088
FXUS61 KPHI 311711
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
1211 PM EST Sat Jan 31 2026

.WHAT HAS CHANGED...
There is increasing confidence in wind and tidal flooding impacts
tonight into Sunday with the storm off shore. A Wind Advisory was
issued for southern Delaware and Cape May County NJ as well as
Carbon and Monroe Counties in the southern Poconos. For snow,
amounts have trended down slightly with this system.

&&

.KEY MESSAGES...
1. Cold temperatures combined with increasingly windier conditions
Saturday Night will lead to another night of dangerously low wind
chill values.

2. The rapidly deepening low off the coast will result in wind and
tidal flooding impacts, especially tonight into Sunday. Light snow
is possible for southern Delaware and far southeastern New
Jersey.

3. Below freezing temperatures are expected to persist across parts
of the area right through next week.

4. An active weather pattern will persist with two chances for some
snowfall mid to late week.

&&

.DISCUSSION...
KEY MESSAGE 1....Cold temperatures combined with increasingly
windier conditions Saturday Night will lead to another night of
dangerously low wind chill values.

Overnight tonight, radiational cooling will be limited by increasing
mid level clouds and a lack of winds decoupling. Thus, the ambient
(air) temperature will be higher tonight than what many areas
experienced early Saturday Morning. However, in spite of this, the
increasing wind, especially late tonight, will result in another
night of dangerously cold wind chills below zero across the region.
Therefore, the cold weather advisory remains in effect across the
region through mid morning on Sunday.


KEY MESSAGE 2....The rapidly deepening low off the coast will result
in wind and tidal flooding impacts, especially tonight into Sunday.
Light snow is possible for southern Delaware and far southeastern
New Jersey.

The main concerns with the off shore storm for our region are strong
winds and coastal flooding. There continued to be a slight shift
further south and east with the projected track of the system,
limiting the risk for snow (and light snow at that) to southern
Delaware and far southeastern New Jersey.

Continue to refine the forecast of the timing of the strongest winds
on land, now expected very early Sunday morning through Sunday
afternoon. This is mostly consistent with when the strongest
cyclogenesis is expected to occur (and thus, there will be a
stronger isallobaric component to the wind). The two areas where we
are most concerned about the wind impacts (notably wind gusts near
50 mph) are southern DE/far southeastern NJ and the southern
Poconos, but for different reasons.

Southern Delaware and far southeastern NJ will have the tightest
surface pressure gradient of the region very late tonight/early
Sunday morning (even here, the center of the low gets no closer than
300 miles away). Thus, the strongest winds here will come with the
(mostly) northerly winds before the shift to northwesterly winds
really gets started.

For the higher terrain of the Poconos (Carbon and Monroe Counties)
the wind risk is mostly from a low to mid level jet that begins to
develop by mid day Sunday. Thus the strongest winds in this area,
are more likely to be with the northwesterly winds through the
afternoon. Regardless of the exact wind speed, there is a potential
for a higher level of impacts in areas where snow and ice may still
remain on trees and wires.

With coastal/tidal flooding, minor tidal flooding is expected with
the Sunday morning high tide cycle from Barnegat Bay southward in
New Jersey and Atlantic coastal Delaware. A Coastal Flood Advisory
is in effect for the highest confidence areas to receive impacts
during the Sunday morning high tide. Areas further north, like
Manasquan and Sandy Hook could get very close to coastal flood
advisory thresholds, so will keep a close eye on tidal departures
over the next two high tides. At this point, tidal flooding is
unlikely for the northern shores of the Delaware Bay, the tidal
Delaware River and northeastern portions of the Chesapeake Bay. In
these areas, the wind direction is unfavorable for tidal flooding.

Minor flooding may continue near the times of high tide through
Monday, however the highest water levels and greatest impacts are
anticipated to occur during the Sunday morning high tide. The wind
direction being parallel and then switching to mostly off shore will
help limit coastal/tidal flooding impacts. However, it will be
working against higher astronomical tides with the full moon on
Monday, and increased swells from the off shore system. Further
complicating the impacts of tidal flooding impacts is ice that is
already developing on bays could be pushed onshore during high tide,
and flood waters could freeze on roadways.

