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760
FXUS61 KPHI 300821
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
421 AM EDT Mon Jun 30 2025

.SYNOPSIS...
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The stalled front across the southern half of the region will
slowly return northward as a warm front through tonight
followed by a cold front later Tuesday. High pressure builds
closer later Wednesday into Thursday before settling over our
area on Friday and into the weekend.
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&&

.NEAR TERM /THROUGH TONIGHT/...
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Isolated showers or a thunderstorm will remain possible
early this morning for southern New Jersey, Delaware, and
eastern Maryland, however, most places will remain dry. Some
cloud coverage is developing across the southern half of the
region, and there could also be some patchy light fog/mist
develop across the area as well.

For the daytime hours, that stalled front lifts north as a warm
front, putting the area fully into the warm sector ahead of the
cold front on Tuesday. Modest destabilization will occur under
mostly sunny skies to start the day. This will result another
round of scattered showers and thunderstorms developing as
instability builds on the order of 2000+ J/kg of SBCAPE. Shear
increases a bit compared to today with mid-level flow
strengthening ahead of an approaching trough. Convection will be
a tad more widespread compared to today as well given stronger
forcing and PoPs have increased to 65-75% across the
southwestern half of the area. Although shear increases, it
will be the limiting factor for severe potential. Given tall and
skinny CAPE profiles though, cannot rule out a few stronger
downbursts producing damaging wind gusts. SPC has most of the
region in a MARGINAL (1/5) risk for severe thunderstorms. Slow
moving convection could also result in some flash flooding,
especially if developing over a more urban area (something the
latest CAM guidance continues to hint at which is a touch
concerning). WPC has a MARGINAL risk (1/4) for excessive
rainfall leading to flash flooding for most of the area as well.

In terms of temperatures this afternoon, highs get into the
upper 80s to low 90s. Today marks the last day of lower Heat
Advisory criteria for the urban corridor (> 96 Heat Index for
two hours). Confidence has increased that we will hit this
criteria across the urban corridor today with mixing looking a
bit more limited and a Heat Advisory was issued as a result.

Heading into tonight, the warm front looks to clear northward of
the region and convection will slowly wane with its departure
and the loss of daytime heating, though some isolated showers or
a thunderstorm could linger, particularly across the northern
half of the region. Lows mainly in the 70s are expected.
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&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
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Our focus in the short term remains the potential for strong to
potentially severe convection developing later in the day
Tuesday. During the day Tuesday, we will be well into the warm
sector as that warm front from Monday night has moved well to
the north. In the upper levels, 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.

In terms of the set-up for the second half of Tuesday, shear will be
on the rise, especially compared to some of our recent severe
weather days. Also, highs in the upper 80s to low 90s with dew
points in the low to mid 70s will provide an environment for
growing instability ahead of the cold front. At this time, there
is still some uncertainty on how well the shear and areas of
higher CAPE overlap along with the timing of the cold front.
Another uncertainty is the morning convection. If the early morning
activity remains more widespread and takes longer to dissipate
and clouds linger longer, this will have impacts on how well we
destabilize before the cold front. Right now, the morning
activity looks to be done by the mid-morning hours of Tuesday
with enough time to get moderate instability. The latest severe
weather outlook continues with a Slight (2/5) risk for most of
our area with the remainder of the area in a Marginal (1/5)
risk. The primary threat will be damaging wind gusts.

One other key impact point for Tuesday is a flash flooding threat.
All of the area is in a Marginal (1/4) with Delmarva and
portions of southern New Jersey and southeastern Pennsylvania
in a Slight (2/4) risk in the Excessive Rainfall Outlook with
the concern for localized flash flooding. PWAT values will rise
to 2-2.5 inches with warm cloud depth of 10-12 kft, so the
signal is there for the convection to be sufficient rainfall
producers. The good news is that the convection will be moving
but any training of showers or thunderstorms could lead to
increased concern for localized flash flooding. There is also a
signal for some frontogenetic forcing with the cold front which
could also enhance the precipitation rates with the convection.

