Radnor, Pennsylvania 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

110
FXUS61 KPHI 150518
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
Issued by National Weather Service New York NY
118 AM EDT Thu May 15 2025

.SYNOPSIS...
Low pressure will linger across the Mid Atlantic through today,
resulting in mild, humid, and showery conditions. Brief period
of ridging comes in Thursday Night, with a warm front coming
through on Friday morning. Unsettled weather continues through
Saturday until a strong cold front comes through on Saturday
Night. Drier high pressure will settle into the region by Sunday
into early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Relatively quiet this morning as we are in a bit of a lull in
shower activity. A warm front is trying to move through but is
not making much progress. With weak onshore flow, and a moist
surface, patchy dense fog has developed north of the warm front.
A Dense Fog Advisory is in place through 9 AM for central and
southern NJ and southeastern PA as visibility as low as a
quarter of a mile is expected. Fog will gradually mix out after
sunrise, but could hang around for at least part of the morning
commute.

For today, the low clouds and fog will dissipate as the morning
progresses, and some breaks of sun may even occur by afternoon,
especially across Delmarva. With the mid level trough axis
remaining in the vicinity and the weak surface low nearby as
well, some diurnal instability should result in some isolated to
scattered showers/storms into the afternoon. With PWats around
1.25-1.50", heavy downpours will be possible as well as gusty
winds and small hail. PoPs are generally around 40-50% but those
that see something could see some urban and poor drainage
flooding. A Marginal ERO (1/4) was added to most of the area
given potentially slow storm motion and a saturated surface with
some areas seeing 2-3" yesterday. Severe thunderstorms are
unlikely as shear is pretty weak, but can`t rule it out
completely. High temperatures will be mainly in the 70s and a
bit muggy.

A brief period of quiet weather comes tonight as a brief period
of ridging moves overhead. Skies may actually clear out some
Thursday evening into the first half of Thursday Night before a
warm front moves in late Thursday/early Friday morning. Could
see some patchy fog yet again, though not expecting it to be as
widespread or as dense as this morning. Mainly dry through
Thursday Night though but still mild, with lows in the upper
50s/low 60s.


&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
A warm front lifts through Friday morning, bringing some light
showers as warm air advection ramps up. This will allow temperatures
to climb into the 80s on Friday, with more instability in place as
well. Forcing looks rather weak though with ridging not far away and
only a weak shortwave coming in and no advancing cold front until
Saturday. Thus, thinking it will be just unsettled with scattered to
widespread showers, primarily in the afternoon with a few
thunderstorms mixed in. It`s possible a decaying MCS impacts the
region in the morning sometime Friday, but the severe threat with
this would be low. Showers diminish in coverage with the loss of
daytime heating on Friday Night, but still cannot rule out some
light sprinkles through the night. Mild pattern continues with low
to mid 60s for lows. Saturday looks to be the day to monitor for any
severe weather.

Forcing strengthens with an incoming potent shortwave digging from
the Great Lakes. At the surface, an area of low pressure slides by
to the north Saturday into Saturday Night, with a cold front
advancing towards and eventually through the region. Temperatures
will climb into the 80s and it will feel quite muggy ahead of the
front. Instability looks to be on the order of around 1000 J/kg with
relatively favorable shear. Thinking any showers and thunderstorms
will come in the afternoon and evening as the front arrives. Main
concern would be damaging wind gusts and heavy downpours, but still
a good amount of uncertainty being a few days out. Coverage in
showers and thunderstorms diminishes into the night with the loss of
daytime heating and passage of the front.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Sunday and beyond actually looks pretty nice for now. With the front
coming through, it should result in dry conditions and seasonable
temperatures to close out the weekend and start next week.
Perhaps a little gusty on Sunday, but nothing that looks too
significant.

&&

.AVIATION /05Z THURSDAY THROUGH MONDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Through 12z...IFR/LIFR conditions prevail with potential for
VLIFR in patchy dense fog. VLIFR most likely at KACY/KMIV/KTTN.
A warm front could improve conditions to high-end IFR/low end-
MVFR, mainly at KILG/KRDG, but confidence overall is low. Winds
out of the east around 5 kt or less.

Thursday...IFR and LIFR early. Visibility improvement quickly
through the morning with ceilings scattering out to VFR by
18-21Z. ENE winds 5 kts or less early, shifting southerly around
5-10 kts as conditions improve. Isolated SHRA/TSRA after 18Z.
Low confidence on timing of improvement.

Thursday Night...Most likely VFR to start but restrictions could
return overnight with low clouds and patchy fog. Low confidence.
Winds light and variable.

Outlook...

Conditions expected improve for Friday and Saturday with prevailing
VFR likely during the day, aside from any showers and thunderstorms
move in. VFR conditions look to come Saturday Night and beyond. A
few gusts out of the west/northwest 20-25 kt possible but other
than that, no significant weather beyond Saturday Night.

&&

.MARINE...
A Marine Dense Fog Advisory is in place for all ocean zones and
lower Delaware Bay as 1SM or less visibility has been observed.
The Marine Dense Fog Advisory goes through 9 AM.

A Small Craft Advisory is in effect through 6 AM for ocean zones
south of Great Egg Inlet and until noon for seas around 5 feet.

Some isolated showers/storms possible Thursday afternoon.

No marine headlines expected on Thursday Night.

Outlook...

Sub-SCA conditions expected Friday through Monday. However, showers
and spotty thunderstorms may continue to be a risk through Saturday,
especially during the afternoon and evening hours.

&&

.TIDES/COASTAL FLOODING...
Coastal Flood Advisory is in effect for the upper tidal Delaware
River until 7 AM is minor tidal flooding is expected. Elsewhere,
no additional coastal flooding is anticipated.

Minor coastal flooding is forecast with the overnight high
tides tonight and Friday night as well, especially along the
upper reaches of the tidal Delaware River. Additional advisories
may be needed.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Dense Fog Advisory until 9 AM EDT this morning for PAZ070-071-
     101>106.
     Coastal Flood Advisory until 7 AM EDT this morning for PAZ070-
     071-106.
NJ...Dense Fog Advisory until 9 AM EDT this morning for NJZ012>027.
     Coastal Flood Advisory until 7 AM EDT this morning for
     NJZ017>019.
DE...None.
MD...None.
MARINE...Dense Fog Advisory until 9 AM EDT this morning for ANZ431-
     450>455.
     Small Craft Advisory until noon EDT today for ANZ450>452.
     Small Craft Advisory until 6 AM EDT early this morning for
     ANZ453>455.

&&

$$

SYNOPSIS...Hoeflich/Staarmann
NEAR TERM...Hoeflich/Staarmann
SHORT TERM...Hoeflich/Staarmann
LONG TERM...Hoeflich/Staarmann
AVIATION...Hoeflich/Staarmann
MARINE...Hoeflich/Staarmann
TIDES/COASTAL FLOODING...Hoeflich/Staarmann