Finally with snow, accumulation is likely to be limited to southern
Delaware and areas right along the southeastern NJ coast. Even here,
amounts are expected to be near or below one inch. For areas that do
get a bit of snow, the potential for strong winds concurrent or just
after the snow has fallen could lead to more significant impacts due
to blowing snow. The highest chance for snow is generally through
the overnight hours tonight, but there is up to a 20% chance that it
will linger into the daylight hours Sunday Morning.


KEY MESSAGE 3...Below freezing temperatures are expected to persist
across parts of the area right through next week.

While the broader, longwave, mid and upper level trough may shift
slightly further east in the wake of the coastal low, our region
will remain under a general northwest flow regime to start the new
week. As such, the cold pattern continues. Areas such as the coastal
plain of NJ and much of Delmarva are likely to get above freezing
Tuesday and again Wednesday, while most of the rest of the region is
forecast to stay below freezing. This current stretch of below
freezing temperatures began last weekend (Jan 23 through 26 - varies
depending on the site), which means if areas don`t get above
freezing Tuesday or Wednesday, this stretch of below freezing
temperatures is on track to be at least 2 weeks long. The longer
this stretch continues, there will be an increasing risk for more
impacts to infrastructure including frozen pipes and widespread ice
on waterways. This would be a top five longest stretch of below
freezing temperatures for many of our climate sites.


KEY MESSAGE 4....An active weather pattern will persist with two
chances for some snowfall mid to late week.

The first system may be a weak low that slides just to the south of
the region, possibly grazing the forecast area with light snowfall
on Wednesday. Some models are depicting a low developing in response
to a lee side trough over E NM/TX panhandle and then progressing
east across the southeastern portion of the U.S. and eventually off
shore through early to mid next week. As has been the case with the
last several events, the exact track of the low will have
implications on if our region will see snow with this system and how
cold the late week period will be. The farther south this low
tracks, the less likely our region will see snow, but the more
likely we will have very cold conditions Thursday and Friday. A
blend of guidance is a reasonable middle of the road solution this
far out, with a broad 20 to 40% chance for precipitation across the
area around about next Wednesday, and temperatures about 5 to 10
degrees below normal.

The second system looks to be an Alberta Clipper moving through
Friday night into Saturday morning bringing a potential for light
snowfall across the region. NBM blend of guidance currently brings a
25-35% chance for snowfall with this system as the polar jet brings
a trough across the Great Lakes and Northeast region. It is notable,
however, that guidance currently has an upper level trough
associated with the subtropical jet pivoting across the Southeastern
US late Thursday into early Friday, just out of sync with the trough
associated with this clipper system Friday night. Should the timing
of either trough shift closer to the other and end up phasing, a
more robust system could be in the works. The confidence this far
out is naturally very low, but something we will continue to
monitor.

&&

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

Rest of Today (through 00z)...Primarily VFR though some periods
of MVFR CIGs possible (30-55% chance) at the I-95 terminals.
Satellite and upstream observations show some stratus moving in
the direction of these terminals, and could produce SCT/BKN
FL025-FL030 CIGs between 20z-00z for KTTN/KPNE/KPHL/KILG.
Stratus is over KRDG and CIGs are currently just above FL030,
so will have to watch how things trend. Winds out of the north
around 10 kt. Low to moderate confidence in timing and extent
of any MVFR CIGs.


Tonight...Primarily VFR at the I-95 and Lehigh Valley terminals,
with a period of prevailing MVFR likely (50-70% chance) at
KACY/KMIV. Short-range model guidance continues to trend
further east with the precipitation shield, so snow and
potential IFR conditions are unlikely at this time. Cannot rule
out some light snow (15-20% chance), but have a rather high
confidence that any restrictions will be from MVFR CIGs between
FL020-FL030 between 03z and 12z. Low confidence in timing,
moderate confidence in extent and occurrence of restrictions
(MVFR or VFR). Winds increase after 06z out of the north around
10-15 kt and gusts 20-25 kt.

Sunday...Primarily VFR as any restrictions at KMIV/KACY should
lift after 12z. Winds out of the north/northwest around 15-20 kt
and gusts 20-30 kt. Gusts up to 35 kt possible at KACY. Moderate
confidence.

Outlook...

