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000
FXUS61 KPHI 181052
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
652 AM EDT Thu Apr 18 2024

.SYNOPSIS...
A stationary boundary will remain situated across the area today as
weak low pressure meanders offshore. A cold front will pass through
the region early on Saturday with high pressure building in its
wake. High pressure will largely be in control through Tuesday
before another chance of precipitation returns Tuesday night into
Wednesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
High pressure over Quebec and New England with ridging extending
down into the northern Mid-Atlantic is associated with a
stubborn, cool and stable airmass that will generally hold in
place today and tonight. An occluding low pressure system
tracking across the Great Lakes has been advecting warm air
aloft over the cooler low-level air, but that low is beginning
to transfer to a developing coastal low off the NJ coast this
morning. That will only result in strengthening NE to N onshore
flow in the boundary layer today. Even while some warmer air
south of a stationary front has managed to creep into parts of
the Delmarva, do not expect that air to make much progress
northward. In many portions of our region, especially north and
east of Trenton, temperatures will stay very steady through the
day today, in the upper 40s and low 50s. While a mid- level
shortwave is passing through early this morning, keeping the
remnant of some fading convection alive in the form of a few
light showers, expect those to continue to fade while lifting
across northern NJ. Drizzle may be the predominant form of
precipitation across portions of the NJ shore, northern NJ, and
some of the ridges across SE PA this morning, perhaps even
lingering into this afternoon. That will be accompanied by some
areas of fog this morning, though that should not be dense
outside of the Pocono Plateau and adjacent ridge-lines. This
drizzle should not result in too much in the way of rainfall;
likely less than 5 hundredths of an inch today. Other areas,
particularly into the lower Delaware Valley southward, should
stay mainly dry today. A raw northeast breeze will add to the
very un-spring- like feel today, especially along the shore.
Southern Delaware may still manage to hit 70F, especially with
any breaks of sun, but that will be the exception in our area.

Tonight may still see a little patchy, mainly toward the
northern NJ shore, but overall expect dry conditions elsewhere,
with overcast skies, and easing northeast winds. Would not
totally rule out some patchy fog at times tonight into early
Friday morning, but expect just overcast skies in most
locations. Low temperatures will be several degrees cooler than
the previous night in most spots; mainly in the low to mid 40s.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
Continued cloudiness and cool conditions will persist through Friday
as the area remains wedged between a meandering low offshore and
cold front approaching from the west. High pressure to the north and
east looks to stay long enough that most of Friday should be dry,
although rain chances will increase later in the day and peak on
Friday night as the cold front passes through. Overall, PoPs on
Friday night will be between 20-40%, with greater chances further
west as atmospheric profiles are drier to the east. Temps on Friday
will be mostly in the 50s to around 60, with lows in the 40s to near
50 on Friday night.

Following the frontal passage, Canadian high pressure will drop
south into the High Plains on Saturday, while nosing its ridge axis
across the Eastern US. Other than some lingering showers early on
Saturday, most of the day will be dry with clearing skies. Despite
the frontal passage, the front really lacks any surge of "cold" air.
So, while drier air pushes into the region, temps will actually be
quite mild on Saturday as our boundary layer looks to be very-well
mixed with 850mb temps near 5-6C. Bringing this down to the surface
dry adiabatically, should result in highs at the surface in the mid
to upper 60s, possibly reaching 70 degrees in some spots. Mostly
clear skies and dry conditions will continue through Saturday night
with lows in the upper 30s to mid 40s.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
For the most part, the long term period will generally be tranquil
and quite seasonable, but will have to monitor a couple disturbances
along the way.

On Sunday and into Sunday night, will have to monitor the potential
for some showers to our south. This will be associated with a
stalled boundary sitting off the Southeast coast where a weak area
of low pressure develops along it before skirting out to sea.
Overall, any chance of showers looks to be minimal (up to a 30%
chance), and only as far north as Cape May at this time. The
remainder of the area will be dry despite increasing cloudiness.
High pressure then firmly remains in control on Monday and into
Tuesday. After this time, will have to watch back to the west as a
cold front will be approaching during the Tuesday night into
Wednesday timeframe. This is likely the next chance for some
widespread showers to occur across the area. In terms of
temperatures, we look to remain remain quite seasonable through the
middle of next week.

&&

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

Today...LIFR ceilings and IFR/MVFR VSBY for much of the region
with light mist or fog this morning. Both CIGs and VSBYs should
gradually lift heading into this afternoon, but the timing and
extent of improvement is not certain. Some drizzle may be
present early this morning, especially N and E of TTN. Winds
mainly NE 6-12 kt, but stronger and gusty along the NJ shore.
Low confidence in CIGs/VSBY today.

Tonight...Ceilings around 010 this evening may drop back into
the IFR category at times, but the overall forecast is for MVFR
ceilings to hold steady or even improve somewhat toward Friday
morning. VSBY mainly unrestricted, but would not rule out some
MVFR light mist or fog in the evening. Winds mainly NE 4-8 kt.
Low confidence.


Outlook...

Friday through Friday night...Sub-VFR likely with periods of low
clouds with rain showers especially during Friday night. SE winds
around 5-10 kt during the day, becoming SW winds around 5 kt or less
at night. Moderate confidence.

Saturday through Monday night...VFR expected. Mostly clear skies on
Saturday, mostly cloudy skies on Sunday, and clear skies returning
on Monday. W-NW winds expected through the period. High confidence.

Tuesday...VFR early with sub-VFR possible late with rain showers. S
winds. Low confidence.

&&

.MARINE...
Low pressure developing off the mid-Atlantic coast today,
combined with high pressure still holding across New England
will result in a tightening pressure gradient and increasing
NE/N winds expanding down the NJ coast, eventually reaching
Delaware by this evening. Those winds will peak with 25-30 kt
gusts, prompting Small Craft Advisories over all our ocean zones,
while seas build to 5-7 ft. As the low pressure system pulls
away tonight, NE winds will gradually ease toward 15 kt, but
seas will linger above 5 or 6 ft into Friday morning.


Outlook...

Friday through Friday night...The Small Craft Advisory is now in
effect for all ocean waters through 6 PM Friday due to seas around 5
feet. Seas may linger above SCA criteria into Friday night with a
chance for showers. No headlines are in effect for the Delaware Bay.

Saturday through Tuesday...Other than some showers possible on
Saturday, fair weather is anticipated. No marine headlines are
expected.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 6 PM EDT Friday for ANZ450.
     Small Craft Advisory from noon today to 6 PM EDT Friday for
     ANZ451.
     Small Craft Advisory from 3 PM this afternoon to 6 PM EDT
     Friday for ANZ452-453.
     Small Craft Advisory from 6 PM this evening to 6 PM EDT Friday
     for ANZ454-455.

&&

$$

SYNOPSIS...DeSilva
NEAR TERM...Dodd
SHORT TERM...DeSilva
LONG TERM...DeSilva
AVIATION...Dodd/DeSilva
MARINE...Dodd/DeSilva