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000
FXUS61 KPHI 240544
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
144 AM EDT Wed Apr 24 2024

.SYNOPSIS...
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A low pressure will track through Ontario and Quebec today,
dragging a cold front will across our region. High pressure
then arrives from the Great Lakes Thursday before shifting to
our northeast and east during Friday. A warm front should lift
north of our area late Saturday, then a cold front gradually
approaches later Monday.
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.NEAR TERM /THROUGH TONIGHT/...
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Latest analysis depicts the approaching cold front as extending
from south of Chicago northeastward across southern Michigan and
into southern Ontario and southern Quebec. This front will make
steady progress southeastward today, reaching our region this
evening and clearing the area after midnight tonight. Ahead of
the front, modest warm advection will result in plenty of clouds
early this morning, perhaps with a few sprinkles or very
isolated showers, but low levels remain quite dry and the system
is overall moisture-starved, so not expecting much. After the
initial clouds break, we should warm up to within a few degrees
of 70 across most of the region this afternoon, but there will
be just enough instability ahead of the upper trough and surface
front to promote some mainly isolated showers to develop during
the afternoon. There could be just enough instability for a very
isolated thunderstorm, mainly Lehigh Valley and Poconos/NW NJ.
For sure, shower coverage will be a bit higher in the Poconos
compared to the rest of the region, but still scattered at best.
Despite the front not arriving until evening, winds for much of
the day will already shift to west to northwest as early as
midday, with gusts increasing up to 20-25 mph. Overall, not a
bad day, but not as nice as yesterday aside from yesterday`s
chilly morning.

Tonight, Canadian high pressure builds southward and reinforcing
cool, dry air mass pushes southward. Think winds staying up and
the dry air limit frost potential, but temps may still reach
freezing in parts of northern NJ where growing season is active,
so have maintained freeze watch there for the time being. Lows
overall will be chilly, with 40s warmest spots, most areas 30s,
and coldest locales 20s.
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.SHORT TERM /THURSDAY THROUGH FRIDAY/...
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A notably colder and dry air mass will be in place Thursday
despite a mainly sunny sky with high temperatures mostly in the
50s. An onshore wind will also keep it even cooler along the
coastal areas. Thursday night may feature more areas of frost
with temperatures dropping into the 30s for much of the area and
lighter winds compared to Wednesday night. This will be
followed by another mainly sunny day for Friday under the
continuing influence of high pressure that will be starting to
shift offshore. This will help cause winds to shift from ENE
early in the day to ESE and then eventually SSE. High
temperatures should be about 5 degrees warmer compared to
Thursday with highs mostly in the low to mid 60s except 50s near
the coast and over the southern Poconos.
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.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Surface high pressure will be over the western Atlantic Friday
night through Saturday as an upper level ridge starts to build
along the east coast. Meanwhile low pressure tracks north and
east into the upper Great Lakes helping pushing a warm front
through PA and upstate NY. This will bring the area a mainly
cloudy day but the chance of showers looks low...only around 15
to 20 percent near the I-95 corridor and 20 to 30 percent over
the Lehigh Valley into the southern Poconos. Highs should be
mainly in the upper 50s to low 60s.

For Saturday night through Sunday, the initial low tracks by
well to to our north over eastern Canada but by later Sunday a
new low will be emerging over the central CONUS. This will help
keep the upper level ridge in place over the east with a
southwest flow at the surface ushering in warmer air. As a
result, expect highs shooting into the mid to upper 70s for most
under variable cloud cover. Right near the coast and over the
Pocono Plateau it will be cooler though with highs mainly in the
upper 60s to low 70s.

By early next week, temperatures have the potential to be even
warmer than Sunday as they may get into the low to mid 80s.
However there will also be an approaching cold front that will
bring chances for some showers and storms beginning as early as
late Monday with better chances for these by Tuesday afternoon
into the early evening.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
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The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas...

Through Today...Mainly VFR. A brief period of MVFR conditions
possible (10%) with some mainly isolated showers. 5% chance of a
thunderstorm across northern terminals. Winds begin
southwesterly around 10 knots and shift to west then northwest
through the day. Gusts of 20-25 knots by the afternoon. High
confidence on mainly VFR conditions.

Tonight...VFR. Winds NW 5-10 kts with gusts up to 20 kts early.
High confidence.

Outlook...

Thursday and Friday...VFR.

Saturday and Sunday...VFR overall.
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.MARINE...
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Winds across the Delaware Bay will subside around daybreak.
Winds diminish across the coastal waters through the morning,
but remain gusty around 20 kts during the afternoon. Seas will
continue to build, however, peaking around 5-7 feet this
afternoon. These likely remain near 5 feet thru tonight, hence
the SCA continues on the ocean zones through tonight.

Outlook...

Thursday...Small Craft Advisory conditions diminishing in the
morning.

Friday through Sunday...The conditions are anticipated to be
below Small Craft Advisory criteria.
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&&

.TIDES/COASTAL FLOODING...
A period of southerly flow will occur into Wednesday morning
ahead of a cold front. This is forecast to result in surge
values rising to 1-2 feet above normal along Delaware Bay, the
tidal Delaware River, and Chesapeake Bay. With the full moon
occurring today, astronomical tides will be maximized around
this time as well. This should result in some areas of minor
coastal flooding with the Wednesday morning high tide. As it
stands currently (Tuesday afternoon), sites in the Delaware Bay
and the Chesapeake will touch minor flooding, but stay below the
threshold to issue an Advisory. PETSS guidance remains
relatively bullish on Tolchester Beach getting near Moderate,
with some guidance suggesting they will not even touch minor at
all. If anywhere were to need an advisory, it would be the
Maryland Eastern Shore, but the forecast suggests that isn`t
necessary at the moment.

Coastal flooding is not currently anticipated along the
Atlantic coast, except for potentially Barnegat Bay.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
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PA...None.
NJ...Freeze Watch from late tonight through Thursday morning for
     NJZ001-007-008.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 7 AM EDT this morning for ANZ430-
     431.
     Small Craft Advisory until 6 AM EDT Thursday for ANZ450>455.
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&&

$$

SYNOPSIS...Fitzsimmons/Gorse/RCM
NEAR TERM...RCM
SHORT TERM...Fitzsimmons
LONG TERM...Fitzsimmons
AVIATION...AKL/Fitzsimmons/Gorse/MJL/RCM
MARINE...AKL/Fitzsimmons/Gorse/MJL/RCM
TIDES/COASTAL FLOODING...