831
FXUS61 KPHI 271345
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
945 AM EDT Thu Jun 27 2024

.SYNOPSIS...
In the wake of a cold front this morning, high pressure builds
toward our area tonight then arrives during Friday before shifting
offshore into Saturday. A warm front lifts north across our region
Saturday, followed by a cold front during Sunday. High pressure then
arrives for Monday and Tuesday before weakening and sliding offshore
Wednesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
The cold front has mostly moved offshore, although it is still
lingering across far southeast New Jersey coast and across
southern Delaware. It will continue shift farther offshore
through today. Behind it, stratocumulus clouds have begun to
develop this morning as morning heating has begun to mix the
boundary layer and clouds are forming near the low level
inversion. As this inversion mixes and lifts through the morning
and this afternoon, the cloud heights will lift. We may end up
with partly cloudy skies through the day.

Temperatures return to more seasonal levels today, topping off in
the mid to upper 80s. Surface dew points will fall into the upper
50s/near 60 during the afternoon as well.

High pressure over the Great Lakes this evening begins to build east
tonight and tranquil conditions will continue as a result. Lows
tonight will generally be in the low to mid 60s. However, in the
Lehigh Valley, northwest New Jersey, and southern Poconos,
temps look to get down into the mid to upper 50s.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
High pressure builds east across the Northeast on Friday then
weakens some and shifts offshore into Saturday. Tranquil conditions
expected during this time. Sunny and pleasant on Friday with
seasonably warm temperatures. Highs will be in the low to mid 80s,
though cooler at the coasts and in the mountains. Due to increasing
cloud cover, lows will be a few degrees warmer Friday night compared
to Thursday night.

On Saturday, low pressure will be moving across the Northern
Plains and into the northern Great Lakes. A warm front will
develop out ahead of this system, and that will lift through the
eastern third of the U.S. Saturday afternoon. Surface dew points
will rise into the 70s throughout much of the region, and with highs
in the 80s, heat index values will be in the low to mid 90s mostly
from the I-95 urban corridor southward across our Delmarva counties.
Shortwave energy passing through the region will spark off some
showers and thunderstorms in the afternoon, with locally heavy rain
and gusty winds being the primary threats. Lingering showers and
thunderstorms will continue Saturday night. It will be a warm and
humid night with lows in the 70s, though not much below 80 for the
urban I-95 corridor from Philadelphia to Wilmington and also into
Delmarva. In addition, surface dew points will be in the 70s which
will assist in holding temperatures up more and also result in
rather muggy conditions.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Hot and humid on Sunday with highs in the upper 80s to low 90s
(cooler along the coast and in the higher elevations of the
Poconos), but surface dew points will be in the 70s. This should
yield heat index values during peak heating Sunday afternoon to near
100 degrees (the highest values look to be from the urban I-95
corridor down into our Delmarva counties). A cold front approaches
from the west and with some increasing ascent results in at least
some showers and thunderstorms developing once again especially in
the afternoon. A slower arrival time of the cold front should result
in a longer time for instability to build, and convective initiation
could be assisted by a pre-frontal trough. Given enough shear and
instability combined with incoming ascent, there is the potential
for some thunderstorms to become locally severe with damaging winds.
In addition, increasing precipitable water values (potentially
nearing 2.5 inches) will support locally torrential rainfall and
therefore a localized flooding risk. The showers and thunderstorms
taper off Sunday night as the cold front works its way through the
region.

High pressure then builds in Monday and Tuesday before weakening and
shifting offshore into Wednesday. This will deliver a much less
humid airmass across the region along with cooler temperatures,
although developing warm air advection should start to boost the
temperatures Wednesday afternoon back well into the 80s with dew
points also climbing back into the 60s.

&&

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

Today...Stratocumulus clouds have developed and spread across
the area, and MVFR ceilings will likely affect all TAF sites
through around 16z, so a TEMPO group has been added for all TAF
sites. The cloud bases will lift by midday into the afternoon,
but a scattered to broken deck will likely remain through the
afternoon. Northwest winds 5 to 10 kt, with occasional gusts 15-20
kt in the afternoon are expected. A sea breeze may develop
around 21-23Z and turn winds more southwesterly at KACY and
possibly KMIV. High confidence overall, except lower confidence
in timing of improving conditions.

Tonight...VFR. Winds shifting to be mainly out of the north around 5
knots. High confidence.

Outlook...

Friday...VFR.

Saturday and Sunday...Some afternoon and evening showers and
thunderstorms will result in periods of sub-VFR conditions.

Monday...VFR.

&&

.MARINE...
Sub-SCA conditions are expected through tonight. Southwest
winds around 10 knots become northerly tonight and increase to
10-15 knots. A few gusts around 20 knots possible. Seas of 2-4
feet throughout the period.

Outlook...

Friday...The conditions are anticipated to be below Small Craft
Advisory criteria.

Saturday and Sunday...Small Craft Advisory conditions probable as
southerly flow increases ahead of a cold front. Showers and
thunderstorms may produce locally gusty winds.

Monday...The conditions are anticipated to be below Small Craft
Advisory criteria.

Rip Currents...

Today...West-northwest winds around 10 mph will become
southerly in the afternoon. Breaking waves of 2-3 feet for
southeast facing New Jersey beaches and 1-2 feet for the
remainder of New Jersey as well as Delaware beaches. Due to
higher waves along the southeast facing New Jersey beaches,
opted for a MODERATE risk for the development of dangerous rip
currents for Ocean, Atlantic, and Cape May. A LOW Risk for the
development of dangerous rip currents is forecast for Monmouth
County and the Delaware beaches.

Friday...Northeast to east-southeast winds 10-20 mph. Breaking
waves of 2-3 feet for all beaches. With more of an onshore flow and
winds being a bit greater than Thursday, opted to go with a
MODERATE risk for the development of dangerous rip currents for
the New Jersey and Delaware beaches.

For specific beach forecasts, visit weather.gov/beach/phi

&&

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

&&

$$

SYNOPSIS...Gorse/MPS
NEAR TERM...AKL/MPS/Robertson
SHORT TERM...Gorse/MPS
LONG TERM...Gorse/MPS
AVIATION...AKL/Gorse/MPS/Robertson
MARINE...AKL/Gorse/MPS