428
FXUS61 KPHI 030224
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
924 PM EST Tue Dec 2 2025

.SYNOPSIS...
Low pressure continues to move offshore overnight. Following it, high
pressure gradually builds in from the southwest late tonight and
Wednesday. A strong cold front crosses our area during Thursday,
followed by high pressure later Thursday night into Friday. An
area of low pressure is currently forecast to track just to our
south an east later Friday into Saturday, followed by a cold front
later Sunday.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
Widespread precipitation has ended across our region. Clouds
remain across many areas, but a large clearing area across metro
Philadelphia and south NJ is noteworthy. It appears that this
will fill in the next few hours. Clouds will prevail early
tonight, but then more clearing arrives by dawn. Clouds will
hold fast N/W the longest. Winds have increased this evening
from the Northwest bringing in the dry air. Gusts 20 to 25 mph
expected during the overnight.

Lows tonight will drop into the 20s for most, which may lead to
some black ice issues where any slushy snow melt refreezes on
roadways (especially north of I-78).

A high pressure system remains in control for Wednesday with dry
conditions. It will be a colder day with highs in the mid 30s to
mid 40s. A breezy wind out of the northwest in the morning at 15-20
mph will lessen through the day.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/...
Following a subtle upper-level ridge axis, enhanced southwesterly
flow aloft will begin to overspread the area into Thursday as a
trough digs southeastward over portions of Ontario and eventually
Quebec. The trough axis will pass to the north/glance the region
Thursday. Subtle height rises will follow with the flow aloft
becoming more zonal Thursday night. At the surface, high pressure
will build in from the west on Wednesday. A surface low will pass
well to the north of the area on Thursday, however a strong trailing
cold front moves through Thursday. Wednesday night will feature
increasing clouds from northwest to southeast as the cold front
begins to approach the region. Lows will be mostly in the 20s.

Thursday will feature more clouds ahead of and with a strong cold
front. Moisture looks to be rather limited with this cold front and
the main lift also slides by to our north. There is some chance
though, low, that a few snow showers occur with the front across
mostly the Poconos. A west-northwest wind increases and turns gusty
(gusts up to 30 mph) during the day Thursday before diminishing at
night. The notable breeze will add to the chill factor. Highs
generally in the 30s northwest of I-95 and 40s to the southeast. As
the winds diminish Thursday night, temperatures look to bottom out
in the teens for many areas with even some single digits in parts of
the Poconos.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Synoptic Overview...An initial zonal flow aloft gives way to a
shortwave trough crossing our area later Friday into Saturday.
The flow aloft may then undergo amplification across the East
later in the weekend into early next week. At the surface, high
pressure departs to start Friday then low pressure develops and
slides to our south before it shifts farther offshore into
Saturday. A cold front arrives then later Sunday with weak high
pressure nearby Monday into Tuesday.

For Friday and Saturday...High pressure is centered over our area to
start within an initial zonal flow aloft. A shortwave trough however
looks to quickly arrive later in the day Friday and especially
Friday night. This feature does not appear to sharpen much as it
arrives given the more zonal flow aloft ahead of it, although this
could change if additional energy can phase with it. A cold and very
dry air mass is forecast to be in place, and this may hinder the
northward placement of a precipitation shield. Surface low pressure
is forecast to develop and track to our south as a result and tend
to be a quick mover. Given the current synoptic setup, the highest
probability of precipitation is across the southern to eastern areas
(Delmarva to southeastern New Jersey). Some snow or even a wintry
mix is possible across these areas with even some change to rain,
with snow then as the main precipitation type farther north.
Something to watch however is whether a zone of frontogenesis or
strengthening frontogenesis occurs resulting in a banding feature
north to northwest of the surface low. This would tend to occur if
the mid level wave sharpens more than currently forecast. The
details will be determined by the track and strength of the system
which will then determine the precipitation types and amounts. Given
the uncertainty with these (finer) details no major changes were
made to the National Blend of Model (NBM) guidance. Rather cold
Friday with high ranging from mid to upper 20s far north to upper
30s far south. It turns milder then Saturday in the wake of the
system, however still below average.

For Sunday through Tuesday...An upper-level trough across eastern
Canada may undergo amplification south and eastward through about
Monday before weakening occurs. Another piece of energy dropping
down into the Mid-Mississippi Valley may then sharpen the trough
eastward again Tuesday with surface low pressure potentially
approaching our area during Tuesday. Quite a bit of uncertainty with
the evolution of the features within the larger scale trough,
therefore just some slight chance PoPs (20 percent) in the forecast
as of now at times Sunday night through Tuesday. Temperatures
currently are forecast to be on the cold side, especially early next
week.

&&

.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.


Tonight...Conditions will improve overnight as clouds decease.
Most areas MVFR attm, but will become VFR 06Z-09Z. Northwest
winds 10-15 knots with gusts 20-25 knots. High/medium confidence.

Wednesday...VFR conditions expected. Northwest winds around 10 knots.
High confidence.

Outlook...

Wednesday night...VFR.

Thursday...VFR. West-northwest wind gusts 20-25 knots during the
day, then diminishing at night.

Friday and Saturday...A period of sub-VFR conditions possible along
with some rain/snow (highest probability currently south and east of
KPHL).

Sunday...Mostly VFR.

&&

.MARINE...
Winds and seas will continue to increase this afternoon. Winds
will gust to 25-30 knots and turn to be out of the north to
northwest by this evening. Occasional gusts to 35 knots are
possible on the ocean zones tonight. Seas will reach 3-6 feet
tonight as well. As a result, a Small Craft Advisory is in
effect for the Atlantic Ocean coastal waters already and starts at
3 PM for the Delaware Bay. The SCA will continue through
tonight for all coastal waters.

For Wednesday, the Small Craft Advisory on the Delaware Bay will
end at 6 AM while the Atlantic Ocean coastal waters go through
1 PM. Winds and seas will continue to lessen through the day
Wednesday.

Outlook...

Wednesday night...The conditions are anticipated to be below Small
Craft Advisory criteria.

Thursday...Small Craft Advisory conditions probable.

Friday through Sunday...The conditions are anticipated to be below
Small Craft Advisory criteria.

&&

.CLIMATE...
Widespread moderate to heavy precipitation is expected today.
A few daily precipitation records could be challenged. Records
for our climate sites are listed below:

Record Precipitation (Rainfall)
                       December 2
Site                  Record/Year
Allentown (ABE)        0.86"/1934
AC Airport (ACY)       1.03"/1996
AC Marina (55N)        1.18"/1929
Georgetown (GED)       1.11"/1974
Mount Pocono (MPO)     3.56"/1996
Philadelphia (PHL)     1.48"/1986
Reading (RDG)          1.29"/1981
Trenton (TTN)          2.13"/1986
Wilmington (ILG)       1.27"/1991

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 6 AM EST Wednesday for ANZ430-431.
     Small Craft Advisory until 1 PM EST Wednesday for ANZ450>455.

&&

$$

SYNOPSIS...Gorse
NEAR TERM...Guzzo/po
SHORT TERM...Gorse/MJL
LONG TERM...Gorse
AVIATION...Gorse/Robertson/po
MARINE...Gorse/Guzzo
CLIMATE...