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000
FXUS61 KPHI 140007
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
807 PM EDT Sat Apr 13 2024

.SYNOPSIS...
High pressure will briefly be in control through Sunday morning
before an area of low pressure passes to the north of the region and
drags a cold front and a line a storms across the Mid-Atlantic
region Sunday night. High pressure builds back in Monday into
Tuesday, before a series of frontal boundaries and low pressure
systems affect the east coast Wednesday through Friday.

&&

.NEAR TERM /THROUGH SUNDAY NIGHT/...
As of 615pm...Clouds have continued to exit the area with mostly
clear skies now present over the southern two-thirds of the
area. Clouds are a bit more stubborn further north, but skies
will continue to clear as system pulls away. Wind gusts remain
between 25-35 kt through the rest of the day, but will diminish
quickly this evening with the loss of diurnal heating and
mixing after sundown. All shower activity has now ended.

For tonight, expect mostly clear skies and quiet weather.
Temperatures will get down into the low to mid 40s, with higher
elevations getting down into the upper 30s. A light westerly
breeze will continue through the night, around 5 to 10 mph. It
will be just warm enough and breezy enough to prevent any frost
from forming.

Sunday looks a bit more interesting, especially in the
afternoon and evening. The entire area will get into the warm
sector, with temperatures getting into the upper 60s and low to
mid 70s. A cold front will approach from the northwest, with
showers and thunderstorms developing out ahead of it, taking on
a linear mode. The highest instability will be to our west,
though with good forcing and relatively high shear, especially
in the low-levels, some organized convection will likely make
it into our area. The limiting factor is the instability over
our region, roughly 300-500 J/KG of MUCAPE. The steepest lapse
rates will also be well ahead of the better dynamics. Most of
the CAM guidance also has the line of storms coming in right
around sunset or even later.

Overall, everything really isn`t lining up perfectly for a
widespread severe event, and the thinking is that it will be more
localized to northern New Jersey, the southern Poconos, and the
northern Lehigh Valley. The Storm Prediction Center has an ENHANCED
risk for Carbon/Monroe County and a SLIGHT risk for northern
New Jersey and parts of the Lehigh Valley. The threat diminishes
significantly the further south you go as guidance has the line
fizzling rather quickly once the sun goes down. Delmarva and
far southern New Jersey actually will likely stay dry. The main
threat is damaging wind gusts as a 50-60 kt low level jet will
be overhead around the time the line of storms make it to our
area which could mix down with any stronger storms. Cannot rule
out a tornado as well with good low-level shear and SRH in the
0-1 km layer.

The cold front passes overnight and any showers should dissipate by
midnight or so. Temperatures will drop into the 50s overnight with
upper 40s in the Poconos/northern New Jersey.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
High pressure will largely be in control Monday and Tuesday with
afternoon highs in the low to mid 70s with nighttime lows in the
upper 40s to low 50s.

We will see dry weather through Tuesday night before rain chances
return during the late overnight hours Tuesday as our next system
approaches from the west.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Heading into Wednesday and continuing through the end of the work
week, the forecast becomes decidedly wetter. A pair of expansive
upper-level lows will be slowly transiting across the north central
United States and eastern Canada. This action will bring several mid-
level waves to the Eastern Seaboard and provide ample opportunities
for showers or a few thunderstorms to develop and move through the
area. As of now, the most organized of these waves looks to move
through the region Wednesday-Wednesday night and the highest PoPs of
the long term period (55-65%) are in this period to reflect that.
Overall though, it is still a bit premature at this time to say any
particular day through the back half of the week will be a complete
washout. High temperatures through the end of the work week remain
near to above normal in the mid 60s-mid 70s.

&&

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

Tonight...VFR with mostly clear skies. A few high clouds late.
W-NW winds around 10-15 kt with gusts up to 20 kt through
02-03Z, before diminishing and becoming more SW winds around
5-10 kt. High confidence.

Sunday...VFR expected at all terminals. Light SW winds early
around 5-10 kt will increase by 14-15Z around 10-15 kt with
gusts reaching up to 20-25 kt through the afternoon. Some
showers and scattered thunderstorms are anticipated to move in
during the late afternoon/early evening, mainly for KRDG/KABE.
Sub-VFR conditions are possible within any thunderstorm that
does occur. Moderate confidence overall.

Outlook...

Sunday Night...Any sub-VFR conditions will lift to VFR once the
cold front comes through.

Monday and Tuesday...VFR conditions expected with fair weather.

Wednesday and Wednesday night...Sub-VFR conditions possible (30-40%)
with showers. SSE winds around 10 kts to start, gradually increasing
to 15 kts by late afternoon with gusts up to 20 kts at night.

&&

.MARINE...
For the coastal waters north of Great Egg Inlet, the Gale
Warning has been replaced by a Small Craft Advisory as winds
have now lowered below gale force. The SCA is now in effect
until 4 AM on Sunday, mostly due to lingering seas above 5 feet.
Conditions will temporarily drop below SCA levels for the first
half of Sunday, before another SCA will likely be needed as S-SW
winds gust up to 25-30 kt on Sunday afternoon.

For the ocean waters south of Great Egg Inlet, a SCA remains in
effect until 10 PM this evening due to lingering seas around 5-6
feet. Likewise, a brief period of sub-SCA conditions are
expected, before another SCA will be needed on Sunday afternoon.

For the Delaware Bay, the SCA has been cancelled due to winds
diminishing below 25 kt. Winds should remain below SCA criteria
on Sunday for the Delaware Bay.

Outlook...

Monday and Tuesday...Small craft conditions gradually wind down
Monday morning. Otherwise, sub-SCA conditions expected through
Tuesday night

Wednesday and Wednesday night...Winds and seas gradually build as
the next storm system approaches. SCA conditions possible by
Wednesday night.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 4 AM EDT Sunday for ANZ450>452.
     Small Craft Advisory until 10 PM EDT this evening for
     ANZ453>455.

&&

$$

SYNOPSIS...AKL/MJL
NEAR TERM...DeSilva/Hoeflich
SHORT TERM...AKL/MJL
LONG TERM...AKL/MJL
AVIATION...DeSilva/Hoeflich/MJL
MARINE...DeSilva/Hoeflich/MJL