979
FXUS61 KPHI 051051
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
651 AM EDT Sat Jul 5 2025

.SYNOPSIS...
Dry high pressure will will remain in control through the
weekend, resulting in seasonable temperatures and tranquil
weather conditions. Warmer, more humid, and unsettled conditions
will return into next week, with daily chances for showers and
thunderstorms.

&&

.NEAR TERM /THROUGH TONIGHT/...
Large scale subsidence and high pressure will lead to another
day of mostly clear skies and quiet sensible weather for the
region. Highs today will start to warm as southerly flow
increases. The southerly return flow will also start to increase
humidity for the region as dewpoints start to increase from the
upper 50s towards the low 60s. Overall as the previous shifts
mentioned, its going to be a pleasant summer day.

Heading into the overnight hours, temps will fall towards near
normal conditions with lows settling into the mid 60s under
mostly clear to partly cloudy skies. The increase in humidity
continues with dew points remaining in the low 60s overnight so
some patchy ground fog may be possible in areas that see the
winds decouple overnight.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
Dry and seasonable conditions expected to close out the holiday
weekend, then turning unsettled and stormy again with
increasing humidity into early next week.

Broad ridging across the region will begin to retreat offshore
late Sunday into Monday as shortwave troughing develops across
the upper Midwest and Great Lakes regions. At the surface, high
pressure will be located offshore with return flow developing on
Sunday through Monday as tropical cyclone remnants dissipate
across the Carolinas. This setup will result in a slight warming
trend in temperatures, and a more significant increase in
dewpoints and humidity especially by Monday.

For Sunday, high pressure will be located offshore, resulting
in some return flow and thus a more sensible increase in
temperatures and humidity levels compared to the previous days.
Highs Sunday in the upper 80s to low 90s. Lows mostly in the 70
to 75 degree range in most areas as we begin experiencing muggy
nights again. Sunday should be largely dry, however the
diminishing subsidence and increasing influence from the
weakening tropical cyclone over the Carolinas could result in an
isolated thunderstorm across Delmarva.

By Monday, an upper jet streak to our northeast will place our
region in a weak diffluence regime aloft. Thus with the
increasing humidity and diurnally driven instability, we should
experience scattered convection developing by midday. The
convective environment won`t be particularly favorable for
severe thunderstorms, however a few isolated severe storms
cannot be ruled out. Vertical shear is relatively weak, only
around 10-20 kts or so, and the instability profile is tall,
skinny CAPE on the order of 2000 J/kg. PWats will be on the rise
too, perhaps as much as 2.0". So a decidedly tropical
environment with light flow could result in some locally heavy
rainfall amounts and localized flood threat in addition to the
water loaded downdrafts and localized severe threat.

High temperatures Monday will be similar to Sunday in the upper
80s to low 90s, however dewpoints and humidity will be
noticeably higher compared to Sunday. This will result in heat
indices in the mid to upper 90s in most inland areas. Cloud
cover will also be noticeably increased compared to the weekend.
Warm and muggy conditions remaining at night with lows in the
70 to 75 degree range.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
Unsettled conditions expected for the remainder of the upcoming
week. Daily chances of showers and thunderstorms with threats
for localized severe thunderstorms and flooding, along with
very warm and humid conditions.

Southwesterly return flow will continue through Tuesday as a
shortwave trough approaches from the Great lakes region. The
shortwave trough will pass offshore into Wednesday, with another
approaches Thursday or Friday. This should result in the
greatest chances for showers and storms occurring on Tuesday for
the first half of the week, and again Thursday or Friday.

Tuesday`s convective environment will be similar to Monday`s,
although coverage of convection is anticipated to be greater
than Monday given the forcing aloft. PWats in the 2.0-2.3"
range; tall, skinny CAPE on the order of 2000-3000 J/kg; and
relatively low unidirectional shear near 15-20 kts could support
training convection where any surface boundaries are in place.
So again, a marginal severe environment, but perhaps more
concerning is the heavy rainfall and flooding threat this setup
will present. We`ll continue to monitor this potential closely
in the coming days.

Wednesday should see less coverage of convection given the
shortwave trough pushing offshore, but some isolated storms will
certainly remain possible. The next system approaching from the
west by Thursday will then yield greater chances for storms to
close out the week, but details on this remain unclear at the
moment.

Expect temperatures to remain near to slightly above normal
with high humidity levels through much of the week (greatest on
Tuesday). Highs in the mid 80s to low 90s and lows in the mid
60s to mid 70s. Low pressure developing to our west with the
late week shortwave should result in some onshore flow late in
the week, which should tend to moderate temperatures a bit. Heat
indices could approach 100 degrees across the southern half of
the area on Tuesday, however the increased cloud cover and
scattered convection should tend to keep this threat suppressed
some.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Today...VFR. Light and variable wind becoming south-southwest
and increasing to 5-10 kt during the afternoon. High confidence.

Tonight...VFR. Light southwesterly flow. No significant
weather.

Outlook...

Sunday...VFR. No significant weather.

Monday through Wednesday...Prevailing VFR with daily chances
for thunderstorms. Areas of fog possible at night.

&&

.MARINE...
No marine headlines are in effect through tonight. Winds mainly
out of the south-southwest around 5-10 knots through the
period, but may be light and variable at times tonight. Seas of
2-3 feet. Fair weather.

Outlook...

Sunday...No marine hazards expected.

Monday through Wednesday...Daily chances of showers and
thunderstorms, otherwise fair weather.

Rip Currents...

For today, light winds in the morning will become south-
southeasterly around 10 mph in the afternoon. Breaking wave
heights of 1-2 feet with a primary SE swell around 2 feet and a
6-8 second period. This should result in a LOW risk for
dangerous rip currents for all beaches.

For Sunday, southwesterly winds around 5 mph in the morning
will become southerly in the afternoon and increase to 10-15
mph. Breaking wave heights of 1-3 feet with a primary SE swell
around 2 feet and a 6-8 second period. Guidance is hinting at
some longer period swells potentially becoming dominate with
swells ranging from 10-14 seconds. This would increase the Rip
Current risk to at least moderate however given the swells
should be less than 3 feet and breaking waves are small, will
continue a LOW risk for dangerous rip currents for all beaches
at this time.

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...Staarmann
NEAR TERM...Deal
SHORT TERM...Staarmann
LONG TERM...Staarmann
AVIATION...Deal/Staarmann
MARINE...Deal/Staarmann