The severe threat looks to come to an end between 00Z-03Z Wednesday,
but given the front slowing down Tuesday night, it is still near the
coastal areas by Wednesday morning. This will continue to lead to
the potential for lingering coverage of some showers into Wednesday
morning. Lows Tuesday night are in the low 60s to low 70s.

Heading into Wednesday, our Tuesday cold front should be south
and east of our area by midday, 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 the remainder
of Wednesday.
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&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
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The upper level trough looks to become reinforced as it remains
across much of the Northeast through the end of the work week
before moving offshore over the weekend. At the surface, a high
pressure system continues to build in Thursday before settling
over our area on Friday and Saturday and moving offshore on
Sunday.

While high pressure will be increasingly in control, a weak
cold front looks to sink southward during the afternoon and
evening on Thursday. This cold front looks to set off some
showers and maybe an isolated thunderstorm for areas near and NW
of I-78. The remainder of the forecast looks dry until Sunday
when the high moves offshore.

Daytime temperatures in the 80s for most through Saturday, with
temperatures look to warm closer to 90 on Sunday. Dew points
are forecast to be in the low to mid 60s before increasing to
around 70 on Sunday. Overall, the most pleasant day does look to
be Friday which should make for a nice forecast for the 4th of
July.
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&&

.AVIATION /08Z MONDAY THROUGH FRIDAY/...
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The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Early this morning...Mostly VFR conditions. Patchy fog/mist is
possible through daybreak along with isolated showers/storms.
Mostly MVFR visibilities are expected if any fog/mist develops,
but a couple of sites may develop IFR visibilities if a heavy
shower or storm moves through. Light and variable winds.
Moderate confidence.

Today...Primarily VFR. Any fog/mist mixes out by 12z. Winds
pick up out of the south around 5-10 kt by the late morning.
Chance for scattered showers and thunderstorms (30-50%) which
could bring brief restrictions to all terminals. Moderate
confidence.

Tonight...Primarily VFR. Restrictions possible though with
scattered showers and thunderstorms (40-60%). Winds remaining
out of the south around 5-10 knots. Moderate confidence.

Outlook...

Tuesday through Tuesday Night...Restrictions likely (70-90%)
with showers and thunderstorms moving through, mainly in the
afternoon and evening.

Wednesday through Friday...VFR. No significant weather.
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&&

.MARINE...
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Sub-SCA conditions expected through today. A few showers and
thunderstorms possible in the afternoon. Seas around 2 feet.

Near-SCA conditions possible tonight with wind gusts increasing
to around 20-25 knots. A few showers and thunderstorms remain
possible. Seas build to 3-4 feet.

Outlook...

Tuesday into Tuesday night...SCA issued for Atlantic Ocean zones
with wind gusts of 25-30 kts and seas reaching up 6 feet
expected. Showers and thunderstorms for the afternoon into
Tuesday night (60-80%).

Wednesday into Friday...Sub-SCA conditions expected.

Rip Currents...

For Monday, winds become more southerly to southeast and the
period will remain 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 most of the NJ Shore and went LOW
risk for Delaware Beaches and coastal Ocean County.

For Tuesday, winds become more south-southwest and the period
will be around 7 seconds with breaking waves around 1 to 3
feet. Thus, we have a MODERATE risk for the development of
dangerous rip currents for most of the NJ Shore and went LOW
risk for Delaware Beaches and eastern Monmouth County.

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

.PHI WATCHES/WARNINGS/ADVISORIES...
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PA...Heat Advisory from noon today to 8 PM EDT this evening for
     PAZ070-071-102-104-106.
NJ...Heat Advisory from noon today to 8 PM EDT this evening for
     NJZ015-017>019.
DE...Heat Advisory from noon today to 8 PM EDT this evening for
     DEZ001.
MD...None.
MARINE...Small Craft Advisory from 11 AM Tuesday to midnight EDT
     Tuesday night for ANZ450>455.
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&&

$$

SYNOPSIS...AKL/Guzzo/Hoeflich
NEAR TERM...AKL/Hoeflich
SHORT TERM...AKL/Guzzo
LONG TERM...AKL/Guzzo
AVIATION...AKL
MARINE...AKL