269
FXUS61 KPHI 091036
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
636 AM EDT Thu May 9 2024

.SYNOPSIS...
Several waves of low pressure affect the region with the
unsettled patterned continuing from today through Sunday. High
pressure builds south of the Mid-Atlantic region Sunday night
into Monday. More unsettled weather could impact our area
Tuesday night into Wednesday as a storm system approaches the
area.

&&

.NEAR TERM /THROUGH FRIDAY/...
630 AM...No major forecast changes with this update. A complex
weather pattern continues to unfold across the eastern U.S.
this morning. An initial area of low pressure is moving out to
sea east of New England with its trailing cold front having
pushed into southern Delmarva. This front then extends back to
the west to the next area of low pressure over Illinois. Showers
and thunderstorms are ongoing near and ahead of this next low
and are affecting areas to our south and west into the Carolinas
and Virginia.

As we go into the day today, low pressure tracks east to
east-southeastward toward Virginia with some showers starting
to move into the area by around the late morning to early
afternoon time frame and then continuing off and on for the
remainder of the day. These showers will be associated with the
remnants of the convection currently ongoing to our south and
west. Given that the forecast track of the low has shifted
southward, this will limit the threat of severe weather over our
area as the front will remain hung up near Delmarva. It`s still
possible a few stronger storms could affect Delmarva this
afternoon into this evening but even here it looks like any
instability will be mainly elevated tending to limit the threat.
Farther north over eastern PA into adjacent portion of NJ,
there may not even be any thunder due to lack of instability.
The clouds and showers will keep it much cooler today with east
to northeast winds north of the front. Generally expect highs in
the upper 60s to low 70s with low to mid 60s right near the
coast and over the southern Poconos.

As we go into tonight, rain/showers should actually become more
widespread and steadier as the upper level trough that`s been
driving this unsettled weather shifts eastward towards the coast
increasing PVA over the mid Atlantic. This will result in the
surface low tending to get hung up just south and east of DE
helping keep the rain/showers going. There could be some
embedded thunder but mainly over Delmarva. The precipitation
may also be moderate to occasionally heavy although we don`t
expect there to be much in the way of hydro concerns. Overnight
lows range from mid 40s north to low/mid 50s south.

Friday is definitely shaping up to be quite unsettled and cool
with periods of rain continuing as the upper level trough will
be very slow to translate eastward through the area. This will
keep a surface trough over the mid Atlantic even as the center
of low pressure starts to track out to sea. Brisk winds out of
the east/northeast will add to the rawness of the day with most
areas seeing highs only in the low to mid 50s and the southern
Poconos likely not getting out of the 40s.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
Unsettled weather will continue for the Friday night through the
Saturday night time frame though a brief respite from the shower
chances will occur during the early part of Saturday. PoPs
remain in the 35-45 percent range Friday night as the low
continues to move offshore but by early Saturday, the low looks
to be far enough away that conditions should be mostly dry
regionwide. Lows Friday night will be mainly in the mid-upper
40s and highs Saturday will warm back into the low 60s.

By later in the day Saturday though, the next wave of low
pressure will arrive out of the Great Lakes, increasing chances
for showers, particularly northwest of the I-95 urban corridor.
Showers continue to move into the region Saturday night (PoPs
45-55 percent) with lows again in the mid-upper 40s.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Unsettled weather continues to end the weekend with showers
possible into Sunday. The low tracking across the region will
begin to push offshore early Sunday but showers may continue to
linger for much of the day.

A brief period of dry weather is expected later Sunday and
Sunday night, and continuing into Monday as high pressure
briefly builds to the south of the Mid Atlantic region. This dry
weather will only be brief as chances will begin to increase
Tuesday night into Wednesday as a storm system approaches from
the southwest.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas...

Today..Mostly cloudy with cigs lowering with time and some
showers moving in by afternoon. However it should stay VFR
throughout the day with lower cigs at MVFR levels holding off
until this evening. Winds generally east to northeast around 5
to 10 knots. Moderate confidence.

