872
FXUS61 KPHI 171856
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
256 PM EDT Thu Jul 17 2025

.SYNOPSIS...
A weak cold front will move through the region this evening,
with high pressure temporarily building in its wake. A series of
disturbances will bring unsettled weather this weekend, until a
stronger cold front clears the area Sunday. High pressure will
settle in to the area for the first part of next week.

&&

.NEAR TERM /THROUGH FRIDAY/...
A hot and oppressively humid day is ongoing with widespread
heat indices of 100-105 being observed across most of the
region. A Heat Advisory remains in effect through this evening.

Relief is on the way however in the form of a cold front
marching across Pennsylvania at this hour. This front could also
trigger a few showers and thunderstorms this afternoon and into
the evening. However, the forcing isn`t overtly strong, and
while we have around 3500-4500 J/KG of CAPE, shear isn`t
anything to write home about, with effective bulk shear around
20-25 kt over our area. Mid-level lapse rates are quite meager
as well, only around 6-6.5 C/Km. If something could get
organized, a strong to severe thunderstorm can`t be ruled out
with the amount of moist and unstable air in place. Steep low-
level lapse rates could also aid in stronger downdrafts.
Overall, the threat is rather marginal given the limiting
factors in play, and a MARGINAL (1/5) risk is in place for the
entire area. PoPs range from 20-40% along and west of the I-95
corridor and about 15-30% south and east. Main threat would be
damaging wind gusts from about 4 PM to 9 or 10 PM.

The cold front should swing through tonight with skies clearing
out some and humid air being swept out of the region. It starts
to feel more comfortable tonight as dew points fall quickly in
the wake of the front. Lows generally range from the upper 60s
to low to mid 70s. Areas in the Poconos could even get down into
the 50s.

While the cold front clears our area overnight, it will stall
out just to our south and east. This could result in more clouds
and a few showers/isolated thunderstorms across the Delmarva
peninsula and far South Jersey, areas that are in closer
proximity to the stalled boundary. Not expecting any severe or
hydro threats however. Elsewhere, it will be a rather quiet day
and much more comfortable than today as dew points will be in
the low to mid 60s for most spots, and even potentially into the
50s north of I-78. Highs are more seasonable, or even a few
degrees below normal for tomorrow-in the low to mid 80s.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
An upper-low initially over portions of the Hudson Bay and
northern Quebec will shift slowly southeastward through the
period. With ridging centered over the southeastern US, our
region will initially have weak zonal flow aloft and neutral
heights. Friday night, an area of low pressure passing to the
south could continue to bring lingering chances for showers
across portions of the Delmarva, but high pressure over New
England should keep most of the area dry. Friday night lows
should generally be in the mid-upper 60s, with a few low 70s
possible, outside of the Poconos where temperatures could fall
into the upper 50s.

A subtle shortwave embedded in the zonal flow regime should
pass through the area on Saturday. As the surface high shifts
east off of the coast, shower and storm chances will increase
across our entire area. As of right now, the greatest chance
appears to be from Saturday afternoon into much of Saturday
night. Instability looks to be quite limited with this system,
so severe weather is not anticipated at this time. However,
there will be enough moisture to work with to support at least
some potential for excessive rainfall. As such, the Weather
Prediction Center has introduced a Marginal Risk (1 of 4) across
most of our area for flash flooding.

As the upper-low shifts southeast through the weekend, it
should become more of an open trough with the axis pivoting
through northern New England Sunday night. A surface cold front
will approach the area from the northwest by Sunday evening.
Scattered showers and storms will be possible across much of the
area during the afternoon and evening hours ahead of the front.
Models are hinting at some instability and wind shear that
could lead to some severe potential, so this will need to be
monitored in the coming days.

The cold front appears likely to bring in a much more pleasant
airmass. While it may not drop temperatures too much, it should
help with the high moisture content which has contributed to the
oppressive nature of the recent heat.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
With high pressure over the area and the recent frontal passage
having reduced both temperatures and dewpoints across the area,
Monday and Tuesday should both be quite pleasant. Partly to
mostly clear skies and fairly light winds are expected.
Afternoon highs look to be in the low-mid 80s both days, with
overnight lows generally in the low 60s.

While no major storm systems are anticipated in the extended
period, it may become slightly more unsettled Wednesday into
Thursday, with at least low chances for afternoon storms
returning. In addition, we will likely see temperatures start to
warm again, with most locations seeing highs approaching 90
again by Thursday.

&&

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

Today...Primarily VFR, though brief restrictions possible as
scattered to isolated showers and thunderstorms develop later
this afternoon. Added VCTS groups to KRDG/KABE/KTTN for a few
hours this afternoon, with lesser chances at other terminals,
where thunder was left out of the TAFs. 30-40% chance of
SHRA/TSRA at KRDG/KTTN/KABE and 15-25% elsewhere. Winds out of
the southwest 10-15 kt gusting 20- 25 kt. Moderate confidence.

Tonight...VFR with decreasing clouds. Southwest winds gradually
becoming northwest overnight around 5-10 kt following frontal
passage. High confidence.

Friday...VFR. Northwest winds 5-10 kt. High confidence.

Outlook...

Friday night...VFR. No significant weather expected.

Saturday through Sunday...Sub-VFR conditions will be possible
at times in scattered showers and storms.

Sunday night through Tuesday...VFR. No significant weather
expected.

&&

.MARINE...
No marine headlines in place through Friday. Winds out of the
southwest through this evening before becoming northwesterly
overnight. Wind speeds of around 10-20 kt. Seas 3 to 4 feet. A
few thunderstorms possible, especially north of Little Egg
Inlet, this evening.

Outlook...

No marine headlines anticipated. Winds are expected to remain
below 25 kt with seas remaining below 5 ft. Scattered showers
and storms will be possible Saturday and Sunday.

Rip Currents...

For today, southwest winds increase to 15-25 mph with breaking
waves around 1-3 feet and a building southerly 3-4 foot swell
around 6-7 seconds. As a result, have upgraded Cape May and
Atlantic County beaches to MODERATE due to more perpendicular
swell and have maintained a LOW risk for rip currents for the
remainder of the Jersey Shore and Delaware Beaches.

For Friday, northwest winds around 5-10 mph with breaking waves
around 1-2 feet and a southerly 2 foot swell around 6-7 seconds.
As a result, have maintained a LOW risk for rip currents at all
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...Heat Advisory until 8 PM EDT this evening for PAZ060>062-070-
     071-101>106.
NJ...Heat Advisory until 8 PM EDT this evening for NJZ001-007>010-
     012>027.
DE...Heat Advisory until 8 PM EDT this evening for DEZ001>004.
MD...Heat Advisory until 8 PM EDT this evening for MDZ012-015-019-
     020.
MARINE...None.

&&

$$

SYNOPSIS...Cooper
NEAR TERM...Hoeflich
SHORT TERM...Cooper
LONG TERM...Cooper
AVIATION...Cooper/Hoeflich
MARINE...Cooper/Hoeflich