548
FXUS61 KPHI 111100
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
700 AM EDT Wed Mar 11 2026

.WHAT HAS CHANGED...
Isolated to scattered severe thunderstorms remain possible
later today, however the threat over coastal NJ and DE has
lowered some.

&&

.KEY MESSAGES...
1. Warm and humid conditions today with record high temperatures
possible.

2. A pre-frontal trough may bring strong to severe thunderstorms to
portions of the area this afternoon, before a strong cold front
crosses through early Thursday morning.

3. Gusty winds and turning much colder Thursday in the wake of a
strong cold front.

4. A strong cold front moves through during Monday bringing
precipitation followed by a surge of colder air.

&&

.DISCUSSION...
KEY MESSAGE 1...Warm and humid conditions today with record high
temperatures possible.

Southerly flow increases today as low pressure deepens over the
eastern Great Lakes and high pressure remains parked over the
western Atlantic. This will result in a tightening pressure gradient
over the region with gusts up to 20-30 mph this afternoon. Warm air
will continue to flow northward where temps today are again expected
to top out in the mid 70s to low 80s, with 60s in the Poconos and
50s/60s along the coast. Highs may end up being a few degrees cooler
than yesterday though, mostly due to more clouds expected this
afternoon. See the Climate Section below for more information.


KEY MESSAGE 2...A pre-frontal trough may bring strong to severe
thunderstorms to portions of the area this afternoon, before a
strong cold front crosses through early Thursday morning.

Surface low pressure will strengthen as it tracks across the eastern
Great Lakes this afternoon and into southern Quebec tonight. This
will drag a strong cold front across the Mid-Atlantic region late
tonight into Thursday morning.

A warm and moist environment will be in place today with dew points
rising into the upper 50s to low 60s with mild temperatures. This
environmental set-up along with a pre-frontal trough developing over
central PA may allow for some strong to severe thunderstorms to
occur this afternoon. While storms may initiate to our west where
forcing is stronger near the pre-frontal trough, these storms are
expected to progress east by mid/late afternoon into the early
evening hours across our region. Strong southwesterly flow aloft in
addition to bulk shear around 40-50 kt will support strong shear
profiles favoring line segments with locally damaging wind gusts.
Cannot rule out some half-inch to quarter size hail along with the
potential for an isolated tornado. Overall, the greatest risk for
severe weather today favors areas further south and west where
stronger forcing overlaps the greater instability axis, however
the threat is conditional. The biggest caveat today will be how
much sunshine occurs and how unstable the area can get depending
or not if any morning precipitation occurs. Latest HREF
guidance depicts more clouds than sun to the north with some
breaks of sun to the south, mainly south and west of
Philadelphia. As a result, the Storm Prediction Center has
maintained a SLIGHT risk (Level 2/5) for severe weather this
afternoon for areas south and west of Philadelphia. There has
been a slight reduction to a MARGINAL risk mainly across coastal
NJ and DE where temperatures will be much cooler.

There may be a lull in activity overnight aside for some occasional
showers before the actual cold front arrives early Thursday morning.
Showers associated with the cold front itself look to mainly be post-
frontal, so the threat for any convective threat is minimal. Temps
will be very warm tonight until the front arrives and temperatures
tumble toward day break on Thursday.


KEY MESSAGE 3...Gusty winds and turning much colder Thursday in the
wake of a strong cold front.

As a strong cold front clears our area early Thursday morning,
robust cold air advection quickly develops from west to east. This
will result in mild temperatures to start the day, with temperatures
falling through the 50s and into the 40s for most areas through the
afternoon. A ripple of energy looks to ride along the front as it
clears the coast, and that should result in some additional forcing
for ascent behind the front. Some guidance shows rain changing to
wet snow for some areas before ending, however this tends to be
overdone as the dry air advection takes hold quicker. This drier air
may undercut the lingering midlevel forcing. Therefore, kept
precipitation as showery at this point with the PoPs lowering from
west to east during the day Thursday. Given this and plus with
temperatures above freezing, no snow accumulation expected. Strong
flow in the wake of the front along with robust cold air advection
will result in a period of deeper mixing occuring. The end result is
a gusty northwest wind through about mid afternoon before the wind
starts to diminish into Thursday evening. Peak gusts look to be
between 30-40 mph, and these winds along with falling temperatures
will enhance the chill through the afternoon. It turns much colder
Thursday night with most areas dropping into the upper 20s to low
30s before daybreak Friday.