Tonight...Rain/showers becoming heavier and steadier with some
patchy fog likely as well. Cigs lowering to MVFR through the
evening with IFR cigs likely overnight. East winds around 10
knots. Moderate confidence.

Friday...Rain/showers continuing with conditions remaining IFR
likely through at least the first half of the day with some
improvement to low MVFR possible by afternoon. East to
northeast winds around 10 knots with some gusts to 15-20 knots.
Moderate confidence.

Outlook...

Friday night-Sunday...Sub-VFR conditions probable (50-60 percent
chance) at times through the period with chances (40-50 percent) for
showers.

Sunday night-Monday...VFR conditions expected.

&&

.MARINE...
Conditions will remain below Small Craft Advisory levels
through today though expect some showers moving in over the
waters by this afternoon.

Rain/showers become more widespread over the waters tonight
with winds and seas starting to ramp up from north to south. A
Small Craft Advisory begins overnight for our northern ocean
zones with these conditions spreading into our southern ocean
zones off the coast of southern NJ and DE Friday morning. The
conditions should remain sub SCA over the Delaware Bay.

Outlook...

Friday night...Small Craft Advisory in effect for Atlantic Ocean
coastal waters. Seas of 5-6 feet expected with winds gusting 20-25
knots. Sub-SCA conditions on the Delaware Bay.

Saturday through Monday...Overall, mainly sub-SCA conditions
expected through the period though seas may linger around 5 feet
during the day on Saturday.

&&

.TIDES/COASTAL FLOODING...
The new moon occurred Tuesday, May 7th, and this is resulting
in high astronomical tides. As a front settles to our south, an
onshore flow will develop and strengthen some through the end
of the week, peaking Friday into Friday night. While the
astronomical tides will be gradually lowering as we get farther
away from the new moon, the onshore flow should boost the surge
at least some. With this combination, widespread minor tidal
flooding is again expected with the high tide tonight into
early Friday morning for the Atlantic coastal zones, the
Delaware Bay, and the tidal Delaware River. As a result, another
round of Coastal Flood Advisories have been issued for these
areas.

With the peak onshore flow leading up to the Friday night high
tide cycle, guidance continues to show moderate tidal flooding
for portions of the coastal areas in the southern half of the
region with this high tide cycle. The most likely locations to
see moderate coastal flooding will be along the coasts in
Atlantic, Cape May, and Cumberland counties in New Jersey, and
Kent and Sussex counties in Delaware. Given that there is still
some uncertainty, opted to go with a Coastal Flood Watch for
these areas and further examination will be needed to determine
if these areas will need to be upgraded to a warning or to an
advisory for Friday night.

The Friday night high tide cycle looks to be the peak of the
coastal flooding potential but additional minor coastal flooding
is forecast with the evening/overnight high tide Saturday night
into early Sunday.

Flooding is not expected at this time for our Maryland zones
along the Chesapeake.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Coastal Flood Advisory from 1 AM to 6 AM EDT Friday for PAZ070-
     071-106.
NJ...Coastal Flood Advisory from 11 PM this evening to 3 AM EDT
     Friday for NJZ016.
     Coastal Flood Advisory from 8 PM this evening to 2 AM EDT
     Friday for NJZ012>014-020>027.
     Coastal Flood Watch from Friday evening through late Friday
     night for NJZ021>025.
     Coastal Flood Advisory from 1 AM to 6 AM EDT Friday for
     NJZ017>019.
DE...Coastal Flood Advisory from 11 PM this evening to 3 AM EDT
     Friday for DEZ001.
     Coastal Flood Advisory from 8 PM this evening to 2 AM EDT
     Friday for DEZ002>004.
     Coastal Flood Watch from Friday evening through late Friday
     night for DEZ002>004.
MD...None.
MARINE...Small Craft Advisory from 2 AM Friday to 6 AM EDT Saturday for
     ANZ450-451.
     Small Craft Advisory from 6 AM Friday to 6 AM EDT Saturday for
     ANZ452-453.
     Small Craft Advisory from 11 AM Friday to 6 AM EDT Saturday
     for ANZ454-455.

&&

$$

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