592
FXUS61 KPHI 211128
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
628 AM EST Fri Nov 21 2025

.SYNOPSIS...
High pressure will shift offshore through Friday. Developing low
pressure will pass offshore late Friday night followed by high
pressure building into the region through early next week. A strong
frontal system looks to impact the region during the middle to end
of next week.

&&

.NEAR TERM /THROUGH SATURDAY/...
High pressure is weakening and moving offshore early this
morning as a frontal system approaches from the Great Lakes
region. There is also a separate system associated with the
southern branch of the jet that`s over Oklahoma early this
morning but will move eastward towards Tennessee by late day.
It should stay mainly dry through the daylight hours of the day though
skies will generally be overcast. There also could be some
patchy fog around until around mid morning, especially over our
northern and western zones from Berks County northward through
the Lehigh Valley into the Poconos. These areas could also see a
bit of patchy drizzle this morning but confidence is lower on
this. The warm advection pattern will result in warmer highs
for today compared to Thursday with widespread 50s generally
expected except some upper 40s over the Poconos and around 60
over our southern Delmarva zones.

For tonight into Saturday, the polar and subtropical jet will
attempt to phase across the eastern US coast amid modest zonal
flow and broad troughing aloft. Subsidence will then build into
the region in the wake of the trough axis pushing offshore.

A shortwave trough will pass from the Ohio Valley and offshore
from tonight through Saturday, resulting in weak cyclogenesis
east of the Appalachians. This system will bring widespread
light rainfall to the area tonight into Saturday morning,
heaviest along and south of I-78. Rainfall amounts will be less
than impressive, generally ranging from .25 to .50 inches or so
except .10 to .25 inches north of I-78. Lows tonight will be in
the upper 30s and 40s. Highs Saturday ranging from the upper
40s to mid 50s. Skies will start out mostly cloudy to overcast
on Saturday, though there should be some clearing of skies into
the afternoon hours as low pressure moves away. NNW winds
around 10 mph or so for Saturday.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
Cooler and dry high pressure will settle in Saturday night through
Sunday. Lows Saturday night in the mid 20s to mid 30s and highs
Sunday mainly in the upper 40s to low 50s under mainly clear skies.
WSW winds 5-10 mph.

Sunday night will be a bit warmer compared to Saturday night as a
wave passes by to our north resulting in a little more wind and
mixing in the boundary layer. Generally expect lows in the 30s but
it will remain dry.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
Overall seasonable conditions and benign weather expected to begin
next week followed by a warming trend Tuesday into Wednesday as the
next frontal system affects the area. A strong cold front then looks
to move through around Thanksgiving Day but there are some model
differences in the exact timing since this is almost a week out.

In terms of details, the week begins mainly clear for Monday as high
pressure will be centered over the area with seasonable temperatures
(highs mainly in the 50s). Heading into Tuesday, warm advection
strengthens ahead of the next system approaching from the Great
Lakes. This will lead to milder temperatures but also increasing
chances for rain by later in the day and especially at night (POPs
generally around 70 percent).

Heading into the middle to end of next week, differences in the
forecast models increase with regards to how quickly the
aformentioned system moves through. The GFS depicts a secondary
low developing near the triple point Wednesday night into
Thanksgiving Day which would keep periods of rain/shower around
longer but also delay the eventual arrival of much colder air.
Meanwhile the ECMWF and GEM favor a faster progression of the
cold front through the area along with the associated upper
level trough. This would result in drier but much colder weather
building in for Thanksgiving Day. Given this uncertainty we
stayed with the National Blend of models which keeps a 20-30
percent chance of rain going into the first part of Thursday
with highs generally forecast to be in the upper 40s to mid 50s.
It should be noted though that if the system is slower it will
be warmer and wetter (highs Thanksgiving Day in the 50s to low
60s) while if it`s faster it will be colder but dry (highs in
the 30s to low 40s). Regardless of these differences in FROPA
timing around Thanksgiving Day, the trend will be for much
colder air to eventually arrive by next Friday and persist
through Thanksgiving weekend.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Today...MVFR ceilings for most of the day. Improvement to VFR
is possible at all terminals between 19-22Z, though MVFR
ceilings could prevail. Light wind will become southwesterly
around 5 kt. Moderate confidence overall, low confidence in
improvement to VFR.

Tonight...MVFR ceilings for most of the night. Light rain will
move in between 04-08Z. The rain will be steadiest for the I-95
terminals. Visibility restrictions are likely in rain. Ceilings
may drop to IFR, especially during the late overnight hours
towards daybreak Saturday. Light and variable wind with periods
of calm. Moderate confidence overall, low confidence in timing
and extent of IFR restrictions.

Outlook...

Saturday...Sub-VFR early in light rain and low clouds.
Conditions are expected to improve late in the day.

Saturday night through Monday night...VFR. No significant
weather.

Tuesday...VFR to start, with sub-VFR conditions possible later
in the day in periods of light rain.

&&

.MARINE...
Through the day Friday, conditions will remain below advisory
levels, although winds will increase out of the southwest 10-15
knots by late day.

Outlook...

Tonight through Tuesday...No significant weather impacts
anticipated. A period of light rain tonight through early
Saturday, then wind gusts near 20-25 kts possible during the
daytime Saturday. Saturday`s daytime period could have marginal
advisory conditions, but confidence on this is still low.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...None.

&&

$$

SYNOPSIS...Fitzsimmons/Staarmann
NEAR TERM...Fitzsimmons/Robertson
SHORT TERM...Fitzsimmons/Staarmann
LONG TERM...Fitzsimmons
AVIATION...Cooper
MARINE...Fitzsimmons/Robertson/Staarmann