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000
FXUS61 KPHI 202008
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
408 PM EDT Sat Apr 20 2024

.SYNOPSIS...
High pressure begins building in from the west this afternoon
following the passage of the cold front. The high will be in
place through Tuesday. A cold front passes by on Wednesday. High
pressure then returns and continues through at least Friday.

&&

.NEAR TERM /THROUGH SUNDAY/...
The cold front has crossed off shore and south of our region.
though there is a secondary cold front that is forecast to sweep
through later this afternoon into this evening which may bring
another surge of cold air advection.

Have seen some clearing, though stratocumulus has developed in the
wake of the front, especially for areas near and east of the
Delaware Valley. Consequently, adjusted cloud cover up for the next
few hours. That being said these clouds should dissipate closer to
evening as cooler air ushers in to the region.

With a secondary push of cooler and drier air coming in for tonight,
dewpoints will continue to drop through the 20s, lowest in areas
northwest of the urban corridor. There will be some high clouds
possible, but overall skies will be fairly clear, and with high
pressure building in from the Ohio Valley, we may see decoupling,
easing winds and some rather chilly temperatures into the 30s by
Sunday morning. Made no changes to the Frost Advisory for Sussex and
Warren counties. Will keep watching trends if it needs to be
expanded, but forecast temperatures in other areas are very marginal
for frost, and high clouds may come in toward morning that would
limit frost formation. Either way, would not rule out patchy frost
across the Lehigh Valley, though that may end up being more of the
rooftop variety rather than a threat to vegetation.

On Sunday, dry conditions for most of the region, though as noted by
the previous shift, some guidance continues to show the low off the
southeastern US coast taking a slightly further north track, which
could mean light rain showers edge in to southern Delaware, so have
kept a slight chance of showers there.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
Dry and tranquil weather is expected for the short term period
as a large high pressure will have control over the region. The
high will be initially centered over the Central Plains then
build east through Monday before shifting overhead Monday night.
The high will shift offshore on Tuesday ahead of the next
approaching system.

Skies clear quickly Sunday night as the low from daytime Sunday
moves into the western Atlantic. Skies will then remain clear
into daytime Tuesday. Will have to watch the development for
patchy frost across the Poconos/Lehigh Valley region both
Sunday night and Monday though at this time, development looks
marginal at best, mainly due to winds remaining slightly elevated
overnight around 5-10 mph. Lows each night will generally be in
the 30s to low 40s.

Highs will be in the upper 50s to low 60s on Monday and
increase to the mid-upper 60s on Tuesday.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
The high pressure that will keep us dry to start the week will
have completely vacated the area by Tuesday night. At the same
time, low pressure will be tracking across the northern Great
Lakes while moving into southern Quebec on Wednesday. An
associated cold front will be trailing southward from this low
which will pass through the area. Areawide showers are expected
with even a few rumbles of thunder possible depending on timing
and available instability. Best chances for this would be north
and west. Once the front clears the area, high pressure will
quickly build in from the west and remain within proximity of
the area to close out the work week. Another low pressure system
may begin to approach the area by next Saturday.

Temperatures through the long term period will run close to average
to a few degrees below-normal. Analogs toward the end of the week
and into next weekend, signal that a significant warm-up may be in
store to close out April.

&&

.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

Through Tonight...VFR with mainly clear skies. Winds ease fairly
quickly in the evening, but remaining NW at 10 kt or less. High
confidence.

Sunday...VFR expected. W-NW winds around 10-15 kt. Moderate
confidence.

Outlook...

Sunday night through Tuesday...VFR conditions expected with fair
weather.

Tuesday night into Wednesday...Sub-VFR conditions possible
(40-50%) with rain showers. An isolated thunderstorm is also
possible (15%). Daytime Wednesday is when chances for any
restrictions are highest.

Thursday...VFR conditions expected with fair weather.

&&

.MARINE...
Although winds may gust near 25 kt this evening, winds and seas are
expected to stay below SCA conditions through Sunday.

Outlook...

Sunday night through Tuesday...No marine headlines expected.
Fair weather.

Tuesday night through Wednesday...SCA conditions are possible
(35-45%) with winds gusting around 20-25 knots and seas building
to 3-5 feet. Rain showers expected.

Thursday...Sub-SCA conditions expected with fair weather.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...Frost Advisory from 2 AM to 8 AM EDT Sunday for NJZ001-007.
DE...None.
MD...None.
MARINE...None.

&&

$$

SYNOPSIS...AKL
NEAR TERM...Johnson
SHORT TERM...AKL/DeSilva
LONG TERM...AKL/DeSilva
AVIATION...AKL/Johnson
MARINE...AKL/Johnson