945
FXUS61 KPHI 170723
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
223 AM EST Mon Nov 17 2025

.SYNOPSIS...
Strong low pressure will slowly move across the Canadian Maritimes
today and tonight. The center of high pressure slides mostly by to
our south by later Tuesday, then weak low pressure tracks eastward
from the Ohio Valley to the Mid-Atlantic Tuesday into Wednesday. A
warm front lifts north across our region later Thursday night and
Friday, followed by a weak cold front Friday night. A secondary cold
front may move through later Saturday followed by high pressure
later Sunday.

&&

.NEAR TERM /THROUGH TONIGHT/...
The last waves of some light rain and/or non-accumulating snow
showers, mostly sprinkles and/or flurries, will taper off during
the early morning hours. If there is any measurable
precipitation, it will only be a couple of hundredths of an inch
or so. For the overwhelming majority of the region, it will
only be a trace.

The region will continue to find itself between an upper trough
over the Northeast and high pressure building into the Great
Lakes and Ohio and Tennessee Valleys. Strong shortwave energy
will dive into the base of the trough early this morning and
into this afternoon. The sprinkles and/or flurries will taper
off late this morning, and the shortwaves will generally result
in partly to mostly cloudy skies later today.

The main issue will once again be the strong winds, though not
nearly as strong as they were on Sunday. West to northwest winds
will diminish to 10 to 15 mph with gust up to 20 mph early this
morning, then winds will quickly ramp up to 15 to 25 mph with
gusts up to 35 mph starting late this morning. Winds diminish
after sunset with loss of daytime heating, and winds become 5 to
10 mph tonight.

A seasonably chilly day on tap with temperatures almost 10
degrees below normal for this time of the year with highs in the
mid to upper 40s. Lows tonight will be in the upper 20s to
around 30, though warmer along the coasts. With skies clearing
out tonight, if winds can drop to less than 5 mph, especially in
outlying areas, radiational cooling may result in locally
colder temperatures.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
A colder air mass remains in place through Tuesday night. This is
with a west to west-northwest surface wind, and cyclonic flow aloft
gradually weakens into Tuesday night and thus less wind. There will
be a high pressure system building into the region later Tuesday and
this will relax the pressure gradient. In terms of temperatures,
lows in the 30s Tuesday night (some upper 20s across the far north).
Our highs on Tuesday are in the 40s and then the upper 40s to low
50s on Wednesday.

For Tuesday afternoon into Tuesday night, a low pressure system
starts to approach the region from the west and it still looks to be
on the weak side. Given the expected track being more southerly and
initially a dry air mass in place, the greatest potential for any
rain to develop is across Delmarva to near Philadelphia and across
southern New Jersey. As you get north of Philadelphia, the chances
for precipitation decrease. There is less confidence on
precipitation making it to the I-78 corridor, and especially as far
north as the I-80 corridor, given a southern track of the weak
surface low and drier air lingering the longest northward. If some
light precipitation does make it much farther north, some light snow
or a rain/snow mix could occur Tuesday night, especially for the
Poconos and far northwestern New Jersey. Any precipitation does look
to end early Wednesday morning and we trend drier through the day
although cloud cover should linger for much of the area.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
Summary...Turning milder overall and the precipitation chances
are mainly on the lower side.

Synoptic Overview...A weak shortwave trough embedded within the
mostly zonal flow Thursday shifts east and offshore of the Northeast
during Thursday, then some ridging builds across much of the East
Thursday night and Friday. An upper-level trough may then pivot
across New England Friday night and Saturday. Some ridging aloft
then builds again along the East Coast Sunday. At the surface, high
pressure across the Northeast and Mid-Atlantic shifts eastward
Thursday. A front well to our south lifts northward as a warm front
later Thursday night and Friday, then a weak cold front crosses our
area Friday night. A secondary cold front may arrive Saturday or
Saturday night, then high pressure gradually arrives from the west
during Sunday.

There is the potential for a few showers into Thursday with a piece
of upper-level energy moving through. Overall, not much
precipitation expected but we do stay mostly cloudy. Highs on
Thursday are forecast to be in the 40s to mid 50s. A warm front then
starts to lift north across our area Thursday night and Friday
morning and this could touch off some rain. The better potential for
any rain associated with this system looks to be ahead of the cold
front by later Friday into Friday night. The cold front then moves
through Friday night. Due to the warm front Thursday night, we do
trend warmer Friday with highs in the mid 50s to mid 60s.

A secondary cold front may cross our area during Saturday or
Saturday night. Overall the details are less certain with this cold
front due to timing, track and intensity of the low pressure system
that this front is associated with. In addition, a new low may
develop along the front in the Ohio Valley and this could slow the
eastward progression of it for at least a time. This system should
then shift eastward with high pressure gradually arriving from the
west and southwest during Sunday.

&&

.AVIATION /07Z MONDAY THROUGH FRIDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Early this morning (through 12Z)...VFR. Some light SHRA/SHSN are
possible until 09Z, but conditions will remain VFR. W-NW winds
10 to 15 mph with gusts up to 20 kt. Moderate confidence
overall.

Today...VFR. BKN CIGs 050-080. W-NW winds 15 to 20 kt with 35 to
35 kt gusts, diminishing after 21Z. High confidence.

Tonight...VFR. W-NW winds 5 to 10 kt. High confidence.

Outlook...

Tuesday...Areas of sub-VFR conditions possible at night due to some
rain, especially south of KPHL.

Wednesday and Thursday...Mainly VFR.

Friday...Sub-VFR conditions and some rain possible.

&&

.MARINE...
A tight pressure gradient over the waters will result in gale
force winds continuing through this afternoon, though there may
be a lull in the gales early this morning before ramping up
again shortly after sunrise. W-NW winds 15 to 25 kt with gusts
up to 35 kt. Winds diminish to Small Craft Advisory criteria
this evening, then SCAs may be needed, at least on the ocean
waters, tonight.

Outlook...

Tuesday through Thursday...The conditions are anticipated to be
below Small Craft Advisory criteria.

Friday...A period of low-end Small Craft Advisory conditions may
develop.

&&

.FIRE WEATHER...
Today, west to northwest winds will increase to 15 to 20 mph
with 30 to 35 mph gusts with MinRH values generally 35 to 40
percent, though possibly as low as 30 to 35 percent across the
eastern shores of Maryland and Delaware. Since RH Values will be
lower in Delmarva, and there was less in the way of rainfall
there this weekend, there is the potential for fire weather
concerns in those areas.

Will coordinate and collaborate with Fire Weather Partners to
see if any statements are needed across the southern half of the
forecast area.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Gale Warning until 6 PM EST this evening for ANZ430-431-
     450>455.

&&

$$

SYNOPSIS...Gorse/Guzzo
NEAR TERM...MPS
SHORT TERM...Gorse/Guzzo
LONG TERM...Gorse/Guzzo
AVIATION...Gorse/MPS
MARINE...Gorse/MPS
FIRE WEATHER...MPS