Harrington, Delaware 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

514
FXUS61 KPHI 201758
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
158 PM EDT Sun Jul 20 2025

.SYNOPSIS...
In the wake of the cold front moving through the region through
tonight, high pressure builds in over the area through Thursday.
Unsettled weather will return towards the end of the week when
another cold front approaches our region.

&&

.NEAR TERM /THROUGH MONDAY/...
This afternoon, an upper low is located over portions of QC with a
trough axis shifting southeast into portions of far northern New
England. A broad area of surface low pressure is centered over
portions of NH/VT with a cold front trailing it to the southeast.
This cold front will track into the area from the northwest this
afternoon.

Across portions of northern DE, southeastern PA, and southern NJ,
widely scattered showers have developed this afternoon. This
activity could continue into the afternoon. The main hazards with
this activity would be brief heavy rainfall and lightning.

Otherwise, partly cloudy skies have allowed for strong surface
heating across the area, with temperatures having risen into the mid-
upper 80s. Temperatures will likely warm a few more degrees to near
90 as we go into the afternoon. With moist southwesterly flow,
dewpoints have risen into the low-mid 70s.

Despite marginal lapse rates aloft (3-6 km lapse rates are generally
under 6 C/km), strong surface heating has contributed to moderate
instability, with MLCAPE values in the 1500-2000 J/kg range. In
addition, as the trough axis shifts southeast across portions of
New England this afternoon and enhanced mid-level flow overspreads
the area, deep-layer shear will increase to 30-35 kt. The strongest
synoptic-scale forcing for ascent will remain to the north and east
of our area today, but the cold front and subtle forcing aloft is
still expected to be enough to trigger isolated to widely scattered
thunderstorms this afternoon across eastern PA and northern NJ. The
environment in place will support storm organization, with severe
storms being possible. Damaging wind gusts will be the main threat.
In addition, despite somewhat limited storm coverage and fairly
quick storm motions, high tropopause heights and PWATs of 1.5-2
inches will support efficient rainfall production in any storms, and
local flash flooding cannot be ruled out. Due to these threats, the
Storm Prediction Center has placed northeastern PA and northern NJ
in a Slight Risk (2/5) for severe thunderstorms, with a Marginal
Risk (1/5) extending farther southwest towards the Philly metro. The
Weather Prediction Center has placed a Marginal Risk (1/4) for
excessive rainfall across portions of northeastern PA and northern
NJ.

Storm coverage will decrease with southern extent, but at least
isolated convection is possible as far south as the Philly metro and
into portions of southern NJ late this afternoon and early this
evening.

The cold front will clear the area from northwest to southeast by
late evening, ushering in a cooler and much drier airmass. Lows
tonight will range from the mid 60s across eastern PA and northern
NJ to near 70 elsewhere.

High pressure will build in from the northwest as we head into
Monday. There will be a northwesterly breeze, and skies will be
mostly sunny. Highs are expected to generally be in the mid 80s. The
Poconos and areas of far northern NJ could struggle to reach 80. All-
in-all, Monday looks like one of the more pleasant days the region
has seen in the past several weeks.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
This period looks much more pleasant than what we`ve been seeing!
Dry air advection will result in dewpoints in the 50s to lower 60s,
and temperatures will generally top out in the 70s and 80s. Large
surface high and trailing upper level ridge will result in dry
weather.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
By Thursday, the center of the high will be east of the region
resulting in southwesterly return flow. As a result, expect
temperatures and dew points to start increasing once again. At this
point, it looks like Friday will be the muggiest day, with potential
for heat index values near or above 100 degrees for almost all of
the region (with the exception of the Poconos and far NW NJ).

A cold front approaches Friday into Saturday. It may stall out over
the area and linger through the weekend. If that holds true, the
muggy and unsettled conditions could continue through much of the
weekend.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Rest of today...Primarily VFR. Isolated to widely showers and storms
have developed and could impact the terminals this afternoon.
Additional isolated to widely scattered storms could develop across
northern portions of the area in the 21Z time frame and track
generally southeastward. Have high enough confidence to include a
brief temporal window of VCTS for KRDG, KABE, KTTN, KPNE, and KPHL
starting 21-22Z. West-southwest wind 5-10 kt. Should a storm impact
a terminal, strong winds and visibility restrictions could occur.
High confidence in overall pattern, low confidence in
coverage/placement of storms.

Tonight...Primarily VFR. Any storms will clear terminals from
northwest to southeast by 01-02Z. Only some scattered high clouds
will remain overnight. Winds will shift to northwest at 5-10 kt
between 01-03Z. High confidence.

Monday...VFR/SKC. Northwest wind 5-10 kt. A few gusts to 15-20 kt
can`t be ruled out in the afternoon. High confidence.

Outlook...

Monday night through Thursday...VFR conditions expected.

Friday...Prevailing VFR conditions, chances for showers and storms
increase.

&&

.MARINE...
Through Monday...No marine headlines are anticipated. Isolated to
widely scattered storms are possible this afternoon and evening.
Winds will be west-southwesterly today and shift to northwesterly
tonight but will generally remain under 20 kt with seas of 2-3
ft.

Outlook...

Tuesday through Friday...A prolonged period of sub-SCA conditions.
There is the potential for 25 kt wind gusts on the New Jersey
Atlantic waters Thursday.

Rip Currents...

Today, southwest winds will be around 10 mph along with
breaking waves of 1 to 2 feet and a period of 7 to 8 seconds. As
a result, there is a LOW risk for the development of dangerous
and life threatening rip currents at the Jersey Shore and
Delaware Beaches.

On Monday, winds will be out of the north and gradually become
more easterly to even southeast by the evening at 5 to 10 mph.
Breaking waves of 1 to 2 feet and a period of 8 to 9 seconds. As
a result, there is a LOW risk for the development of dangerous
and life threatening rip currents at the Jersey Shore 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...Johnson/MPS
NEAR TERM...Cooper/Franklin
SHORT TERM...Johnson
LONG TERM...Johnson
AVIATION...Cooper/Johnson/MPS
MARINE...Cooper/Johnson/MPS