859
FXUS61 KPHI 091943
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
243 PM EST Sun Nov 9 2025

.SYNOPSIS...
Low pressure and its associated strong cold front moves through
the area and offshore overnight. High pressure centered near
the Gulf Coast begins to build in through Tuesday, before
another cold front crosses our area later Wednesday. High
pressure then starts to arrive later Thursday and remains nearby
through the start of next weekend.

&&

.NEAR TERM /THROUGH MONDAY/...
A tricky and complex forecast is in store over the next 12
hours or so across the region with several boundaries over the
area. A weak low located near the mouth of the Delaware Bay is
slowly lifting north along a warm front which is the culprit for
showers across much of New Jersey and Pennsylvania this
afternoon. Across the Delmarva, showers have tapered off for the
moment, as the warm front has already cleared this area.
Temperatures in its wake have warmed into the low to mid 60s. As
the front continues to lift north, should see a break in shower
activity for the remainder of the area later this afternoon and
into this evening. In fact, temps may continue to slowly rise a
couple more degrees, even after sunset.

In any event, another round of showers is expected later this
evening as the primary low and cold front will be approaching
and crossing through the area. Timing with this round looks to
be generally after 8-11 PM from southwest to northeast and
continuing through much of the overnight hours. There also
remains a risk of an embedded thunderstorm south of the warm
front, however, this potential looks to be really isolated as
the better convective environment is well south of our forecast
area. In terms of rainfall amounts, an additional tenth to
quarter of an inch is possible, with locally higher amounts
possible. Although it`ll be warm early in the night, temps will
fall mainly into the 40s, with 30s in the Poconos following the
frontal passage.

By Monday morning, the cold front will be located off the coast
and low pressure will be tracking up through New England. Any
remaining showers are expected to cease shortly after daybreak.
Cannot rule out an isolated flurry up across the Pocono Plateau
as some colder air filters in. As the day progress, the
deepening upper-level trough will begin to pivot into the region
delivering a shot of modified, arctic air. With cold air
advection increasing under cyclonic flow, this should support a
pretty hefty strato-cumulus cloud deck, resulting in mostly
cloudy to at times overcast skies. Thus, high temperatures are
expected to peak by mid-day with highs only in the mid 40s to
mid 50s. Northwest, post-frontal winds will increase as well,
occasionally gusting around 20-25 mph. This will result in wind
chill values falling into the 20s and 30s, especially by late
afternoon.

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
A deepening upper-level trough will delivery a shot of modified
arctic air into the region, resulting in the coldest
temperatures so far this season Monday night through Tuesday.

The deep upper-level trough begins to move into the region on
Monday night with the trough axis located over the East Coast by
Tuesday morning. Some of the coldest air of the season, so far,
arrives as 850 mb temperatures will be as cold as -10C to -12C.
Despite partly to mostly cloudy skies, low temperatures will be
below freezing for all on Monday night, except perhaps for
areas along the immediate coast. Wind chill values should fall
into the teens and 20s. Some guidance also indicates some snow
showers, especially in the Poconos and Lehigh Valley overnight.
Looks like this is tied to lake-effect upstream, so wouldn`t be
surprised if some flurries survive the trip with such strong
flow at the surface and the trough overhead.

Temperatures on Tuesday will feel more like December than
November, with highs only in the low to mid 40s (30s in the
higher terrain). The other item of note, is that the Mid-
Atlantic region will be situated between strong low pressure
over the Canadian Maritimes and strong high pressure over
northern Gulf coast. This results in a tight pressure gradient
over the area. West-northwest winds near 15-25 mph are
anticipated with wind gusts 30-40 mph before diminishing later
in the day and especially Tuesday night. The area will remain
nestled within the upper-level trough through the afternoon
before departing the region by Tuesday night. This will allow
the airmass to moderate aloft. So, while it will still be quite
chilly, low temperatures for Tuesday night will not be as cold
compared to the night before.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Summary...Airmass moderates some before cooling some to start
the weekend. Any precipitation chances look rather limited as of
now.

