
zero risk focused across mostly our northern and western zones.

The convection looks to be shifting offshore or weakening during the
evening hours with the severe thunderstorm risk ending. Some drier
air then starts to arrive from the northwest in the wake of the cold
front by later Friday night with at least some partial clearing also
starting to arrive. Overnight lows will cool into the upper 50s to
mid 60s.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
Surface high pressure will dominate over the region for the duration
of the short term; a dry and quiet forecast is on tap for the
weekend.

Not much to write home about regarding this forecast! Highs mainly
in the low to mid 80s for Saturday; highs just a bit warmer for
Sunday, by about 1-2 degrees. Very comfortable RHs expected for
both days with plenty of sunshine. Overall, a stellar weekend!

A sea-breeze will likely develop on Sunday given the weak synoptic
flow in the forecast. This sea-breeze could penetrate well in-land
by the late afternoon into evening hours.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
Summary...Hot but mainly dry forecast.

The synoptic pattern and evolution is nearly certain for the long
term. An upper-level ridge over the eastern CONUS Monday will build
to the north with time. By the Wednesday time frame, the strong
ridge will look to be centered directly over the northeastern CONUS
and will likely stay in place for quite a bit. The ensembles suggest
it is not until around the time frame of Friday that the ridge and
its associated axis will begin to break down a bit.

Overall, heights will only build over the region with time Monday
onwards. We could see heights of 594-600 dam over us for Wednesday.
At the surface level, high pressure centered offshore Monday will
move eastward with time as a warm front lifts over the region. Even
still, surface high pressure looks to largely control the region
through the duration of the term. Though some rounds of shortwave
energy may pester the region for much of the week, any precipitation
development should be largely suppressed given the pattern.

We are mainly looking at a dry forecast into Thursday with
temperatures potentially getting warming each day. High
temperatures may touch the low 90s for Monday, but widespread
highs in the 90s should be anticipated at this point for
Tuesday, Wednesday, and Thursday. It is still a little too early
to really discuss any potential for heat headlines at this
point, but the potential will only grow with time as the week
progresses.

&&

.AVIATION /16Z FRIDAY THROUGH TUESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

Rest of today...VFR for much of the time, however areas of sub-
VFR conditions later in the afternoon and evening as showers
and thunderstorms move through with a cold front. South to
southwest winds around 10 knots, becoming west later in the
afternoon at KRDG and KABE. A TEMPO group included to reflect
sub-VFR visibilities due to heavier rain with thunderstorms.
Low confidence with the timing details.

Tonight...Areas of sub-VFR conditions with some showers and
thunderstorms, then conditions improve overnight. Westerly
winds will become more northerly 5-10 knots. Low confidence.

Outlook...

Saturday through Tuesday...VFR with no significant weather.

&&

.MARINE...
Through tonight, the conditions are anticipated to remain below
Small Craft Advisory criteria. Southerly winds should be the
strongest at times across the northern New Jersey coastal waters
and possibly up Delaware Bay. However, given much warmer air
moving over the cooler waters, mixing should be more limited and
since it looks marginal opted to keep the conditions below
advisory criteria. Some showers and thunderstorms should arrive
late this afternoon and especially tonight, and some storms
could produce locally gusty winds. Winds turn more northerly
around 10 knots tonight behind the front.

Outlook...

Saturday through Tuesday...No marine headlines expected. Fair
weather.

Rip Currents...

Today, southerly winds 10 to 20 mph. The flow will be a bit
more onshore for most of New Jersey as opposed to Delaware.
Additionally, guidance shows a 2 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 be around 2 to 3
feet.

Winds turn offshore for Saturday, with a LOW risk for the
development of dangerous rip currents everywhere.

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...Gorse/MJL
SHORT TERM...Wunderlin
LONG TERM...Wunderlin
AVIATION...AKL/Gorse/MJL/Wunderlin
MARINE...AKL/Gorse/Hoeflich/Wunderlin