151
FXUS61 KPHI 151018
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
618 AM EDT Tue Jul 15 2025

.SYNOPSIS...
A very warm and humid airmass will be over the region this week
with multiple rounds of showers and thunderstorms expected. A
cold front will stall within the vicinity of the area through
Wednesday before lifting back northward as a warm front on
Thursday. A cold front passes through the region on Friday with
high pressure building in on Saturday. Another cold front then
approaches early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Showers and thunderstorms early this morning have primarily
moved off the coast with exception of the immediate Delaware
coast. Residual showers may continue for the next several hours
before diminishing. Otherwise, just some low clouds, mist and
some occasional patchy fog reside elsewhere.

The main story today will be with the slowly advancing cold
front that is tracking across the area. Guidance yesterday
suggested that the front would make it south of the area,
however guidance this morning suggests otherwise. It now appears
that the front will stall out the area today. For areas south
and east of the front today, it is expected that another round
of potentially heavy rain is possible. However, the main upper
level dynamics will be displaced further east so any heavy
precipitation will be mainly focused along any residual outflow
or sea breeze boundaries. WPC has outlooked most of our Delmarva
counties in a SLIGHT risk today for excessive rainfall. Have
considered a Flood Watch in these areas, but overall nature of
convection seems to be sporadic and isolated in nature. Further
north, the remainder of the area lies in a MARGINAL risk for
excessive rainfall. Highs today will primarily be in the mid to
upper 80s under partly cloudy skies where heat indicies are
expected to top out in the low to mid 90s.

Any convection that does develop today, should begin to wane
and diminish around sunset with the loss of diurnal heating.
Perhaps a few showers can linger into the overnight hours, but
primary threat will come to a close. Skies should be mostly
clear early, but an increase in clouds is expected overnight as
another round of low stratus may develop after midnight. Another
warm night is expected, with lows mainly in the 70s; upper 60s
in the Poconos.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
Unsettled weather along with very warm and humid conditions
will continue through Thursday. Several rounds of showers and
thunderstorms can be expected, with locally heavy rainfall
leading to flash flooding being the primary threat. On Thursday,
there is also a concern for extreme heat.

The stalled frontal boundary will begin to lift north on
Wednesday, but its exact placement remains uncertain at the
moment. The shortwave ridge will still be overhead on Wednesday,
and this could act to introduce some dry mid level air into the
equation. Synoptic forcing will not be strong, and shear will
again be weak. At least scattered to numerous showers and
thunderstorms should develop again into the afternoon and
evening due to the diurnal instability and lack of any
significant subsidence or CIN. PoPs remain around 50-80% for our
inland areas, greatest northwest of I-95.

No severe probabilities are currently included from SPC, but
there could be an isolated damaging wind gust from any stronger
thunderstorms that develop. PWats will again by high around 2"
or so, so the tropical downpours and locally heavy rainfall will
remain the primary hazard. The latest excessive rainfall
outlook from WPC includes a Slight Risk (2/4) for portions of
eastern PA and northern NJ, mainly along and north of the I-78
corridor.

On Thursday, southwesterly flow will bring back warm air and
moisture advection resulting in heat index values approaching
100 degrees in many areas. This is anticipated to be the
warmest day of the week (unless the cold front on Friday is
later than currently expected). A Heat Advisory will need to be
considered for Thursday across portions of the area in a future
update. There will again be chances of diurnally driven showers
and thunderstorms on Thursday, again focused mainly northwest
of I-95. Synoptic forcing is again not very strong, and deep
layer shear will be weak. A lot of uncertainty regarding the
convective environment for Thursday, and we currently have no
threats outlooks by WPC or SPC. PoPs are mostly 30-60%.

Thursday night will be the warmest night of the week, with low
temperatures mainly in the mid to upper 70s.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
Friday could be another hot day depending on the timing of the
next cold front. Latest guidance shows the front crossing
through the region late in the day, and into the overnight hours
on Friday. If that timing holds, most of the area (aside from
Delmarva) may be a degree or two lower on Friday as compared to
Thursday. This front may also act as a focusing mechanism for
thunderstorms and associated convective hazards, but as with
Thursday, uncertainty is high regarding any of these threats.
PoPs are near 40-60% for much of the area.

Heading into the weekend, Saturday should experience the lowest
chance of convection with a surge of slightly drier air, lower
instability, and some subsidence from the departing trough.
Temperatures returning back closer to normal, and a
comparatively nice Saturday looks to be shaping up with highs in
the mid 80s and lower humidity compared to this week. Chances
for convection should increase again some for Sunday as the
boundary start lifting north with return flow.

&&

.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Through 12Z...Mainly MVFR/IFR conditions expected. Rain showers
come to an end with low stratus and mist developing after
06-08Z at all terminals. Winds light and variable, becoming calm
at times. Low- moderate confidence.

Tuesday...Lingering MVFR/IFR ceilings, should improve to VFR by
the afternoon. Isolated showers and possibly a thunderstorm in
the afternoon, so have included VCSH for KILG/KMIV/KACY for now.
Temporary VSBY/CIGs restrictions possible in heavier showers.
Light and variable winds early, settling out of the south around
4-7 kt. Moderate confidence.

Tuesday night...Primarily VFR expected, with some low clouds
possibly developing after 06Z. Light southerly winds around 5 kt
or less. Moderate confidence.

Outlook...

Wednesday through Saturday...Overall, prevailing VFR
conditions. However, afternoon and evening SHRA/TSRA may result
in brief restrictions daily. Restrictions conditions are also
possible overnights/early mornings due to low clouds and fog,
but uncertainty remains on this potential, so confidence is low
on any daily details.

&&

.MARINE...
No marine headlines are in effect through tonight. South-
southwest winds around 5-10 kt this morning, increase to 10-15
kt this afternoon into tonight. Seas around 2 feet. Scattered
showers and thunderstorms possible through tonight, which may
cause locally gusty winds in excess of 34 kt.

Outlook...

Wednesday through Saturday...Winds and seas should stay below
Small Craft Advisory criteria through this period. Showers and
thunderstorms are possible daily, primarily in the late
afternoon and evening hours.

Rip Currents...

For today, southerly winds around 5-10 mph with breaking waves
around 1-2 feet, and an easterly swell at 6-7 seconds in length.
As a result, have maintained a LOW risk for the development of
dangerous rip currents at all beaches.

For Wednesday, south-southwesterly winds increase to around
10-15 mph with breaking waves around 1-3 feet, and an easterly
swell at 8-9 seconds in length. As a result, have upgraded Cape
May and Atlantic Counties to MODERATE, and maintained a LOW risk
for the development of dangerous rip currents for Monmouth,
Ocean and Delaware Beaches.

Rip currents occur often in the vicinities of jetties and piers
and the speed of the currents are generally maximized at low
tides.

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

&&

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

&&

$$

SYNOPSIS...DeSilva
NEAR TERM...DeSilva
SHORT TERM...Johnson/Staarmann
LONG TERM...Johnson/Staarmann
AVIATION...DeSilva/Johnson/Staarmann
MARINE...DeSilva/Johnson/Staarmann