National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS61 KPHI 182346
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
746 PM EDT Thu Apr 18 2024

.SYNOPSIS...
High pressure over the Gulf of Maine will slowly track out to
sea on Friday. Meanwhile, low pressure north of the Great Lakes
will slowly track east and will drag a cold front across the
region Friday and Friday night. The front becomes stationary
south of the Mid-Atlantic through the weekend as high pressure
builds in from the north. The next frontal system looks to
affect the area Tuesday night through Wednesday.

&&

.NEAR TERM /THROUGH FRIDAY/...
4PM discussion...
A stalled frontal boundary is positioned over southern
Delaware, with upper 60s/low 70s south of the front under partly
cloudy skies, and 50s/low 60s north of the front with overcast
skies and some patchy drizzle. This will be the general theme
through the rest of today, though patchy drizzle should
gradually cease from south to north as the afternoon goes on.

For tonight, expect relatively dry and quiet conditions. Some
patchy fog is possible but guidance has become less enthusiastic
about fog chances. Winds will diminish slightly but a weak
onshore flow remains. Expect overcast skies and temperatures
falling down into the low to mid 40s.

Friday will start out dry as the weak onshore flow regime
persists. Cloudy conditions are expected through the day as low-
level moisture continues to funnel in. A cold front will
approach, with some afternoon showers possible (20-40% chance)
from the I-95 corridor on west. Not expecting anything impactful
overall though as the strongest forcing will be well to the
north and there will be no instability. Rainfall amounts will
only be a few hundredths for those that see any rain Friday
afternoon. Temperatures will get into the upper 50s/low 60s.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
Cold front slowly works its way across the region Friday night
and will be offshore by Saturday morning. There does not look to
be much lift or moisture associated with this front, and QPF
should be on the order of 1/10 inch or less. Perhaps up to 2/20
inch of QPF is possible for southern Delaware as low pressure
passes through the Mid-Atlantic, but well south of the local
forecast area.

The front continues to move offshore through the weekend, but
the tail end of the front will extend back through the Mid-
Atlantic and back through the Gulf Coast. High pressure builds
in from the north and west and conditions dry out for most of
the weekend. Low pressure develops on that old front will will
pass through the Mid-Atlantic on Sunday, but this system looks
to be well south of the region, and any rainfall should be south
of Delaware.

Near normal temperatures on tap for Saturday with highs in the
mid and upper 60s. Cold air advection will be underway for
Saturday night and Sunday with a below normal air mass spreading
into the region. Lows Saturday night will be in the 30s and low
40s, and then highs on Sunday will be in the upper 50s to low
60s.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
High pressure slowly works its way through the East Coast for
the start of the new week, moving offshore and south of the
region by Tuesday. Low pressure approaches from the west on
Tuesday and moves north of the region Tuesday night through
Wednesday. For now, will generally carry chance PoPs for that
timeframe, but there will be a slug of likely PoPs for the
southern Poconos and Lehigh Valley Tuesday night. Cold front
passes through behind the departing low on Wednesday. Conditions
dry out for Thursday.

Temperatures return to normal levels for the first half of the
week, dropping below normal for the end of next week.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas...

Rest of Tonight...Prevailing MVFR and gradually lifting
ceilings, possibly going to VFR late. Winds out of the east
around 5-10 kt. Moderate confidence.

Friday...Ceilings bordering on MVFR/VFR with VFR visibilities.
Winds veering to more of a southeasterly direction around 5-10
kt. Low confidence overall in timing of VFR and whether it will
be prevailing VFR or MVFR.

Outlook...

Friday night...Sub-VFR conditions in SHRA.

Saturday through Tuesday...VFR. No significant weather.

&&

.MARINE...
A Small Craft Advisory is in effect currently for all the ocean
zones. SCA conditions are expected on the ocean waters through
late Friday night as seas will be around 4 to 8 feet. Some
gusts in the 25-30 kt are possible off the New Jersey coast
through this evening. Vsby restrictions possible in showers
Friday night.

On the Delaware Bay, no marine headlines are anticipated as
east/northeast winds will remain around 10-15 kt.

Outlook...

Saturday through Tuesday...A prolonged period of sub-SCA
conditions and fair weather.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 6 AM EDT Saturday for ANZ450>455.

&&

$$

SYNOPSIS...MPS
NEAR TERM...Hoeflich
SHORT TERM...MPS
LONG TERM...MPS
AVIATION...Hoeflich/MPS/RCM
MARINE...Hoeflich/MPS/RCM