385
FXUS61 KPHI 181919
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
219 PM EST Tue Nov 18 2025

.SYNOPSIS...
A low pressure system tracks eastward from the Ohio Valley to
the Mid-Atlantic late today 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 into Monday.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
Increasing clouds this afternoon as the next storm system
approaches the region tonight. A westerly breeze this afternoon
bringing gusts of 15-20 mph at times will shift more
southwesterly late this afternoon and into the evening,
diminishing to less than 10 mph.

Tonight, a weak low will slide across the Mid Atlantic, bringing
a chilly rain across much of the forecast area and the potential
for some snow across the Pocono Plateau and higher elevations
across northwest NJ. A mix of rain and snow is also possible
across locations around the Lehigh Valley and areas along and
north of I-80 across northern NJ. Any accumulations are
forecast to be a trace to less than 1 inch at this time.

As the system approaches, antecedent dry air across the region
will delay the onset of precip reaching the ground, especially
further north where moisture advection will be weakest. Precip
will likely begin further south and west, beginning across the
Delmarva and spreading further north as the night continues.
High confidence precip will remain a cold rain south of the I-78
corridor, but moving further north and west uncertainty grows
regarding the potential for a wintry mix or snow. Weak low-level
southwesterly flow will eventually help bring sufficient
moisture into the region to support precip reaching the ground.
This said, uncertainty remains how quickly temperatures will
cool off when that occurs, particularly across the Lehigh Valley
and northwest NJ, where evaporational cooling is expected.
Forecast soundings currently show that even with evaporational
cooling, much of the Lehigh Valley and northwest NJ will see
sufficiently warm temperatures near the surface that supports
only some snow mixing in with rain. Snowfall at this time
continues to be most likely across the highest elevations in the
Poconos and extreme northwest NJ with accumulations less than
an inch. Some wintry precip may linger into the morning commute
for these locations, but is largely expected to begin tapering
off by daybreak Wednesday morning. In terms of rainfall, heavier
amounts are expected further south with a general 0.10-0.50 inches
forecast. Lows will be in the 30s across the board with low-30s
across the north and west while temperatures may rise some
across the southern areas overnight.

Wednesday starts out with some rain that departs quickly from
about the I-95 corridor eastward. Some additional rainfall may
fall in the morning, perhaps another 0.10-0.25 inches, bringing
the storm total rainfall to around 0.25-0.75 inches across the
board. There looks to be a fair amount of moisture lingering
across much of the region within a light north to northeast
wind, therefore the cloud cover may struggle to break up on
Wednesday. Some drier air across the northern areas however
during the afternoon may result in a bit more sunshine trying to
appear there. High temperatures are forecast to be in the 40s
to low 50s.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/...
High pressure initially centered over NY state Wednesday evening
will drift eastward towards New England by early Thursday. Meanwhile
a frontal boundary will linger near Delmarva with some weak impulses
moving through aloft in the upper level flow. This will tend to keep
skies mostly cloudy however it should remain mainly dry. The
exception will be across Delmarva where there could be some spotty
drizzle. With the lingering front, overnight lows will vary from the
upper 20s over NE PA and NW NJ to the upper 30s to around 40 over
Delmarva as well as SE PA and adjacent portions of southern NJ.

High pressure will weaken and continue moving off to the north and
east through Thursday. This will set up a weak warm advection
pattern by later in the day well ahead of the next system as it
starts to approach from the midwest. As a result, it will remain
mostly cloudy with a chance for some spotty drizzle around over
Delmarva and eastern PA. This shouldn`t really amount to anything if
it occurs and so we stayed with NBM POPs for Thursday which has
chances for measurable precip at less than 15 percent across the
area. Temperatures will continue to be a bit on the cool side for
this time of year with highs ranging from the 40s over NE PA and
northern NJ to the low to mid 50s over Delmarva and adjacent
portions of southern NJ. The greater Philadelphia area should see
highs within a couple degrees either side of 50.

The warm advection pattern starts to strengthen some for Thursday
night as the next system continues to approach and its warm front
starts to lift north. This will bring in chances for some light rain
by the overnight period, especially over eastern PA, northern
Delmarva, and the northern half of NJ. Overnight lows will remain
above freezing as they will generally range from the mid to upper
30s north to the low to mid 40s south.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
A frontal system associated with a progressive upper level low /
trough will affect the region Friday and Friday night with some
light rain. Temperatures will also moderate for Friday with highs in
the 50s to low 60s as the area briefly makes it into the warm
sector. A cold front will follow by Friday night into early
Saturday. Overall, rain amounts do not look to be very significant
and POPs for any given 12 hour period only max out around 30 to 50
percent. That said, this is due in part to differences in exact
timing between the different models and most areas should see at
least a little bit of rain at some point between Friday morning and
Saturday morning.

Differences in the forecast guidance increase as we go through the
weekend period with some guidance keeping a dominant long wave
trough over central and eastern Canada with an upper level low held
at bay over the SW CONUS. Meanwhile some of the ensembles depict a
more progressive trough lifting out through the weekend as the
upper level low initially over the SW starts to move eastward.
Overall, our forecast stayed close to the NBM and leans towards
the former of the two scenarios just described. This should
lead to generally decreasing POPs through the weekend however
it`s possible one more impulse could move through by later
Saturday into Saturday night bringing some light rain mainly to
the southern half of the forecast area. Confidence is low on
this though so our POPs are only around 30-40 percent or less.
Otherwise, temperatures this weekend should return to around
average for this time of year.

The beginning of next week looks to feature generally dry and
seasonable weather dominated by high pressure.

&&

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

Rest of today (through 00Z)...VFR with increasing and gradually
lowering clouds through the day. West-northwest winds 8-12
knots becoming west- southwest later this afternoon and
diminishing. Moderate confidence.

Tonight...VFR ceilings lower to MVFR after about 05z then to IFR
between about 06z-10z. Rain develops from west to east, mostly
in the 03z-06z timeframe. The rain should be rather light to
start with no visibility restrictions, then visibilities lower
overnight. Some snow may mix in at KRDG and KABE overnight, and
given low confidence just included a PROB30 for now. Winds becoming
light and variable overall. Low confidence in the timing details
and if snow occurs at KRDG and KABE.

Wednesday...IFR or MVFR ceilings in the morning improve to
primarily MVFR with VFR possible later in the afternoon. Some
rain mostly from around the KPHL area ends during the morning.
Light and variable winds becoming northeast to north 5-8 knots.
Low confidence.

Outlook...

Wednesday night through Thursday...Low stratus may result in MVFR
cigs.

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

Sunday...VFR conditions likely.

&&

.MARINE...
Marine conditions will remain below SCA criteria through
Wednesday. W to SW winds around 10 kts tonight will back to the
E and NE Wednesday. Some gusts may reach 15-20 kts at times
Wednesday afternoon. Seas around 2 feet.

Outlook...

Wednesday night through Sunday...The conditions are anticipated
to be below Small Craft Advisory criteria.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...None.

&&

$$

SYNOPSIS...Fitzsimmons/MJL
NEAR TERM...MJL
SHORT TERM...Fitzsimmons/MJL
LONG TERM...Fitzsimmons/MJL
AVIATION...MJL
MARINE...MJL