Synoptic Overview...Shortwave energy should maintain a trough
from the Great Lakes and the Northeast Wednesday and Thursday.
This may amplify across the northeast Friday into Saturday
before shifting eastward with some ridging approaching from the
west into Saturday. At the surface, a cold front crosses our
area later Wednesday, then high pressure gradually approaches
from the west later Thursday before settling more into our area
Friday and Saturday.

For Wednesday and Thursday...While the main upper-level trough
has already departed, additional shortwave energy diving
southeastward from the Midwest and Great Lakes should maintain a
trough into the Northeast and Mid-Atlantic regions through
Thursday. As this occurs, surface high pressure centered across
the Southeast U.S. will track eastward. A notable breeze looks
to be present for both Wednesday and Thursday as a modest
pressure gradient persists. A weak clipper system will also
track across eastern Canada on Wednesday, with a weak cold front
crossing our area later Wednesday. Overall, this front looks to
be moisture-starved. Aside of a stray shower up into the higher
terrain, much of the area should remain dry. Temperatures will
be warmer compared to earlier in the week, but largely will
remain a few degrees below average.

For Friday and Saturday...The Mid-Atlantic region looks to be
situated on the backside of the aformentioned upper-level trough
as it may initially amplify Friday, then move away by later
Saturday. High pressure still looks like it will be centered off
to the west, so cool temperatures continue into the start of
next weekend. As of now, it looks mainly dry given the arrival
of surface high pressure.

&&

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

Rest of Today...Mainly MVFR conditions expected, although
temporary improvements to VFR are possible later this afternoon.
Showers likely through 21-22Z, before becoming more sporadic in
nature. East- southeast winds around 5-10 kt. Moderate
confidence.

Tonight...Prevailing MVFR conditions likely, with temporary
improvements to VFR early -- included a TEMPO group at some
terminals, where confidence is higher. Otherwise, showers likely
overnight with perhaps maybe a rumble of thunder near KACY/KMIV
but occurrence is not great enough to include in TAF at this
time. Southerly winds around 5-10 kt, becoming W-NW after 06Z as
a cold front passes. Low confidence, overall.

Monday...Primarily VFR ceilings, although a MVFR stratocumulus
cloud deck will move into the area, especially by mid-day. A
slight chance of a rain shower. West-northwest winds around 10
kt with gusts up to 20 kt possible. Moderate confidence.

Outlook...

Tuesday...VFR. West-northwest wind gusts 25-35 knots during the
day, diminishing some at night.

Wednesday through Friday...VFR. Wind gusts 20-25 knots,
diminishing each night.

&&

.MARINE...
No marine hazards are in effect through tonight. A Small Craft
Advisory has been issued beginning at 1 PM Monday for both the
Atlantic Coastal Waters and Delaware Bay.

Through tonight, southerly winds around 10-15 kt will quickly
transition to a west-northwest wind in wake of a cold frontal
passage. Seas of 3-4 feet. Showers likely with perhaps and
isolated thunderstorm. Dense marine fog possible.

On Monday, west-northwest winds will increase to around 10-20
kt with gusts up to 25 kt possible during the afternoon. Seas of
3-5 feet. Outside of developing SCA conditions, fair weather is
expected.

Outlook...

Monday night...Small Craft Advisory in effect. Northwest winds
increasing to 20-30 kts and seas building to 3-5 feet.

Tuesday...Westerly winds increasing to 25-35 kts with gusts up
to 40 kts possible. Seas 4-7 feet. Gale Watch is in effect
Tuesday through Tuesday evening.

Wednesday through Friday...Small Craft Advisory conditions
probable.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory from 1 PM Monday to 6 AM EST Tuesday for
     ANZ430-431-450>455.
     Gale Watch from Tuesday morning through Tuesday evening for
     ANZ430-431.
     Gale Watch from Tuesday morning through Tuesday evening for
     ANZ450>455.

&&

$$

SYNOPSIS...Gorse/Staarmann
NEAR TERM...DeSilva
SHORT TERM...Gorse/Staarmann
LONG TERM...Gorse/Staarmann
AVIATION...DeSilva/Gorse/Staarmann
MARINE...DeSilva/Gorse/Staarmann