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182
FXUS61 KPHI 121857
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
257 PM EDT Sun May 12 2024

.SYNOPSIS...
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Low pressure over southeastern Pennsylvania this afternoon will
move offshore this evening. High pressure builds south of the
Mid-Atlantic region tonight into Monday. Another area of low
pressure brings more unsettled weather by the middle of next
week.
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&&

.NEAR TERM /THROUGH MONDAY/...
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Low pressure currently southeastern Pennsylvania has an associated
occluded front southeast into the southern Delmarva. Rain to
the north and east of the boundary is diminishing as the surface
low pivots offshore by this evening. Scattered showers and thunderstorms
over the eastern shore of Maryland will continue east-southeastward
for the rest of the afternoon to be offshore 20Z-22Z. Stronger
cells will contain small hail and wind gusts to 30 knots.

Any shower/thunderstorm activity will quickly wane with the loss
of surface-based instability by early evening. Clouds will diminish
rapidly around 00Z as drier air filters in. Patchy fog will form
overnight with radiational cooling and light winds. Low temps will
be in the 40s.

Quiet weather makes a brief return Monday with partly sunny skies
and temperatures peaking in the lower to mid 70s under broad scale
subsidence.
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&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
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Fair weather will continue Monday night with high pressure
remaining offshore and dry air remaining in place. Seasonable
temperatures continue with lows Monday night in the 50s.

Poor weather will return for Tuesday into Wednesday as low pressure
slowly deepens across the Ohio valley and advances slowly towards
the Middle Atlantic. The low should tap into some moisture across
the Appalachians and it will be carried up over our region. A period
of rains and perhaps a few tstms are expected for the period. Plenty
of likely/categorical pops for Tue night/Wed. Temperatures will be
little above normal Tue, but then get scaled back for Wed with plenty
of clouds and rains around. Highs Wed will mostly be in the mid/upper
60s. Rainfall from the midweek system could range from 1 1/2 inches
for Delmarva and SE NJ to around 1/2 inch for the NW areas.
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&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...

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In the wake of the system from the short term, improving conditions
are set for Wednesday night with only chance pops in the grids for
Wednesday evening. After that, upper ridging and weak surface high
pressure settle across the Middle Atlantic and Northeast. A mild
night is expected with lows in the mid/upper 50s.

A short period of mostly fair weather to end the upcoming week is
foreseen presently. The upper ridge diminishes while high pressure
moves offshore. We can`t rule out a couple isolated showers Thu
afternoon, but pops will only be slight chance for now and won`t
appear in the text products. Seasonable temperatures expected with
highs in the low/mid 70s.

Later Friday and into next weekend look unsettled (again!). A
northern stream upper trough moves across the Great Lakes and tries
to absorb some moisture from the Ohio Valley. We`ll carry some
chance pops for Fri night and Saturday for now and keep lower chance
pops into Sunday. There is enough uncertainty with regards to these
periods for now, so check back in a few days for better details.
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&&

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

This afternoon...Ceilings 1-2K ft over PA/NJ/northern DE
through the rest of the afternoon. Sct-bkn clouds with bases
3-5K ft over southern DE and Eastern shore MD will continue rest
of the day. An area of light rain over NJ will continue through
mid afternoon before dissipating. Scattered showers and
thunderstorms will move through Delmarva this afternoon. SE
winds around 5-10 kt.

Tonight...Any lingering low ceilings will become few-skc
00Z-02Z. Ceilings 1-2K ft form once again after 06Z in
southeast PA, northern Delmarva, and inland NJ with moisture
trapped at low levels and light winds.

Monday...Low clouds and fog burn off 12Z-14Z then VFR.

Outlook...

Monday night through Tuesday...No significant weather expected.

Tuesday Night through Wednesday night...Sub-VFR conditions expected
with occasional showers.

Thursday/Friday...No significant weather expected.
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&&

.MARINE...
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No marine headlines are in effect through Monday. East to Southeast
winds 10 to 15 kts this afternoon will diminish to around 5-10 kts
tonight. South wind around 10 knots Monday. Seas of 3-4 feet. Scattered
rain showers through this afternoon.

Outlook...

Monday night...No marine headlines expected.

Tuesday through Wednesday...SCA conditions possible (30-40%) as
wind gusts get near 25 kt. Significant wave heights approach 6
feet Wednesday. Occasional showers.

Wednesday night and Thursday... SCA seas possible, diminishing
Thu. Showers Wed night then mostly Fair Thursday.
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&&

.TIDES/COASTAL FLOODING...
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High tide has passed over the Atlantic Ocean however trapped water
in the back bays will slowly empty through this afternoon.

Spotty minor flooding is also expected with tomorrow morning`s
high tide within the Chesapeake Bay.

No further tidal flooding issues are expected beyond this
morning`s high tide.
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&&

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

&&

$$

SYNOPSIS...Deal/Franklin
NEAR TERM...Franklin
SHORT TERM...OHara
LONG TERM...OHara
AVIATION...Franklin/OHara
MARINE...Franklin/OHara
TIDES/COASTAL FLOODING...