273
FXUS61 KPHI 291941
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
341 PM EDT Sun Jun 29 2025

.SYNOPSIS...
A weak cold front near Delmarva and southern New Jersey will
stall out there tonight. The front will then return northward as
a warm front Monday into Monday night 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.

&&

.NEAR TERM /THROUGH MONDAY/...
Warm and humid day ongoing. Most of the area should remain dry
today, though some showers and thunderstorms are possible near the
coast of both New Jersey and Delaware. Some convection is likely to
develop along the sea and bay breeze (isolated cells have already
popped). Only around a 30-40% PoP though as cells will be scattered
in coverage. A MARGINAL (1/5) risk is in place for the southern half
of the area. While shear is near zero, instability is modest and
can`t rule out a strong downdraft producing some damaging wind
gusts. Convection dies off with the loss of daytime heating and most
of the night should be dry save for a few light showers near the
stalled front over the region. Along and south of the front that
should be positioned near I-76 and I-195 will be mild and muggy
tonight with lows in the low to mid 70s. For the northern stretches
of the area, expect temperatures to fall into the 60s.

For tomorrow, 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, but still only around 30-50% PoP
over 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 HRRR has been hinting at which is a touch
concerning).

In terms of temperatures for tomorrow, highs get into the upper 80s
to around 90. Tomorrow marks the last day of lower Heat Advisory
criteria for the urban corridor (> 96 Heat Index for two hours). A
Heat Advisory was considered but dew points should mix out a bit to
keep Heat Indices around 94-95.

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
On Monday night, the stalled out front starts to move northward as a
warm front and this continues into Tuesday. This will lead to
scattered showers and thunderstorms Monday night into early Tuesday
morning. Lows Monday night will be in the upper 60s to mid 70s.

Attention then turns to 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 low 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 morning activity 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 has added 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 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.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Synoptic Overview...An upper-level trough is forecast to move into
much of the Northeast by midweek. This trough looks to become
reinforced as it remains across much of the Northeast through the
end of this week. At the surface, a high pressure system builds in
late Wednesday into Thursday before settling over our area on
Friday.

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. Our Tuesday cold front should
be south and east of our area by midday 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 the remainder of Wednesday. On Thursday, a
weak cold front looks to sink southward during the afternoon and
evening. This cold front looks to set off some showers and
maybe an isolated thunderstorm for areas near and NW of I-78.

For Friday into Saturday...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. Overall, looks like a nice
forecast for the 4th of July. Nice weather should continue into the
holiday weekend as the high pressure system remains in control.

&&

.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Rest of Today (through 00z)...Primarily VFR. 20-40% chance of
showers and thunderstorms at KMIV/KACY which could result in
brief restrictions. Winds out of the west around 5-10 kt.
Moderate confidence.

Tonight...Primarily VFR through 06z. Patchy fog developing
around the area. Kept some terminals VFR but added in a TEMPO
group at KRDG/KILG/KMIV/KACY where probabilities of MVFR VSBYs
are around 30-40%. Probabilities are less around KPHL and points
north, only around 15-20%, so kept out for now. Cannot rule out
some visibility restrictions though. Winds light and variable.
Moderate confidence.

Monday...Primarily VFR. Any fog 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.

Outlook...

Monday Night...Primarily VFR. Restrictions possible though with
scattered showers and thunderstorms (40-60%).

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.

&&

.MARINE...
Sub-SCA conditions expected through tomorrow. A few showers and
thunderstorms possible later this afternoon and tomorrow
afternoon.

Outlook...

Monday night...No marine headlines expected. Some showers and
thunderstorms possible (20-30%).

Tuesday into Tuesday night...SCA conditions possible with wind
gusts near 25 kts and seas reaching 5 feet. Showers and
thunderstorms for the afternoon into Tuesday night (60-80%).

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

Rip Currents...

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 Monday, winds become more southerly 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 the NJ Shore and went LOW risk for
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...Guzzo/Hoeflich
NEAR TERM...Hoeflich
SHORT TERM...Guzzo
LONG TERM...Guzzo
AVIATION...Guzzo/Hoeflich
MARINE...Guzzo/Hoeflich