385
FXUS61 KPHI 111609
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
1209 PM EDT Tue Mar 11 2025

.SYNOPSIS...
High pressure will be over the area through Tuesday, and then a
cold front passes through the region Tuesday night. High
pressure settles over eastern Canada Wednesday through Friday. A
warm front lifts north on Friday night, and high pressure
establishes itself over the Mid-Atlantic this weekend until a
strong cold front passes through the region late Sunday. High
pressure returns on Monday.

&&

.NEAR TERM /THROUGH TONIGHT/...
The warmest day so far this year is expected for today under
sunny skies with a dry southwest breeze. West to southwest
flow pattern will continue to prevail aloft through mid week. At
the surface, low pressure passing well north of the area this
morning will push a cold front into the area overnight as high
pressure builds to the north and northeast in its wake.

Today`s pattern is likely to be a classic case of temperatures
far exceeding model guidance for inland areas. Modest southwest
flow, approaching cold front (prefrontal troughing), dry air,
and sunny skies throughout the day. With this in mind, we`ve
maintained the temperature forecast being above guidance, with
afternoon highs ranging from the upper 60s to low 70s in most
areas (50s for the immediate coastal areas). Would not be
surprised if a few stations in the Delaware Valley and inland
Delmarva briefly get into the mid 70s. South to southwest winds
increasing to near 10-15 mph, strongest northwest of I-95 where
some gusts near 20-25 mph are possible by this afternoon. An
overall stellar day for mid-March!

While record highs should largely be safe today, March 11th is
a "low hanging fruit" day with daily record values mostly in the
mid 70s. See the Climate section below for more details.

With relative humidity falling into the 20-30% range this
afternoon, we`ll have continued fire weather concerns for some
areas where winds are a bit stronger. See the Fire Weather
section below for more details.

A back door front will drop down from the north beginning late
this evening into the overnight, with surface winds shifting
north to northeast near 10 mph. Low temperatures by Wednesday
morning will be near 40 degrees south of I-78, and in the low
to mid 30s near and north of I-78.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
A cooler airmass spreads into the region for Wednesday. Dry
conditions are expected with high pressure building into eastern
Canada, with the base of the high down by New Jersey. Onshore
flow will setup that, given ocean temperatures in the low to mid
40s, should result in highs on in the 50s for most areas,
though inland areas should get into the 60s.

High pressure may retreat briefly Wednesday night with a weak
cold front passing through the region, riding along a mid-level
shortwave. This may tough off some light rain showers, with some
light snow showers in the southern Poconos. One thing to
monitor for Wednesday night onward, is that projected dew points
look to be in the mid 40s or so, and if these dew points are at
or above ocean temperatures, there could be fog issues,
especially along the coasts.

Otherwise, dry conditions continue Thursday and Thursday night
with high pressure nearby and similar temperatures to Wednesday
with the continued onshore flow.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
High pressure remains over eastern Canada through Friday before
departing Friday night. Another dry day results with
temperatures potentially a few degrees warmer as mid-level winds
begin to turn more southerly.

A warm front lifts north through the region Friday night, and
then strong southerly flow sets up, allowing for warm air
advection and highs in the upper 60s and low 70s this weekend.
Strong low pressure lifting north of the region will drag a cold
front east on Sunday. A secondary low forms on this front as an
upper trough digs in behind the front. Breezy conditions set up
on Sunday with southerly winds 15 to 20 mph with 25 to 35 mph
gusts. Showers develop Sunday afternoon and evening with the
passage of the cold front. Ensemble guidance and model soundings
indicate pretty limited instability with modest at best lapse
rates in the low to mid levels. As a result, reduced the thunder
mention to areas mainly in the southern half of the region.
However, given that we are looking at Day 6, we will continue to
monitor the potential for stronger thunderstorms, given the
overall strong dynamics of the larger system.

Turning much cooler and drier behind the cold front on Monday
with highs generally around 60.

&&

.AVIATION /16Z TUESDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Rest of Today...VFR/SKC. South to southwest winds gradually
increasing to 7-12 kt, with gusts up to 20 kt possible at
KRDG/KABE. High confidence.

Tonight...VFR with increasing high clouds. Initially south to
southwest winds 5-10 kt will shift north to northeast behind a
cold front between 03-09Z from north to south. High confidence
in prevailing conditions, but lower confidence on exact timing
of the wind shift.

Outlook...

Wednesday...VFR.

Wednesday night through Saturday...Mainly VFR, but potential
for sub-VFR conditions at night in fog and/or low stratus, most
likely at coastal terminals.

&&

.MARINE...
No marine hazards expected through tonight. Light winds
settling out of the south around 10 kt this afternoon. Seas 1-2
feet. The winds will shift north to northeasterly late tonight
and increase slightly to near 10-15 kt as a cold front pushes
south. Seas building to 3-4 feet tonight. As the cold front
passes overnight, some brief gusts near 20-25 kt are possible,
though these should not prevail long enough to warrant an
advisory. Fair weather.

Outlook...

Wednesday through Thursday...Mostly sub-SCA conditions, but
seas may build close to 5 ft on the ocean waters, most likely
Wednesday night into Thursday.

Friday...Sub-SCA conditions.

Saturday...SCA conditions likely.

&&

.FIRE WEATHER...
A Special Weather Statement is in effect until 8 PM today for
all our PA counties and NJ counties, north of I-95 corridor.

For today, south-southwest winds increasing to 10-15 mph across
much of the area, with gusts near 20-25 mph possible this
afternoon across our eastern Pennsylvania and northern New
Jersey areas. MinRH values will be in the 20-30% range with
afternoon high temperatures near 70 degrees and plenty of sun.

For Wednesday, winds will be considerably lighter and have more
of an onshore component. East winds around 10-15 mph with MinRH
values in the 25-35% range. Considering improving RHs and
lighter winds, there does not appear to be a enhanced risk for
fire spread at this time.

&&

.CLIMATE...
Near record breaking temperatures are forecast this afternoon.
Records for our climate sites are listed below:

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...None.

&&

$$

SYNOPSIS...AKL
NEAR TERM...DeSilva/Staarmann
SHORT TERM...AKL/MPS
LONG TERM...AKL/MPS
AVIATION...AKL/DeSilva/Staarmann
MARINE...AKL/Staarmann
FIRE WEATHER...WFO PHI
CLIMATE...WFO PHI