708
FXUS61 KPHI 121728
AFDPHI

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

.SYNOPSIS...
Low pressure over southeastern Pennsylvania early 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.

&&

.NEAR TERM /THROUGH MONDAY/...
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.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
The brief reprieve ends shortly though as the ridge breaks down
ahead of an advance cutoff low pressure system moving through
the Ohio Valley region. With a modest surge of PVA and height
falls, there should be ample lift to support fairly widespread
showers across the region Tuesday afternoon through Wednesday.
Severe progs aren`t very supportive so we should be looking at
more of the typical spring/summer showers with maybe a rumble of
thunder and brief periods of moderate rainfall. PW isn`t
forecast to be high with respect to climo as the EFI is
remarkable average for the week across the forecast region.
Ensemble guidance suggests about a 40% of seeing 0.4" or more
with only a 15-20% chance of more than an inch. With rivers back
towards normal streamflows and the rainfall not expected to
fall over a short period of time, there are currently no
flooding concerns.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
Heading towards the end of the week the forecast will be highly
dependent on how quickly the low pressure system through the
middle of the week departs. There`s considerable spread in
guidance clusters from the ensemble suites this morning mostly
dependent on timing. So the forecast is subject to change
somewhat dramatically over the next few days until guidance
becomes more consistent. Eventually another system will bring
widely scattered showers but for the given reason just
mentioned, confidence isn`t sufficiently high on whether that is
Sat or Sun. Thus the forecast call for low to moderate changes
(30-40%) both days with slightly higher chances on Saturday.

Temps through the long term should be fairly seasonable in the
low to mid 70s with overnight lows in the 50s most days.

&&

.AVIATION /17Z SUNDAY THROUGH THURSDAY/...
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 loe 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...No significant weather expected.

&&

.MARINE...
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...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.

&&

.TIDES/COASTAL FLOODING...
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.

&&

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

&&

$$

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