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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KPHI 080916
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
416 AM EST Fri Dec 8 2023

.SYNOPSIS...
The center of high pressure will slide to our south through
Saturday. A warm front lifts across our region Saturday night
into Sunday, followed by a potent cold front sweeping through
Sunday night. High pressure builds in later Monday and continues
into the middle of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
Mid-level cloud coverage has continued to persist through the
overnight hours across northeast Pennsylvania and northern New
Jersey even as flow has backed more westerly with moisture
trapped under a warm advection driven inversion. Still expect
the clouds to scatter by mid morning, though a shield of cirrus
streaming in from the west will replace them. There is a chance
(~30%) for some patchy fog development with lingering boundary
layer moisture due to earlier snowfall and crossover
temperatures being close to achieved, but it should be confined
closer to river valleys and moisture sources.

Heights will rise today and the column will warm as thicknesses
increase with an upper ridge axis sliding overhead. High
pressure off to the south will gradually slide offshore and
provide a light south/southeast gradient wind today. Filtered
sunshine through the high clouds for the first half of the day
will give way to mostly sunny skies this afternoon, and coupled
with warm advection in the southerly flow, high temperatures
will be 8-10 degrees warmer than Thursday in the low to mid 50s.

Continuing warm advection and increased moisture will lead to a
slightly warmer night than Thursday night with lows in the low
to mid 30s. Dew point depressions will be quite small, and with
wind going light to calm, some patchy fog is again possible. The
wrench in that part of the forecast will be increasing cloud
cover for the second half of the night that may put a halt to
otherwise efficient radiational cooling conditions.
-- End Changed Discussion --

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
-- Changed Discussion --
Guidance indicates a coastal front will start developing over
the region by early Saturday, with cool, moist air mass stalling
over much of the CWA with warmer air riding over it on the south
to southeast flow. This likely results in low clouds and perhaps
some patchy fog or mist/drizzle early Saturday. Some of this may
break as the day progresses, especially across the Delmarva and
southern NJ where the front may creep northward, but near and
north of the I-95 corridor clouds may hang tough and temps will
struggle. Thus, not expecting much rise compared to today, with
temps mostly near 50, but southern locales where the front lifts
north may rise 5-10 more degrees.

Strong trough and cold front will begin to influence the weather
more noticeably Saturday night, with increasing high and mid
clouds. The warm front will still be struggling to lift north,
so cooler temps prevail, but we will stay above freezing at
least, with 30s north and 40s elsewhere. Some patchy
fog/drizzle/mist may again develop late Saturday night.

Sunday, the warm front is finally sent well north of the region
as the southerly low-level jet ahead of the approaching cold
front strengthens rapidly. This will bring southerly winds which
may gust 30-40 mph along with increasing coverage of showers and
possibly even some embedded thunderstorms. The forcing with the
upper trough is quite potent and moist flow significant, so
locally heavy rain may start overspreading the area. The
southerly flow should bring plenty of warmer air northward as
well, so temps surge into the 60s for most.

However, the most active weather likely waits until after
nightfall Sunday night. Southerly winds may gust up to 50 mph
along the coast, maybe even a little higher, thanks to the
extremely powerful low-level jet. Any stronger cells could even
mix down winds up to severe limits. The heaviest rainfall also
will occur as the forcing maxes out just ahead of the
approaching cold front, with totals likely exceeding 2 inches
across much of the area, with localized flooding being a concern
along with perhaps some stream/small river flooding in the
coming days. A strong push of wind may then occur as the cold
front blasts across the region overnight, with widespread wind
advisory gusts possible and perhaps some localized gusts near
severe limits with the front. Temps likely stay in the 50s to
low 60s until the front passes, then rapidly drop into the
40s. A quick changeover to snow with modest accumulation is
possible late in the Poconos.
-- End Changed Discussion --

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
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Storm system will rapidly pull away on Monday, with lingering
breezy conditions and showers possible in the morning, then
increasing sunshine by afternoon. Temps will remain cool, in the
40s.

The remainder of next week looks quite quiet as Canadian high
pressure dominates. Temps will be slightly below normal, with
highs in the 40s and lows in the 20s to low 30s, and there is
little to no chance of any precipitation Tuesday through
Thursday.
-- End Changed Discussion --

&&

.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
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The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas...

Today...VFR ceilings between about 4-6kft affecting KRDG/KABE
have continued to persist overnight but should scatter this
morning. High clouds have moved in and will continue through the
early afternoon. There is a chance (~30%) for some fog
development with lingering boundary layer moisture due to
earlier snowfall and crossover temperatures being close to
achieved, but it should be confined closer to river valleys and
moisture sources. Light and variable wind this morning becoming
southeasterly at 5-8 knots. Low confidence in fog development,
high confidence otherwise.

Tonight...VFR with some scattered high level clouds. Wind
becoming light and variable to calm. High confidence.

Outlook...
Saturday...Sub-VFR possible with low clouds and patchy fog
especially early. Winds southerly 5-10 kts. Low confidence.

Sunday...Sub-VFR likely with low clouds and patchy fog possible
early and widespread rain by late afternoon, with intervals of
IFR likely. Southerly winds 5-10 kts increase to 20-30 kts with
gusts possibly up to 40 kts late. Low confidence.

Monday...VFR conditions likely return later in the day if not
sooner. Winds west-northwesterly around 20 kts with gusts to 35
kts. Moderate confidence.

Tuesday...VFR likely. Winds westerly around 10 kts. High
confidence.

Wednesday...VFR likely. Winds westerly around 10 kts. High
confidence.
-- End Changed Discussion --

&&

.MARINE...
-- Changed Discussion --
No marine headlines expected through tonight. South-
southeasterly wind 5-10 knots. Fair weather. Seas 2-3 feet.

Outlook...
No marine headlines expected through Saturday night. Winds
south-southwest 10-15 kts with gusts to 20 kts. Seas 2-3 feet.

Southerly winds increase through the day Sunday with sustained
winds of 25-30 kts by late afternoon along with gusts reaching
gale force late. Waves building to 5-9 ft.

Southerly winds peak at 35-40 kts with gusts possibly reaching
storm force Sunday night before cold front passes, then winds
swing around to westerly late and drop off to 25- 30 kts with
gusts dropping back to low-end gales. Seas may reach 12 ft
briefly, and a line of squalls may also cross the waters during
the night.

Westerly winds 20-25 kts on Monday with gusts near gale force
early, dropping off slowly as the day progresses. Waves
diminishing to 5-9 ft.

Small Craft Advisory conditions may linger Tuesday with
westerly winds around 15 kts with gusts to 25 kts and waves up
to 5 ft.

Sub-Small Craft Advisory conditions likely return Wednesday with
westerly winds around 15 kts and gusts to 20 kts with waves 2-4
ft.
-- End Changed Discussion --

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...None.

&&

$$

SYNOPSIS...Brudy/RCM
NEAR TERM...Brudy
SHORT TERM...RCM
LONG TERM...RCM
AVIATION...Brudy/RCM
MARINE...Brudy/RCM