128
FXUS61 KPHI 051922
AFDPHI

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

.SYNOPSIS...
A surface high will progress northeastward away from the region
through tonight as a low pressure system lifts off the coast of
the Carolinas and out to sea. The next cold front is expected
to cross our region Sunday evening into Sunday night. In the
wake of that front, high pressure builds in for the first half
of the work 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 MONDAY/...
A subtle mid-level impulse will pass through the region
Saturday night. The region will remain within large scale
troughing through Monday, with a strong shortwave passing to the
north Sunday night into Monday morning. At the surface, low
pressure will pass to our north over New England, with the
associated cold front passing through the area on Sunday evening
into Sunday night. High pressure will build in thereafter.

Partly to mostly cloudy skies to start Saturday night should
give way to mostly clear skies. With light winds, strong
radiational cooling is anticipated. Lows should be in the low to
mid 20s outside of the urban corridor and for the coastal
plain, where upper 20s to near 30 can be expected.

Cloud cover will increase on Sunday with the approach of the
cold front. It should be mostly dry, though there may be enough
moisture for a few light snow showers to occur Sunday evening
into Sunday night with the frontal passage, mainly north of
I-78. For right now, PoPs are limited to around 20%. Highs on
Sunday look to be in the mid 30s northwest of the fall line and
low-mid 40s elsewhere. Sunday night, clouds should decrease
behind the front, though breezy northwest winds will commence
with gusts 20-25 mph possible. Lows look to be in the upper
teens across the higher elevations on eastern PA and far
northern NJ and the mid 20s elsewhere. Wind chill values could
fall into the single digits for the Poconos, and teens for most
of the area.

Monday should be partly cloudy and dry, with a breezy northwest
wind continuing. With highs only in the 20s and 30s, it will
remain quite cold areawide, with wind chills remaining in the
teens and 20s.

&&

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

In the wake of the cold front, temperatures Monday Night will
be 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 mostly clear skies 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, especially across northwestern portions of the area,
which could limit or cut short the radiational cooling. Should
the forecast trend colder, northern portions of the forecast
area could approach Cold Weather Advisory criteria. High
temperatures Wednesday look to remain several degrees below
average.

Beginning Tuesday night, A potent shortwave will dig
southeastward across the Northern Plains and into the Great
Lakes region. It will pivot through the region on Wednesday.
With a larger scale eastern trough settling into the region for
Thursday into Friday. There is strong model agreement in a
surface low tracking out of Great Lakes and into southern
portions of Quebec or northern New England Wednesday night, with
a trailing cold front tracking through the area by Thursday
morning.

As of right now, it appears that precipitation chances will
begin to increase Wednesday afternoon, peaking Wednesday night,
with PoPs generally 30-60%. Temperatures will be moderating
during this period to near or just slightly below normal, so
rain is the most likely precipitation type for most. With that
said, some wintry precipitation could occur, especially from the
southern Poconos into far northwestern NJ. The frontal passage
will usher below average temperatures back in to the area.

Both the deterministic GFS and ECM feature another storm system
that could impact the area on Friday. Ensembles feature lowered
surface pressure but with a significant spread on potential low
placement. For now, the NBM features slight chance (around 20%)
PoPs areawide Thursday night and Friday, which seems reasonable
given the range and model discrepancies.

&&

.AVIATION /19Z 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 Sunday...VFR. No significant weather.

Sunday night...Primarily VFR. Slight chance for a few snow
showers (around 20%) for KRDG and KABE.

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

Wednesday...Sub-VFR conditions will be possible with a chance
(20- 40%) of rain.

&&

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

Outlook...

Saturday night through Sunday...No marine headlines anticipated
with winds below 25 kt and seas below 5 feet.

Sunday night through Monday night...SCA conditions expected
beginning late Sunday night and continuing into Monday with
northwest winds increasing to 20-30 kt. There will be a 20-30%
chance of gales. Seas 4-6 feet. Winds and seas diminishing by
daybreak Tuesday.

Tuesday...SCA conditions possible with with south winds
increasing to 15-25 kt. Seas 3-5 feet.

Tuesday night through Wednesday... SCA conditions expected with
gales possible. South winds increasing to 20-30 kt. Seas 4-7
feet.

&&

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