696
FXUS61 KPHI 272303
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
703 PM EDT Fri Jun 27 2025

.SYNOPSIS...
A front well to our south and west will gradually lift
northward as a warm front Saturday, followed by a weak cold
front stalling nearby on Sunday. The front then shifts northward
as a warm front Monday followed by a cold front later Tuesday.
High pressure builds closer later Wednesday into Thursday before
settling over our area on Friday.

&&

.NEAR TERM /THROUGH SATURDAY/...
Satellite imagery and surface obs indicate the back door cold
front has stalled in eastern Virginia. Despite the front being
well south, spotty showers have developed across the region
thanks to elevated instability, warm/moist advection aloft and
weak upper-level impulses. Expect this to more or less continue
thru tonight.

The front is expected to start pushing back northward as a warm
front ahead of another cold front tonight, possibly causing
some fog to develop particularly across southern/coastal areas
as it does so later tonight into early Saturday. Temperatures
won`t change much, perhaps even warming late tonight as the
front approaches from the south.

The warm front should then push north of the area toward midday
Saturday, resulting in clouds breaking for some sun with a very
warm and humid day across the region. With temps likely to
approach 90 and dew points likely in the 70s, heat indices will
likely reach our early-season heat advisory thresholds across
the metro, so have issued a metro-only heat advisory for heat
indices of 96-99. Heat indices likely pass 100 across parts of
the Delmarva, but the all-year criteria there is 105, so no
advisories necessary.

Some spotty sea-breeze showers and storms may develop across NJ
and DE during the midday and afternoon Saturday, but the main
focus is the next cold front which approaches from the northwest
late in the day. With decent CAPE and shear but nothing too
crazy, for now we remain in a marginal outlook for severe
weather, with damaging winds being the main threat. Depending on
guidance trends, wouldn`t be surprised if this ends up as a
slight with a severe thunderstorm watch at some point later
tomorrow, but confidence isn`t there yet. Gotta see how
destabilized we get after we break out of this marine air mass
first.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
A more zonal flow aloft from the Midwest to the Northeast is
forecast to be in place Saturday night into Sunday. A shortwave
trough embedded in this flow looks to slide by to our north into
Saturday evening. Surface low pressure tied to this feature
tracks well to our north, however a weak cold front associated
with it arrives into our area Saturday evening. This front
should tend to stall in our vicinity Sunday as the flow remains
mainly zonal aloft. Some showers and thunderstorms should
accompany the front into Saturday evening, a few which could
produce locally damaging wind gusts. Some drier air will also
start to arrive from the west in the wake of the front later
Saturday night, although much of the area will remain on the
muggy side Saturday night.

Some additional drying is forecast to take place on Sunday with
dew points dropping into the 60s for much of the area, although
a more humid feel may linger across parts of Delmarva. The
extent of the drying will depend on where the surface front sets
up. There does not appear to be a real strong focus for
convective development during Sunday, although a few showers or
thunderstorms cannot be ruled out mainly across Delmarva where
deeper moisture may remain longer. High temperatures are
forecast to be well into the 80s for the majority of our area,
and with lower dew points the heat indices are forecast to be
lower Sunday afternoon compared to Saturday afternoon.

As we go through Monday, an upper-level trough across the
Midwest and adjacent Canada is forecast to shift eastward and
amplify some as it approaches the Northeast. A front warm lifts
north across our area on Monday. A few showers or thunderstorms
are possible with the northward movement of the warm front, with
the greatest chance (40- 50 percent) mainly across southwestern
parts of our forecast area. Temperatures will make a run at 90
degrees for many areas and with dew points on the rise, heat
indices will also be on the increase. As of now, the forecast
heat indices are below Heat Advisory criteria (even for the the
I-95 urban corridor, Wilmington to Philadelphia to Trenton,
where the criteria is lower through June 30th).

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
Summary...Some showers and thunderstorms to start, otherwise no
extreme heat forecast.

Synoptic Overview...An upper-level trough is forecast to move
into much of the East by later Tuesday. This trough looks to
become reinforced as it remains across much of the East through
the end of next week. At the surface, a cold front moves through
later Tuesday, then high pressure builds closer later Wednesday
into Thursday before settling over our area on Friday.

For Tuesday...An upper-level trough is forecast to shift
eastward and amplify some as it overspreads the Northeast and
Mid-Atlantic. This will drive a cold front across our region
later Tuesday. An uptick in the shear is forecast, especially
across Pennsylvania and New Jersey where the stronger mid level
flow is forecast to be. Moderate instability may develop and if
this overlaps with the greater shear, a favorable area for
severe thunderstorms (damaging winds) may develop Tuesday
afternoon and/or early evening. The details will depend on the
magnitude of the shear and instability as well as the timing of
the cold front and upper-level trough axis. Temperatures are
forecast to top out between 85-90F for much of the region,
although if cloud cover and convection hold off long enough the
highs could be a little higher than forecast. While it will be
rather humid, extreme heat is currently not forecast.