KEY MESSAGE 4...A strong cold front moves through during Monday
bringing precipitation followed by a surge of colder air.

As low pressure tracks just to our north Sunday night into Monday, a
strong cold front will cross our area during Monday. A plume of
deeper moisture and stronger forcing for ascent should result in a
period of rain ahead of the cold front itself during Sunday night
and continuing for a time on Monday. A milder air mass should be in
place, therefore rain is expected. As some cold air begins to pour
in later Monday a transition to some snow before ending is possible
if enough moisture remains. The amount of precipitation and any snow
will be highly dependent on the timing of the system, how much
moisture is with it and how quickly the colder air moves in.

A robust period of cold air advection may follow into Tuesday,
resulting in a much colder air mass across our area. This may result
in high temperatures Tuesday struggling to reach 40 degrees across
most of our area.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Today...Mainly VFR with increasing clouds during the day.
Showers and thunderstorms possible in the afternoon, with the
greatest chance for the Lehigh Valley and I-95 terminals. Have
opted to include PROB30 groups mainly between 20-01Z. Shower and
thunderstorm activity is much less of a concern at MIV and ACY.
If any thunderstorm occurs, a brief period of IFR conditions
may be possible. South-southwest winds around 10-15 kt with
gusts up to 25 kt. Moderate confidence.

Tonight...Mainly VFR conditions expected for most of the night,
with MVFR and IFR conditions developing mainly after 08-10Z
with showers becoming increasing likely. Southwest LLWS
possible at all terminals around 40-50 kt. Southwest winds
around 10-15 kt will gradually veer and become west-northwest by
day break on Thursday with increasingly gusty winds.

Outlook...

Thursday...A period of MVFR ceilings possible, otherwise VFR
ceilings. Some showers mostly during the morning which could mix
with wet snow at some locations before ending could result in MVFR
visibilities at times. Northwest wind gusts 25-35 knots, diminishing
later in the afternoon and at night.

Friday...VFR. South to southwest wind gusts 25-35 knots, diminishing
some at night.

Saturday and Sunday...VFR overall.

&&

.MARINE...
A Small Craft Advisory has been issued for the Atlantic Coastal
waters beginning at 4 PM today. A Small Craft Advisory has also been
issued for the Delaware Bay beginning at 9 PM tonight.

South winds around 10-15 kt this morning are expected to increase to
around 20-25 kt later this afternoon. Southwest winds will then
further increase tonight with gusts up to 30 kt possible. Seas
around 2-4 feet will build to 4-6 feet.

Outside of SCA conditions, fair weather expected. Showers likely
with a slight chance of thunderstorms tonight.

Outlook...

Thursday...Small Craft Advisory issued, with conditions then
diminishing at night.

Friday...Small Craft Advisory conditions possible in the afternoon
and at night.

Saturday...The conditions should be lowering before Small Craft
Advisory criteria.

Sunday...Small Craft Advisory conditions probable, especially at
night.

&&

.CLIMATE...
Near record high temperatures are forecast for today, March
11th. Records for our climate sites are listed below:

Record Warmest Low Temperatures: March 11
Site............................Record/Year
Allentown (ABE).....................44/2006
AC Airport (ACY)....................48/1955
AC Marina (55N).....................51/2016
Georgetown (GED)....................55/1955 & 1986
Mount Pocono (MPO)..................47/1955
Philadelphia (PHL)..................54/1955
Reading (RDG).......................51/1955
Trenton (TTN).......................51/1955
Wilmington (ILG)....................48/1955

Record High Temperatures: March 11
Site............................Record/Year
Allentown (ABE).....................73/2021
AC Airport (ACY)....................79/1967
AC Marina (55N).....................70/1879
Georgetown (GED)....................77/2021
Mount Pocono (MPO)..................66/1977
Philadelphia (PHL)..................74/2021
Reading (RDG).......................77/2021
Trenton (TTN).......................73/2021
Wilmington (ILG)....................74/2021

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory from 9 PM this evening to 6 PM EDT
     Thursday for ANZ430-431.
     Small Craft Advisory from 4 PM this afternoon to 6 PM EDT
     Thursday for ANZ450>455.

&&

$$

DISCUSSION...DeSilva/Gorse
AVIATION...DeSilva/Gorse
MARINE...DeSilva/Gorse