Sunday night...VFR. Northwest winds around 10 kts gusting to
15-20 kts.

Monday and Tuesday...VFR.

Wednesday...Sub VFR conditions possible as the next low
pressure system tracks by to our south and potentially brings
the area some snow.

&&

.MARINE...
Winds will begin to increase this afternoon as the off shore storm
intensifies. Through the center of the storm is not expected to get
any closer than 300 nmi to the coastal waters of Delaware and New
Jersey, widespread gale conditions are expected to develop on all
area waters by late tonight. Gale conditions are likely to develop
first on the Atlantic coastal waters near Fenwick Island as early as
this evening, gradually increasing further north. The risk for storm
force gusts has decreased, now about 10 to 25% chance, with the
highest chance south of Cape Henlopen. Therefore, have issued a gale
warning for the coastal waters and Delaware Bay through Sunday.

With the increasing winds, very cold air, and significant wave
heights near 10 ft in some areas, freezing spray will become a big
concern, especially with the period of strongest winds. A heavy
freezing spray warning has been issued for the coastal waters. On
the Delaware Bay, where lower waves, and less open water will mean a
lower threat (as compared to the coastal waters) a freezing spray
advisory is in effect through Sunday.

Outlook...

Sunday night through Monday...winds and seas are expected to
diminish, but SCA conditions are likely to persist into Monday.
Freezing spray possible.

Tuesday...winds and seas are expected to be below SCA criteria.
However, with wind gusts 15 to 20 kt possible, light freezing spray
may remain a concern through this period.

Wednesday...Sub SCA with winds expected to further diminish compared
to Tuesday.

&&

.CLIMATE...
On January 30th, the record coldest high temperatures was set
at Georgetown, DE with 20 degrees and tied at Mount Pocono, PA
with 7 degrees.

Potentially record-breaking cold is expected this weekend with
a chance for some of our climate sites to set record low
temperatures and/or record cold high temperatures.

Record Low Temperatures and Record Low High Temperatures for:

January 31

Site    Low/Year       Low Max Temperature/Year
ABE       -9/1948             14/2019
ACY        0/1948             20/2019
PHL        3/1948             18/2019
ILG        3/1948             19/2019
RDG       -5/2019             14/2019
TTN       -1/1920             16/2019
MPO      -15/1908              4/2019
GED        1/1948             23/2019
55N        4/1948             19/2019

Not all records will be challenged or broken, but some
could fall over the coming days and nights.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Cold Weather Advisory until 10 AM EST Sunday for PAZ054-055-
     060>062-070-071-101>106.
     Wind Advisory from 6 AM Sunday to 1 AM EST Monday for PAZ054-
     055.
NJ...Cold Weather Advisory until 10 AM EST Sunday for NJZ001-
     007>010-012>027.
     Wind Advisory from midnight tonight to 4 PM EST Sunday for
     NJZ023-024.
     Coastal Flood Advisory from 5 AM to noon EST Sunday for NJZ020-
     022>027.
DE...Cold Weather Advisory until 10 AM EST Sunday for DEZ001>004.
     Wind Advisory from midnight tonight to 4 PM EST Sunday for
     DEZ003-004.
     Coastal Flood Advisory from 5 AM to noon EST Sunday for DEZ003-
     004.
MD...Cold Weather Advisory until 10 AM EST Sunday for MDZ012-015-
     019-020.
MARINE...Gale Warning from 10 PM this evening to 4 PM EST Sunday for
     ANZ430-431.
     Freezing Spray Advisory from 10 PM this evening to 4 PM EST
     Sunday for ANZ430-431.
     Gale Warning from 10 PM this evening to 6 PM EST Sunday for
     ANZ450-451.
     Heavy Freezing Spray Warning from 10 PM this evening to 6 PM
     EST Sunday for ANZ450-451.
     Small Craft Advisory until 6 PM EST this evening for
     ANZ452>455.
     Gale Warning from 6 PM this evening to 6 PM EST Sunday for
     ANZ452>455.
     Heavy Freezing Spray Warning from 6 PM this evening to 6 PM
     EST Sunday for ANZ452>455.

&&

$$

DISCUSSION...Johnson/MJL
AVIATION...Hoeflich/Johnson/MJL
MARINE...Johnson/MJL