354
FXUS61 KPHI 051739
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
1239 PM EST Fri Dec 5 2025

.SYNOPSIS...
High pressure will shift offshore into tonight. Meanwhile, a
low pressure system will be lifting off the coast of the
Carolinas and further out to sea. The next cold front is
expected to cross our region Sunday into Sunday night. In the
wake of that front, high pressure builds in for the first half
of the week, followed by another low pressure system approaching
our region Wednesday into Thursday.

&&

.NEAR TERM /THROUGH SATURDAY/...
Some freezing drizzle possible tonight, especially along and
south/east of the I-95 corridor and inland from the immediate coast.

Our region will remain on the southeastern periphery of a large
upper-level trough/closed low in central to portions of eastern
Canada. A surface low well to our south will continue to shift
eastward and out to sea tonight. This low resulted in light snow
accumulations today across Delmarva and far southern New Jersey.
This light snow event is gradually winding down this afternoon.

As the aforementioned surface low shifts away from the lower Mid-
Atlantic coast tonight, lingering precipitation is expected to
continue to dissipate. However, weak flow in the lowest levels of
the atmosphere combined with some warming aloft will result in a
strengthening low-level inversion. This will trap in the low-level
moisture and may act to squeeze some of it out. While this is
occurring, notable drying is forecast above the inversion as seen in
forecast model soundings. This points to more of a drizzle setup.
Some of the guidance shows a weak low-level convergence zone or
inverted surface across parts of our area and this could help to
provide a bit more lift. If this were to occur, then perhaps some
flurries or light snow is able to be generated especially if the
saturated layer is cold/deep enough. This is a challenging forecast
especially when it comes to any impacts. Air temperatures and also
surface temperatures will be cold tonight (although cloud cover may
slow the temperature drop tonight especially in Delmarva to
southeastern New Jersey where dew points are higher). Some spotty
light icing cannot be ruled out where any freezing drizzle occurs.
Held PoPs no higher than the chance range and held off on any
headline products due to low confidence. The low-level moisture may
also result in some fog, although visibility restrictions may be
more tied to any light precipitation.

As we go through the day Saturday, the synoptic setup remains similar
as tonight with the exception of a weak trough axis getting closer
to our area from the west. The low-level flow therefore turns more
out of the west and results in somewhat milder air arriving. It will
remain below average however. Moisture trapped below an inversion
should result in low clouds to start the day, which then lift
through the day as additional drying is able to mix into the
boundary layer. Clouds however look to dominate much of the area
however. Cannot rule out some flurries or freezing drizzle for a
time in the morning, however this should be spotty but confidence
remains low on the occurrence/extent of it.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
The big story in the short term will be the cold front crossing
through our region late Sunday into Sunday Night.

With the main trough axis to our northwest Saturday night and
Sunday, surface winds will shift to southwesterly allowing a
brief warming trend. Temperatures will be about 5 to 10 degrees
below normal for this time of year, but this will be about 10
degrees warmer than temperatures today.

As we go through Sunday, an upper-level trough across much of
eastern Canada amplifies southward. The associated cold front is
expected to cross our region late Sunday into Sunday night.
Despite the weak southerly/southwesterly return flow Saturday
into Sunday, moisture will likely be limited. There is a 20 to
30% chance for light snow with the frontal passage, primarily
across East Central PA and northern NJ.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
The two key messages in the long term are the potential for much
colder than normal temperatures Monday into Tuesday, and the
next low pressure system approaching our region Wednesday into
Thursday.

In the wake of the cold front, temperatures, especially Monday
and Monday Night, will be well below normal, as much as 20
degrees below normal. For now, have stayed pretty close to the
blend of models. However, there are some factors suggesting that
guidance could have a warm bias on Monday night/Tuesday morning.
During that time, the surface high will be very close to our
region, with clear skies (at least to start the night) and very
light winds. These types of efficient radiational cooling
patterns tend to end up colder than the median blend of
guidance. However, some guidance suggests that clouds could
start to build in as early as the pre-dawn hours on Tuesday
Morning, which could limit or cut short the radiational
cooling. While it doesn`t look like we will be getting close to
any record lows, in some areas our current forecast is only 5 to
10 degrees away from Cold Weather Advisory criteria.

For Wednesday and Thursday...The eastern Canadian upper-level low
looks to reposition itself as an additional shortwave trough
digs southeastward on its western and southern flank. This
would tend to support low pressure at the surface in the Midwest
and Great Lakes Wednesday which then moves our way into
Thursday. There remains uncertainty with this given all the
moving pieces within the parent upper-level trough, therefore
did not deviate from the blend of guidance. PoPs, especially
with the Wednesday night period are higher with the latest
guidance as compared to yesterday, but there remains
considerable uncertainty. While some moderation in the
temperatures are forecast ahead of this feature, below average
values are expected to continue.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

This afternoon...VFR or MVFR ceilings lower to MVFR. Some lingering
light snow from KILG to KMIV and near KACY with MVFR/IFR
visibilities for a time. East-northeast winds 5-8 knots becoming
east-southeast. Low confidence.

Tonight...MVFR ceilings lower to IFR. Some drizzle/freezing drizzle
or very light snow possible especially for the I-95 corridor
terminals and KMIV/KACY. Winds light and variable to calm. Low
confidence, therefore no precipitation included in the TAFs at
this time.

Saturday...IFR/MVFR ceilings improve to VFR by early afternoon.
Light and variable winds becoming westerly around 5 knots. Low
confidence.

Outlook...

Saturday Night through Tuesday...Prevailing VFR.

&&

.MARINE...
Winds are expected to remain on the lighter side and seas below 5
feet through Saturday, therefore no marine headlines.

Outlook...

Saturday night and Sunday...Winds and seas will stay below SCA
criteria.

Sunday Night through Monday...SCA conditions are expected and gale
conditions are possible behind a cold front Sunday Night that will
also bring an abrupt shift to northwesterly winds. There is a 20 to
40% chance that gale force conditions will develop in this period.

Tuesday...Late Tuesday, wind gusts near or above 20 kt are expected,
but we are currently forecasting winds to stay below SCA criteria.

&&

.TIDES/COASTAL FLOODING...
As a result of the Full Moon on December 4th, some minor tidal
flooding will be possible during the daytime high tides through
Sunday. This is primarily for the NJ and DE coasts and lower
Delaware Bay. It does appear that tidal departures will
increase slightly Saturday into Sunday, increasing the chance
for minor tidal flooding especially for the southern New Jersey
and Delaware coasts, including parts of the lower Delaware Bay.

No tidal flooding is expected elsewhere.

&&

.CLIMATE...
Very cold Monday Night into Tuesday Morning. At this point, we
aren`t forecasting to break any record lows. Below are the
record lows for December 9.

SITERECORD/YEAR
Allentown (ABE)      7/2002
AC Airport (ACY)     6/1968
AC Marina (55N)      5/1876
Philadelphia (PHL)   6/1876
Wilmington (ILG)    13/1960
Reading (RDG)        0/1989
Trenton (TTN)       12/2002
Mount Pocono (MPO)  -1/1902
Georgetown (GED)    10/1976

&&

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

&&

$$

SYNOPSIS...Johnson
NEAR TERM...Gorse
SHORT TERM...Gorse/Johnson
LONG TERM...Gorse/Johnson
AVIATION...Gorse/Johnson
MARINE...Gorse/Johnson
TIDES/COASTAL FLOODING...PHI
CLIMATE...PHI