Radnor, Pennsylvania 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

558
FXUS61 KPHI 150852
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
452 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/...
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 front may 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 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 50-70% for our inland areas. 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 will also remain a threat.

On Thursday, southwesterly flow will bring back warm air and
moisture advection resulting in heat index values approaching
100 degrees in many areas. This could be the warmest day of the
week (unless the cold front on Friday is later than currently
expected).

&&

.LONG TERM /THURSDAY NIGHT 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.

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. Chances for
convection should increase again some for Sunday as the boundary
start lifting north with return flow.

&&

.AVIATION /09Z 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

&&

.HYDROLOGY...
A couple Flood Warnings remain in effect due to ongoing
flooding from Monday`s rainfall. The only River Flood Warning is
up for Chatham along the Passaic River. No additional main stem
river flooding is expected through this morning.

Another round of sporadic heavy rainfall is possible again
today, mainly during the afternoon hours, but will be much less
in coverage compared to Monday. Have considered a Flood Watch
across our southern Delmarva counties, but have opted to hold
off on this as uncertainty lies with how much convection
actually does develop.

&&

.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/RCM/Staarmann
MARINE...DeSilva/Johnson/RCM/Staarmann
HYDROLOGY...PHI