530
FXUS61 KPHI 230102
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
902 PM EDT Thu May 22 2025

.SYNOPSIS...
Low pressure will continue to slide to the northeast and will track
into New England on Friday. At the same time, high pressure will
begin to build into our region on Friday and remain in place through
Monday. Low pressure will move out of the Ohio Valley on Tuesday and
track offshore Wednesday into Thursday.

&&

.NEAR TERM /THROUGH FRIDAY/...
No changes to the previous discussion.

Previous discussion...Primary low pressure will meander over
the eastern Great Lakes before slowly tracking east into central
New York state late tonight and into Friday morning. Meanwhile,
the secondary low east of New Jersey will track north towards
Cape Cod tonight, then both system will merge over Maine Friday
afternoon. A large h5 low will expand much of eastern Canada,
the Great Lakes, the Northeast, and down into the Mid-Atlantic
tonight through Friday, and the center of that low will slowly
track east and will be over northern New England by Friday
afternoon.

In terms of sensible weather, several shortwaves rotating around the
base of the closed low will pass through the region through this
evening. This will touch off occasional showers over the area into
the first part of tonight. There may be enough instability for a
thunderstorm or two over Delmarva early this evening, but not
expecting severe weather.

Showers mostly taper off by midnight tonight, and then there looks
to be a lull in shower activity through Friday morning. Conditions
will be cloudy and muggy tonight, and patchy fog will develop as
well. Lows tonight will be in the 40s to low 50s.

As low pressure intensifies to the northeast, the pressure gradient
will tighten over the area, and northwest winds will increase to
around 15 mph with 20 to 25 mph gusts in the afternoon. Conditions
dry out, and skies may even become partly cloudy for most of the
day. The next shortwave approaches Friday afternoon, touching off
another round of showers, but PoPs will be capped at chance for most
of the area, and as high as likely in the southern Poconos. Highs on
Friday will get into the 60s to around 70.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
The low pressure system responsible for our recent rain will track
into New England on Friday and remain near Newfoundland Saturday and
Sunday. As a result, we`ll only keep a small chance of showers going
across our far NW zones as embedded short waves rotate through this
area. We`ll see a good amount of sun on Saturday across the region,
especially south of the PA Turnpike and 195 in NJ. I feel like a
broken record, but it will be breezy once again on Saturday in the W
to NW flow.

More sun is expected on Sunday with a bit less wind. We could see
more clouds on Monday, especially across our southern zones, but
winds look light right now.

Temperatures will run below normal through the weekend. Highs on
Saturday will mainly be in the 60s, except 50s across the Southern
Poconos and NW NJ. On Sunday, expect 60s to lower 70s. For those of
you heading down the shore, even with surf temps in the upper 50s
right now, you`ll see similar temps compared to inland locales with
the west winds. Overnight lows will mainly be in the 40s.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
The period begins with surface high pressure in play. And it looks
like it will hang around through Monday and very likely into
Tuesday.

As the high breaks down, a low pressure system will move out of the
Ohio Valley on Tuesday and track offshore Wednesday into Thursday.
This will provide the region, especially our southern counties, with
the next widespread shot of rain.

As for temperatures through the period, confidence is high that
they`ll remain at or below normal.

&&

.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Tonight...MVFR/IFR CIGs/VSBYs in occasional SHRA through this
evening, then MVFR/IFR CIGs/VSBYs in BR and stratus for the rest of
the night. E winds around 10 kt, becoming NE this evening, then
becoming LGT/VRB. Low confidence.

Friday...CIGs/VSBYs lift to VFR by 18Z. Scattered afternoon SHRA may
result in brief sub-VFR conditions from 18Z to 00Z, but will not
include i the TAF at this time. W winds 5 to 10 kt increase to 10 to
15 kt with 20 to 25 kt by 18Z. Moderate confidence.

Outlook...

Friday night through Saturday...Mainly VFR. Can`t rule out MVFR
conditions in a brief shower.

Sunday and Monday...Mainly VFR conditions expected.

Tuesday...Mainly VFR early. MVFR or IFR later in the day with rain
moving in.

&&

.MARINE...
Small Craft Advisories remain in effect for the ocean waters through
tonight. Although winds will diminish this evening, seas will remain
elevated. Seas currently average 8 to 11 feet, and seas will
diminish to 3 to 4 feet by daybreak. NE winds 15 to 20 kt with gusts
up to 25 kt will diminish to 10 to 15 kt by this evening, then will
turn W by daybreak. Once the SCA ends, conditions will remain just
below SCA criteria through Friday.

On Friday, W winds will range from 10 to 15 kt with gusts up to 20
kt.

VSBY restrictions in showers through tonight.

Outlook...

Friday night and Saturday...There`s a chance seas could touch 5 ft
or winds gust to 25 kts, but confidence is on the lower side right
now. So not issuing a SCA attm. But at the very least, conditions
will be approaching SCA conditions.

Saturday night through Monday...Sub-SCA conditions expected.

Tuesday...Sub-SCA conditions expected at least the first half the
day. Seas will ramp up later in the day in advance of our next
system. A SCA may be needed later in the day on Tuesday, more so
Tuesday evening.

Rip Currents...

Friday and Saturday...While winds will be offshore coming out of
the west around 10-20 mph, an 8-10 second period, with multiple
swell groups and breaking waves of 2-4 feet will result in a
MODERATE risk for development of rip currents at all beaches.

For specific beach forecasts, visit weather.gov/beach/phi

&&

.TIDES/COASTAL FLOODING...
Coastal Flood Advisories have been allowed to expire. Once we
get to Friday, flow shifts to off shore and thus the risk for
tidal flooding on subsequent high tide cycles decreases for the
ocean and tidal Delaware Bay.

Some guidance suggests some minor flooding within the tidal
Delaware River, particularly on Friday, but confidence was not
high enough to issue further advisories. Higher water levels
could also be a result of freshwater runoff, similar to what
happened last week.

Some spotty minor tidal flooding is possible with the overnight
high tide cycle along the Chesapeake Bay, with the tidal flood
threat decreasing in subsequent high tide cycles.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 6 AM EDT Friday for ANZ450>455.

&&

$$

SYNOPSIS...Kruzdlo
NEAR TERM...MJL/MPS
SHORT TERM...Kruzdlo
LONG TERM...Kruzdlo
AVIATION...Kruzdlo/MJL/MPS
MARINE...Hoeflich/Kruzdlo/MPS
TIDES/COASTAL FLOODING...Fitzsimmons/Hoeflich