For Wednesday and Thursday...The upper-level trough across the
Northeast and Mid-Atlantic may tend to sharpen again as
additional energy rounds its base. The cold front should be
south and east of our area to start Wednesday, and while
temperatures do not look to drop much, the dew points are
forecast to lower some in the wake of the cold front. Despite
the presence of the upper-level trough, less in the way of
deeper moisture should keep the instability lower as well. Given
surface high pressure building closer to our area with time,
the chance for any showers and thunderstorms at this time is
little to none.

For Friday...The upper-level trough is forecast to still be in
place with weak surface high pressure becoming more established
over our area. The return flow up the Ohio Valley will increase
the low-level warm air advection with a northeastward moving
warm front. The forcing for this, as of now, looks to remain
well to our west and therefore little in the way of shower
chances. Daytime temperatures in the 80s for most, and the dew
points are forecast to be in the low to mid 60s.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Rest of Today...Spotty showers could reduce vsby in spots below
VFR, with some mist along the southern NJ coast (ACY).
Otherwise, mostly MVFR due to cigs. Winds mostly easterly 5-10
kts with a few gusts up to 20 kts. High confidence.

Tonight...A continuation of low CIGS with scattered showers.
IFR likely with LIFR possible, perhaps intervals of VLIFR. Some
fog could also develop, most likely at ACY. Moderate confid.

Saturday... Lower CIGS and perhaps vsby early Sat then VFR
expected to return toward midday. Scattered showers/tstms with
lower CIGS/VSBYs in the afternoon, mainly late. Low confidence.

Outlook...

Saturday night...Local sub-VFR conditions at times possible
with a few showers or thunderstorms around, otherwise VFR.

Sunday...VFR overall.

Monday...A few showers and thunderstorms, with lower ceilings
and visibilities at times, are possible.

Tuesday...Showers and some thunderstorms probable with local
restrictions, especially in the afternoon and evening.

Wednesday...VFR overall.

&&

.MARINE...
Winds and seas across Delaware Bay and the southern ocean zones
diminished earlier, but seas have increased to near 5 feet
again across the ocean waters. We`ve expanded the SCA back
through the southern waters through midnight, by which point
conditions likely diminish, but remain easterly 10-15 kts with
seas 3-4 ft. Scattered showers and possibly an isolated t-storm
thru tonight. As of 630 PM, the fog is thickening along coastal
Delaware and southern New Jersey. This trend should continue
with areas of visibility 1 NM or less at times, so we`ve issued
a Dense Fog Advisory through noon Saturday to highlight this
threat.

Sub-SCA expected on Saturday with winds turning southerly
around 10 kts with seas 3-4 ft. Areas of marine fog early,
spotty thunderstorms possible mainly later.

Outlook...

Saturday night through Wednesday...The conditions are
anticipated to be below Small Craft Advisory criteria. A few
gusty thunderstorms possible mainly Saturday night and again
Tuesday afternoon/evening.

Rip Currents...

For Saturday, the flow turns southerly so there will be less of
an onshore component however the seas will continue to be
around 3 to 4 feet with a lingering onshore swell. For this
reason, we`ll continue with a MODERATE risk for the development
of dangerous rip currents for the NJ Shore and Delaware
Beaches.

For Sunday, seas lessen some and winds become more variable,
however the period will increase to around 9 seconds with
breaking waves around 2 to 3 feet. Thus, we`ll keep a MODERATE
risk for the development of dangerous rip currents for the NJ
Shore and Delaware Beaches.

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

&&

.TIDES/COASTAL FLOODING...
Even though the new moon was 2 days ago, persistent onshore
flow is expected to keep tide levels high again with tonight`s
high tide. Minor tidal flooding is now expected to reach
advisory levels for all sites along the Atlantic Ocean and
adjacent back bays, the Delaware Bay, as well as the tidal
portions of the Delaware River. Therefore a Coastal Flood
Advisory has been issued for these area. The areas along the
Chesapeake Bay should remain below minor flood levels.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Heat Advisory from noon to 8 PM EDT Saturday for PAZ070-071-
     102-104-106.
     Coastal Flood Advisory from 2 AM to 7 AM EDT Saturday for
     PAZ070-071-106.
NJ...Coastal Flood Advisory from midnight tonight to 4 AM EDT
     Saturday for NJZ016.
     Heat Advisory from noon to 8 PM EDT Saturday for NJZ015-
     017>019.
     Coastal Flood Advisory until 3 AM EDT Saturday for NJZ012>014-
     020>027.
     Coastal Flood Advisory from 2 AM to 7 AM EDT Saturday for
     NJZ017>019.
DE...Coastal Flood Advisory from midnight tonight to 4 AM EDT
     Saturday for DEZ001.
     Heat Advisory from noon to 8 PM EDT Saturday for DEZ001.
     Coastal Flood Advisory until 3 AM EDT Saturday for DEZ002>004.
MD...None.
MARINE...Dense Fog Advisory until noon EDT Saturday for ANZ431-451>455.
     Small Craft Advisory until midnight EDT tonight for ANZ450>455.

&&

$$

SYNOPSIS...Gorse
NEAR TERM...RCM
SHORT TERM...Gorse
LONG TERM...Gorse
AVIATION...Gorse/RCM
MARINE...AKL/Gorse/RCM/Staarmann
TIDES/COASTAL FLOODING...Robertson