954
FXUS61 KPHI 200411
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
1211 AM EDT Sun Apr 20 2025

.SYNOPSIS...
Bermuda high pressure will meander off the Mid-Atlantic and
Southeast coasts through the middle of next week. Low pressure
passing north of the region tonight will drag a cold front
through the region. High pressure then builds in from the north
and west Sunday and departs later Monday. Another cold front
passes through the region Monday night. High pressure will be in
control through the middle of the week. A low pressure may
arrive towards the end of the upcoming week.

&&

.NEAR TERM /THROUGH TODAY/...

The MCS that was tracking along the PA/MD border weakened as it
entered our area and is now more along the lines of a gusty
shower. Did increase PoPs to 30% through southern New Jersey as
the remaining precip moves through and eventually offshore in
the next hour or two. Additional slight adjustments were made
to just align with surface observations and satellite imagery.

Previous discussion:

Later tonight the cold front will have crossed the area and
winds will shift to West then Northwest and become gusty for a
few hours. After that, winds will settle to around 10 mph and
clouds will diminish. Low temps tonight will range from the 40s
for the NW areas to the low 60s for SE NJ and Delaware.

Sunday, high pressure builds down from the NW thru the day.
Fair weather is expected with mostly sunny skies. There maybe
some mid level clouds for the afternoon. Breezy and cooler temps
for Sunday with highs reaching the mid/upper 60s for the
northern areas and low 70s for Philadelphia and south NJ. Winds
will be mostly from the North at 10 to 20 mph with gusts up to
30 mph.

&&

.SHORT TERM /TONIGHT THROUGH TUESDAY/...
High pressure will linger to the north Sunday night, with quiet
conditions most likely. However, the weak easterly flow could
produce a some low clouds, mist or drizzle. Lows in the 50s
Delmarva up to Philly metro, 40s further north and east.

Southeasterly flow prevails on Monday as high pressure shifts
east to our north and cold front approaches from the west. This
will keep the region rather cool and may also cause any low
clouds to linger. Highs warmest in the eastern shore of
Maryland, low 70s, 60s rest of the region, except 50s Poconos
and along the coast.

Cold front approaches from the west Monday night, but with the
onshore flow possibly lingering, expect instability to be on the
wane as any convection moves in, while best forcing heads north.
Thus, high end chance POPs north fade to near nothing southern
Delaware. Lows near 60 central Delmarva, 50s most rest of
region, 40s Poconos and possibly the immediate coast.

Cold front passes on Tuesday, helping dislodge the marine layer.
This should allow temps to jump up into the 70s to near 80,
except 60s Poconos and coast. Only meager chance of any showers
with the front itself.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
High pressure slowly builds in from the west Tuesday night, with
partial clearing. Lows 50s I-95 south and east, 40s north and
west.

High pressure continues gradually building east Wednesday, with
warm and dry conditions under some sun. Highs mostly low 70s,
except 60s Poconos and shore.

The high passes near overhead or just north Wednesday night,
with quiet conditions continuing. Lows low 50s to upper 40s.

High shifts just east for Thursday, with some warming under
partial sunshine. Highs mostly mid-upper 70s, except 60s coast.

Next system begins approaching from the west Thursday night, but
only a slight chance of showers currently expected. Lows mostly
50s.

Chance of showers continues to slowly increase Friday on
southwesterly flow ahead of the next system. Still warm, but
clouds and any showers may hold temps back, with highs mainly
mid 70s, 60s Poconos and coast.

Front looks like it stalls in the vicinity with a relatively
high chance of showers Friday night thru Saturday, but just
chance pops still. Lows 50s, highs low 70s.

&&

.AVIATION /04Z SUNDAY THROUGH THURSDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Tonight...Primarily VFR. Some showers/isolated thunderstorms
possible up until midnight from KABE on north. Also cannot rule
out a shower or thunderstorm near KILG/KPHL, but not enough
confidence to include in the TAF. A cold front passing will
result in winds going from southwest to west/northwest, around
10 kt through the night. Until the front comes through between
03z-06z from west to east, expect a period of west/southwest
LLWS 45-50 kt. High confidence.

Sunday... VFR conditions expected with just high clouds across
the area. West northwest winds 10-15 kt, gusting 20-25 kt
through about 18z-19z or so then diminishing. Some guidance
wants to develop a sea-breeze getting to KACY, but modest
northwest flow would prevent one from moving far inland.
Moderate confidence.

Sunday Night...Primarily VFR. Flow turns onshore with
east/northeast winds around 5 kt. With onshore flow developing,
cannot rule out a marine layer working inland, but confidence is
low on if it will develop and if there will be restrictions if
it comes to fruition.

Outlook...
Sunday night through Monday...Sub-VFR possible if persistent
onshore flow causes low clouds or fog/mist/drizzle to develop.

Monday night...sub-VFR possible as passing showers may reduce
cigs and vsby.

Tuesday through Thursday...VFR likely.

&&

.MARINE...
A Small Craft Advisory is in place for all ocean zones through
06z. Seas 4 to 6 feet with occasional gusts near 25 kt. Winds
are lesser on Delaware Bay, with no marine headlines in place

After 06z, sub-SCA conditions expected across all waters with
north/northwest winds 10-20 kt and seas 2 to 4 feet.

Outlook...
Sunday night through Monday...no marine headlines expected.

Monday night into Tuesday...marginal SCA conditions possible
with a passing cold front.

Tuesday night through Thursday...no marine headlines expected.

&&

.FIRE WEATHER...
On Sunday, Min RH values will be 25-30% with northwest winds
10-15 mph with gusts up to 25 mph. This could result in a
Special Weather Statement depending on fuel conditions, but no
statements are currently planned.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 2 AM EDT early this morning for
     ANZ450>455.

&&

$$

SYNOPSIS...OHara/RCM
NEAR TERM...Guzzo/Hoeflich
SHORT TERM...RCM
LONG TERM...RCM
AVIATION...Guzzo/Hoeflich/RCM
MARINE...Hoeflich/OHara/RCM
FIRE WEATHER...