086
FXUS61 KPHI 041126
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
626 AM EST Thu Dec 4 2025

.SYNOPSIS...
An arctic cold front will cross through the area this afternoon.
Arctic high pressure builds in late tonight into Friday before
shifting offshore by Friday night. An area of low pressure tracks to
our southeast Friday night with weak high pressure filling in over
the weekend. Another cold front passes through late Sunday. High
pressure returns for Monday and Tuesday, followed by another low
pressure system toward the middle of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
For today, a cold front will pass through the region, ushering in
an arctic airmass. While the frontal passage will mainly be dry for
most, there may be just enough moisture, lift, and instability to
result in a few snow showers along and north of I-80 during the day.
While this should generally be not impactful, the snow squall
parameter is not zero, so a few squalls reaching the far northern
part of our area cannot be ruled out. Otherwise for most, the main
impact will be increasing winds as the front passes and in its wake
as strong cold-air advection ramps up. Winds increase with gusts
around 25-35 MPH expected out of the northwest. Temperatures will
be in the mid to upper 30s and low 40s Thursday, but it will
certainly feel cooler than that with a brisk northwesterly wind.

Behind the front, temperatures will take quite the tumble Thursday
night with lows falling into the teens and low-20s for much of the
region with single digits across the Poconos and high elevations of
northwestern NJ. There will be a wind chill factor as well, however
this will be mostly during the evening as the winds are expected to
mostly decouple during the night, limiting how low wind chills will
get. Some record low temperatures could be challenged for December
5th, especially in the Lehigh Valley and Berks County. Record low
temperatures are listed below in the climate section for reference.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
The center of the Arctic high will be located over the lower Hudson
Valley on Friday morning and will quickly shift east of Cape Cod
later in the afternoon. An impulse aloft will also be arriving later
in the day and into Friday night. As it does so, surface low
pressure is forecast to develop near Hatteras and track east-
northeast into the western Atlantic. For now, no real changes have
been made to the forecast, as the onset of precipitation will likely
begin as a period of light snow near daybreak on Friday as
temperatures will be below freezing. However, as temperatures warm
throughout the course of the day, expect a gradual changeover to a
mix/plain rain for areas along the immediate coast where highs will
rise into the mid to upper 30s. Inland locales however, will likely
remain snow as temperatures will remain near or below freezing. The
highest PoPs still remain located across the Delmarva and far
southern NJ which will be in closer proximity to the developing
surface low. One thing to note however, is that with such a dry,
albeit cold airmass in place ahead of the low, it is likely that
there`ll be a sharp cut-off on the northern edge of the
precipitation shield. Most guidance insists that the northern edge
of the precipitation shield will be near (or just north of) the I-95
corridor, where some guidance such as the (ECMWF) continues to
extend the precipitation shield as far north as the southern
Poconos. As a result, have opted to trim back accumulations on the
northern edge of the system keeping most snow accumulations along
and southeast of I-95. Regardless, many areas that did not see
accumulation snow earlier in the week, may see their first
accumulating snowfall of the season. Accumulations up to one inch is
possible; greatest totals over the Delmarva region.

By Friday night, the low will quickly depart and move into the
western Atlantic causing most precipitation to cease. However, some
isolated areas of light snow or rain may linger into Friday night,
especially for areas near the coast. In fact, BUFKIT soundings show
a subtle warm-nose around 925 mb across portions of the area. This
could result in isolated pockets of light freezing rain or freezing
drizzle as low-level moisture lingers. For now, have left out any
ice accumulation, but will need to monitor this potential with
future forecast cycles.

Broad high pressure returns on Saturday under a mix of partly to
mostly cloudy skies. Temperatures will rebound a bit but will still
remain below normal as highs range from mid 30s to mid 40s with lows
primarily in the 20s.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Synoptic Overview...An upper-level trough is forecast to be across
much of eastern Canada Sunday and Monday. This feature looks to
extend south across much of the Eastern U.S. especially as stronger
shortwave energy transverses along the southern parts of the trough
into the Southeast U.S. The trough may weaken Tuesday into
Wednesday, however this will depend on if a stronger shortwave dives
out of the Midwest Monday night and Tuesday. At the surface, a cold
front arrives late Sunday with high pressure sliding across our area
Monday into Tuesday. Another area of low pressure then looks to
arrive toward the middle part of the week with its associated fronts.

