843
FXUS61 KPHI 241124
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
624 AM EST Sun Nov 24 2024

.SYNOPSIS...
The region will be in a cool and brisk northwest flow through Sunday
as we are between low pressure over Nova Scotia and high pressure
over the Mississippi Valley. The area of high pressure will be
centered over the Eastern United States late Sunday into Monday. The
next fast moving cold front is expected to cross our region Tuesday.
A coastal low will be near our region Thanksgiving into Friday.

&&

.NEAR TERM /THROUGH TONIGHT/...
Strong low pressure continues to meander over Nova Scotia early this
morning and will gradually lift into the Gulf of Saint Lawrence this
evening. High pressure is also building to our southwest which will
move its way into the Mid-Atlantic region tonight.

As a result, a similar day to yesterday is expected. Brisk northwest
winds continue as our area remains on the outer periphery of the
cyclonic flow. So we`ll encounter another round of blustery
conditions again today, however should be a bit more tame compared
to yesterday as the low is located a bit further away. Nonetheless,
wind gusts of 25-35 mph are possible under partly to mostly cloudy
skies and highs mainly in the upper 40s to mid 50s. A slight
chance of a lake-effect rain shower cannot be ruled out across
the southern Poconos and Lehigh Valley as well.

For tonight, the pressure gradient finally begins to relax as high
pressure noses in from the southwest. Looks like winds may be just
elevated enough to prevent a totally efficient radiational cooling
night, but given mostly clear skies and light winds, some localized
areas will likely decouple. Lows tonight will mainly be in the 30s
with isolated 20s in the most sheltered locales.

&&

.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
Focus remains on a low pressure system that will be moving from
the Great Lakes region into the Canadian Maritimes through this
period. This low will be responsible for a warm front on Monday,
a Cold front on Tuesday, and a brief chance for rain in
between. Rain amounts have increased slightly, but the fast
moving nature of this system means that most places should still
see less than a quarter inch of rain. Despite the best chance
for rain generally being overnight Monday night into Tuesday
morning, temperature profiles throughout the region should be
warm enough to support all rain.

As far as temperatures, highs on Monday will be about 5 degrees
above normal, ranging from the mid 40s to near 60, despite the
strongest warm air advection likely not arriving until late in
the day. At this point, guidance favors the cold front arriving
late enough on Tuesday that Tuesday will actually be the warmest
day of this period, with highs ranging from the upper 40s to
lower 60s. The cold air advection will be in full effect on
Wednesday as temperatures will be about 10 degrees lower than
the highs on Tuesday.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
All eyes in the long term are on the Thanksgiving/Friday system.

What has changed: guidance with the 00Z model run generally
trended further NW with the track of the low (which would favor
mostly rain). That being said, there is still a wide range of
possibilities in how deep and intense the low will be and how
fast it will be crossing through our region.

Continued with a blend of guidance, which as mentioned would
favor mostly rain, with the exception of the higher terrain of
the southern Poconos and NW NJ. The guidance that depicts a
track further south and east also is depicting the low weaker
than the further northwest tracks. Thus, even if the trend goes
back southeast with the track, at this point, it doesn`t look
like it would result in widespread snow across the region. Stay
tuned for more updates with this system, since we will be
monitoring it into early next week and more details will become
available as we get closer to the time of the event.

While it still looks to be a relatively fast moving system while
it is tracking close to our region Thursday into Friday, the
center could retrograde Saturday into Sunday, resulting in
prolonged northwesterly flow and persistent cold air advection
for next weekend.

&&

.AVIATION /11Z SUNDAY THROUGH THURSDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

Today...VFR with SCT/BKN clouds in the morning, clearing during the
afternoon. West winds around 10-15 kt with occasional gusts up to 25
kt. High confidence.

Tonight...VFR with mostly clear skies. West winds around 5-10 kt,
becoming light and variable overnight. High confidence.

Outlook...

Monday...VFR.

Monday night and Tuesday...Brief period of MVFR possible with rain.
W winds gusting up to 30 KT Tuesday afternoon.

Wednesday...VFR.

Wednesday night through Thursday...Widespread MVFR and IFR
conditions with low clouds and visibility.

&&

.MARINE...
The Gale Warning continues for the northern-most marine zone
until 1 PM today. A Small Craft Advisory is now in effect for
the coastal waters south of Cape May and the Delaware Bay until
4 PM and until 7 PM for the waters offshore Manasquan Inlet to
Cape May.

West-northwest winds around 20-25 kt with gusts up to 35 kt are
expected through this morning before diminishing to 15-20 kt with
gusts up to 25-30 kt this afternoon. Winds will continue to diminish
tonight around 10-15 kt. Seas of 3 to 5 feet today, lowering to 3
feet or less tonight.

Outlook...

Monday...Winds and seas should stay below SCA criteria.

Tuesday/Tuesday night...Expect an abrupt shift to W winds behind a
cold front Tuesday morning. Wind gusts up to 30 kt expected behind
the front.

Wednesday...Winds should remain below 25 KT before dawn Wednesday
while seas diminish below 5 ft. Once that happens, expect conditions
to stay below SCA criteria through at least Wednesday night.

Thursday...Depending on the exact track and timing of a coastal low,
seas and winds may build close to SCA criteria by Thursday night.

&&

.CLIMATE...
Driest autumn (Sep-Nov) on record, and any 3-calendar month
period on record, plus current status as of 6 PM, Nov 22:

                   9/1-11/22   Driest          Driest 3         Year/
Site              2024 precip  Autumn Year  Calendar months    months
Allentown (ABE)       2.86      3.81  1922      3.58        Oct-Dec 1928
A.C. Airport (ACY)    2.23      3.34  2001      2.35        Oct-Dec 1946
A.C. Marina (55N)     1.61      2.89  1941      2.52        Aug-Oct 1895
Georgetown (GED)      1.41      2.67  2001      2.20        Aug-Oct 2024
Mount Pocono (MPO)    5.06      4.21  1931      3.36        Oct-Dec 1928
Philadelphia (PHL)    2.20      2.37  1922      2.37        Sep-Nov 1922
Reading (RDG)         2.34      2.89  1922      2.89        Sep-Nov 1922
Trenton (TTN)         2.12      3.18  1922      2.66        Jun-Aug 1966
Wilmington (ILG)      1.85      3.17  1922      3.17        Sep-Nov 1922

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 4 PM EST this afternoon for ANZ430-
     431-454-455.
     Gale Warning until 1 PM EST this afternoon for ANZ450.
     Small Craft Advisory until 7 PM EST this evening for
     ANZ451>453.

&&

$$

SYNOPSIS...Franklin/Johnson/OHara
NEAR TERM...DeSilva
SHORT TERM...Johnson/OHara
LONG TERM...Johnson/OHara
AVIATION...DeSilva/Johnson
MARINE...DeSilva/Johnson
CLIMATE...