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000
FXUS61 KPHI 171839
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
239 PM EDT Wed Apr 17 2024

.SYNOPSIS...
High pressure continues to move offshore as a series of fronts and
low pressure systems begin to affect the East Coast today through
the end of the week. High pressure looks to return for the weekend
and the start of next week.

&&

.NEAR TERM /THROUGH THURSDAY/...
Surface low pressure over the Great Lakes will continue to track to
the north and east tonight. Meanwhile, a warm front extending out
from that low will also continue to lift north through the region
this evening. A secondary low will form over the southern
Appalachians, will pass through Delmarva and southern New Jersey
tonight, then will become nearly stationary offshore through
Thursday.

The first wave of showers is moving through southern New Jersey.
Right around Cape May county, MUCAPE is around 500 J/kg, and there
is some locally heavy rain and perhaps a rumble of thunder. Outside
of that, MUCAPE is minimal, and showers are lighter. These showers
should taper off in the next hour or so.

As the secondary low develops and moves across the southern portions
of the forecast area, and showers will redevelop tonight. There will
be a surge in low level moisture due to increasing onshore flow as
well some some mid-level instability. MUCAPE values will rise back
to as much as 500 to 1000 J/kg, and with a 30 to 40 kt LLJ, some
additional thunderstorms are possible. Will cap thunder at chance
across the region for the overnight period. Not expecting severe
storms out of this, but a brief downpour and some lightning strikes
can be expected.

With the low over the western Atlantic east of the New Jersey shore,
onshore flow will keep rain, drizzle, and fog in the forecast for at
least coastal New Jersey, and into northern New Jersey, and the
eastern Lehigh Valley through Thursday. Elsewhere, it will be a
cloudy and cool day.

Lows tonight will range from the low to mid 40s in the north to the
mid 50s in Delmarva and highs on Thursday will generally be in the
low to mid 50s, though it should be warmer in Delmarva, where it
could get into the lower 70s.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
Overall, the short term forecast remains largely unchanged. By
Thursday night, the weak coastal low will be shunted south and
eastward enough that surface high pressure can build in and briefly
shutoff the chances for showers. Lows Thursday night look to fall
into the 40s most everywhere across the region.

Following the brief respite from showers Thursday night, the next
mid-level wave approaches the region on Friday. Latest guidance
continues to indicate that the pre-existing high will be strong
enough to hold off any precipitation through the morning. However,
the approaching wave will eventually move in and bring yet another
cold front across the region with the opportunity for more showers.
Chances for showers begin to increase Friday afternoon and look to
peak Friday night. However, the front overall continues to look  to
be drier so chances for precip Friday night are now around 30-40
percent at most. Showers look to clear the region by late Friday
night/early Saturday morning. Temperatures will rise into the upper
50s to low 60s during the on Friday before falling into the upper
40s to low 50s Friday night.

High pressure begins to nudge in on Saturday as the cold front moves
offshore. With the exception of some lingering showers in the
morning along the coast, everyone should be dry on Saturday with
gradually clearing skies. Temperatures will get into the mid to
upper 60s.

&&

.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
The back half of the weekend and into early next week looks rather
benign as high pressure continues to settle in on Saturday Night
with the front from Friday stalling to the south of the region. Long
range guidance is continuing to suggest that a system will slide by
just to our south Sunday Night into Monday along the boundary.
Depending on exactly how far south the front stalls, this would
potentially allow a few showers to leak back into the most
southern portion of the region Sunday Night. Most of the
deterministic guidance and ensembles keep the weak area of low
pressure far enough south for everyone to stay dry however, and
no mentionable PoPs are currently in the forecast. High pressure
begins to settle in for Monday/Tuesday with quiet weather
anticipated. Another system looks to come in around mid-week
with some showers, but guidance varies quite a bit beyond
Tuesday.

With the front to the south of the region though, temperatures will
likely be below normal through Monday, with highs in the upper
50s/low 60s and overnight lows in the upper 30s/low 40s.
Temperatures look to moderate for the middle of next week, with a
return to near normal temperatures.


&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas...

Tonight...MVFR by this evening, quickly lowering to IFR/LIFR. SHRA
and BR will develop tonight, and cannot rule out a few TSRA. SHRA
end late, but low CIGs and BR will persist and keep IFR/LIFR conds
across the terminals. E winds 5 to 10 kt. Moderate confidence.

Thursday...IFR in the morning, gradually improving to MVFR in the
afternoon. NE winds 10 to 15 kt. Low confidence.

Outlook...

Thursday Night...Sub-VFR conditions likely (50-70%) with stratus
hanging around.

Friday through Friday Night...Sub-VFR conditions likely (50-70%)
with low clouds through most of Friday and scattered showers moving
in Friday Night. Conditions lift to VFR by late Friday Night as a
cold front comes through.

Saturday through Monday...VFR expected. Potentially gusty winds on
Saturday afternoon.

&&

.MARINE...
Sub-Small Craft Advisory conditions tonight, then onshore flow
increases over the ocean waters on Thursday. A SCA remains in effect
for the northern NJ ocean waters for E-NE winds 15 to 20 kt with
gusts up to 25 kt and 4 to 6 ft seas for Thursday.

VSBY restrictions in fog and showers tonight, and then fog and light
rain and drizzle will persist through Thursday. Cannot rule out a
few thunderstorms tonight as well.

Outlook...

Thursday Night...Small Craft Advisory in effect through Thursday
Night for coastal marine zones north of Cape Henlopen as seas will
be around 5 to 6 feet. No marine headlines on the Delaware Bay or
ANZ455.

Friday...Small Craft Advisory conditions possible (30-40%) for
coastal waters north of Cape Henlopen as seas hover around 5 feet.
No marine headlines expected for the rest of the waters.

Friday Night through Monday...No marine headlines expected.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory from 6 AM Thursday to 6 AM EDT Friday for
     ANZ450-451.
     Small Craft Advisory from 6 PM Thursday to 6 AM EDT Friday for
     ANZ452>454.

&&

$$

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