For Sunday and Monday...An upper-level trough across much of eastern
Canada amplifies southward as shortwave energy rounds its base
across the southern states. As this occurs, a cold front looks to
cross our area late on Sunday. The moisture associated with this
front looks to be quite limited, so outside a stray rain or snow
shower, much of the region looks to remain dry. However, this front
will deliver another shot of reinforcing cold air. Temperatures are
forecast to remain below average, with it being much colder on
Monday compared to Sunday. As the axis of high pressure moves across
our area Monday night, temperatures are forecast to be very cold
with lows in the teens (single digits across the far north). For
now, winds do appear to be rather light, so no cold weather
headlines look to be warranted.

For Tuesday and Wednesday...Despite the main upper-level trough
looking like it may flatten toward the middle of the week, a
potentially strong shortwave diving out of the Midwest may end up
crossing through our area. This feature may support a clipper-type
system at the surface, which quickly crosses our area Tuesday night.
The moisture is typically limited with these features, however if
the mid-level wave is stronger like some guidance suggests then
forcing for ascent would be stronger. There is uncertainty with this
given all the moving pieces within the parent upper-level trough,
therefore did not deviate from NBM guidance which essentially
carries a 20-30% chance of light snow across the northern half of
the forecast area. Cold/below average temperatures are expected to
continue through the middle of the week regardless of the upper
pattern.

&&

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

Thursday...VFR. Winds increasing with a frontal passage between
14z- 16z. West/northwest winds 10-20 kt with gusts around 25
kt. High confidence in prevailing VFR, moderate confidence in
timing of frontal passage and winds increasing.

Thursday night...VFR. West-northwest winds around 15 kts diminishing
below 10 kts late. High confidence.

Outlook...

Friday through Friday night...Sub-VFR conditions possible with
periods of light snow and light rain. Greatest probabilities is
along the I-95 corridor terminals south and east.

Saturday through Monday...Primarily VFR. Outside of a slight chance
of a shower on Saturday, no significant weather is expected.

&&

.MARINE...
A Small Craft Advisory goes into effect for all marine zones
beginning at 14z. West/northwest winds around 15-25 kt with gusts
around 30 kt expected. Seas 3 to 5 feet. SCA conditions decrease
through the evening and overnight hours.

Outlook...

Friday through Sunday...No marine headlines expected.

Sunday night through Monday...SCA conditions possible with wind
gusts around 25 kt and seas building up to 6 feet.

&&

.TIDES/COASTAL FLOODING...
As a result of the Full Moon phase occuring today, December 4th,
areas of spotty minor tidal flooding are possible with upcoming
high tide cycles. More prominently, this morning`s high tide
cycle along the southern New Jersey and Delaware coasts,
including parts of the lower Delaware Bay, may observe areas of
spotty minor flooding. Additional spotty minor tidal flooding
may be observed with Friday and Saturday morning`s high tide
cycle, but generally expect all gauges to remain below advisory
criteria.

No other tidal flooding is expected elsewhere.

&&

.CLIMATE...
Very cold temperatures are forecast for early Friday morning which
may challenge a few record lows.

Record Low Temperatures for December 5th...

SITERECORD/YEAR
Allentown (ABE)11/1926
AC Airport (ACY)11/1966
AC Marina (55N)15/1901
Philadelphia (PHL) 13/1886
Wilmington (ILG) 12/1926
Reading (RDG) 12/1926
Trenton (TTN) 10/1926
Mount Pocono (MPO) -2/1971
Georgetown (GED) 14/1966

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 10 PM EST this evening for ANZ430-
     431.
     Small Craft Advisory until midnight EST tonight for ANZ450>455.

&&

$$

SYNOPSIS...DeSilva/Gorse
NEAR TERM...MJL
SHORT TERM...DeSilva/Gorse
LONG TERM...DeSilva/Gorse
AVIATION...DeSilva/MJL
MARINE...DeSilva/MJL
TIDES/COASTAL FLOODING...
CLIMATE...