063
FXUS61 KPHI 071411
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
911 AM EST Sun Dec 7 2025

.SYNOPSIS...
Weak high pressure moves offshore today before dissipating. A cold
front will cross through the area tonight, followed by Arctic high
pressure which will build across the Great Lakes and dominate
through Tuesday. An area of low pressure will impact the region on
Wednesday with its associated fronts. Brief high pressure returns on
Thursday, followed by a clipper system Thursday night into Friday.
High pressure should then return by next weekend.

&&

.NEAR TERM /THROUGH MONDAY/...
Areas of freezing fog across the Delmarva are dissipating, so
the Freezing Fog Advisory has been allowed to expire as
scheduled. Caution is still advised if traveling over the next
few hours as temperatures remain below freezing and there could
be some lingering slick spots.

Our attention now turns to the cold front moving in tonight
into Monday morning. It still appears that the front itself will
be mostly dry for our area (though can`t rule out a few
flurries, especially for the southern Poconos). The main impacts
will be the dramatic temperature difference and wind changes.
Guidance tends to have a low bias with arctic cold air advection
regimes even if the trough isn`t very amplified (as this one
doesn`t appear to be), so have included wind speeds and gusts on
the higher end of guidance. Even so, should stay well below
wind advisory thresholds. The peak gusts in our region will
likely be in the 35 to 40 mph range.

Temperatures on Monday are expected to be 5 to 10 degrees lower
than Sunday, with highs only ranging from the lower 20s to mid
30s. Wind chill values are expected to be in the teens and 20s.

Also of note on Monday, one of the high res models - the HRRR -
depicted the low forming off the southeastern US coast on
Monday considerably further north that other models. If this
were to verify, it would mean that snow (albeit light in our
area) would be possible as far north as South Jersey. For now,
this appears to be an outlier, so have stayed close to the blend
of guidance.

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
The short term period as a whole is highlighted by a blast of very
cold temperatures (as much as 10-20 degrees below normal). Large and
expansive Arctic high pressure will exit the Great Lakes region and
settle overhead for Monday night. This high will shift east off the
coast of New England on Tuesday with southerly return flow returning
late in the day into Tuesday night.

Monday night will by far be the coldest night of the week and likely
so far this season for most locales. With the high essentially
settling directly overhead, light northerly winds should become calm
at times, and with clear skies, this should equate to optimal
conditions for radiational cooling. Low temperatures ranging from
the single digits to upper teens appear likely. Considering the set-
up in place, considered blending in some colder guidance, which
would result in temperatures below zero in some spots. As of now,
cold weather headlines do not appear to be warranted, however.

For Tuesday and Tuesday night, high pressure departs but will still
largely be in control with dry weather conditions. Return flow will
shift to more southerly, allowing temperatures to moderate some, yet
remain well below normal. Skies will be mostly clear to start the
day, but an increase and thickening of clouds are expected come
Tuesday night. High temperatures in the low 30s to low 40s are
expected with lows in the low 20s to low 30s for most of the area.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
The long term pattern then becomes more active across the Eastern US
with several areas of low pressure and their associated fronts
taking aim at the area. Guidance has come into better agreement with
Wednesday`s system as a rather strong shortwave tracks through the
Great Lakes with an upper level low meandering within the vicinity
of the Hudson Bay. At the surface, low pressure will track out of
the Great Lakes and across southern Quebec into Wednesday night. As
it does so, its associated cold front will cross through the Mid-
Atlantic region. This will be the next opportunity for much of the
area to recieve some kind of precipitation. With the region located
well south of the low center, so its likely that this precipitation
will be mostly in the form of rain...although some snow cannot be
ruled out in the Poconos. Temperatures for Wednesday will be close
to average. Following the frontal passage, temperatures are expected
to dip back below average for Thursday as some weak ridging at the
surface returns. Aloft, the Mid-Atlantic will remain nestled well
under the deep trough, yielding the continuation of cool weather.

Beyond Thursday and continuing into next weekend, guidance diverges
significantly with the timing, position and strength of features. As
of now, it does appear that will be some sort of `clipper-like`
system that will move into the region Thursday night into Friday.
This system looks to be a rather quick mover, but temperatures will
be cool thanks to the frontal passage the day prior. This could
result in a period for light snow and/or light rain across the area,
but ultimately comes down to timing and the track of the low. For
this reason, kept NBM guidance which depicts a 30-50% chance of
light rain/snow across much of the area. Behind this system though,
will be another period of dry weather but very cold temperatures for
next weekend. Early indications are for daytime highs to struggle to
reach the freezing mark at times.

&&

.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Today...Any lingering fog should dissipate by 14Z. Thereafter,
VFR conditions expected, though a ceiling around 3500 ft AGL may
linger through the morning at KABE and KRDG. Southwesterly wind
around 5 kt. High confidence.

Tonight...VFR expected. Between 03 and 09Z, expect an abrupt
shift to northwesterly winds with wind speeds increasing to
10g20kt.

Outlook...

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

Wednesday through Wednesday night...Sub-VFR conditions possible at
times. A chance for rain at all terminals, with a slight chance of
snow at KRDG and KABE. Wind gusts in excess of 20 kt possible.

Thursday...VFR. A slight chance of rain, otherwise no significant
weather expected.

&&

.MARINE...
Winds and seas will stay below Small Craft Advisory conditions
today into this evening.

Late tonight into early Monday Morning, a cold front will cross
over the waters, bringing an abrupt shift from southwesterly to
northwesterly winds. Wind speeds will also increase quickly
behind this front. Wind gusts near or above 30 kt are forecast.
A Small Craft Advisory is in effect for the Atlantic Coastal
Waters and the Delaware Bay starting Late Tonight and continuing
through the day time on Monday. Winds are expected to slowly
begin to subside Monday Afternoon, but it may take time for the
seas to subside.

Outlook...

Monday night...Lingering SCA conditions likely with wind gusts
up to 20-25 kt and seas around 3-6 feet.

Tuesday...No marine headlines expected.

Tuesday night through Thursday...SCA conditions likely with a brief
period of gales possible on Wednesday. Seas may build in excess of 8
feet.

&&

.TIDES/COASTAL FLOODING...
Now several days removed from the Full Moon phase that occurred
on December 4th, expect one more round of spotty minor tidal
flooding with this morning`s high tide cycle. This is primarily
for the NJ and DE coasts and 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...Small Craft Advisory from 1 AM to 6 PM EST Monday for ANZ430-
     431-450>455.

&&

$$

SYNOPSIS...DeSilva
NEAR TERM...Cooper/Johnson
SHORT TERM...DeSilva/Staarmann
LONG TERM...DeSilva/Staarmann
AVIATION...DeSilva/Johnson
MARINE...DeSilva/Johnson
TIDES/COASTAL FLOODING...
CLIMATE...