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000
FXUS62 KILM 210608
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
208 AM EDT Mon Aug 21 2017

.SYNOPSIS...
A weak front will slowly dissipate across the area through
tonight. Moisture from a trough to our south will make its way
on shore over the southeast coast through Monday. High pressure
will expand across the area from the western Atlantic Monday
thru Wednesday, continuing the heat and high humidity. A cold
front will move across the Eastern Carolinas from the northwest
late Wednesday night into Thursday. Canadian high pressure will
build down behind front bringing drier weather for the weekend.

&&

.NEAR TERM /THROUGH TODAY/...
As of 7 PM Sunday...One last lonely shower is moving SW across
Horry county as a combined sea-breeze/outflow boundry moves
swiftly inland. Expect not much more than this for the remainder
of the night as far as precip goes. Still expecting substantial
fog development overnight throughout the forecast area but
latest indications are that it will not be dense and widespread
enough to warrant an advisory. Have updated gridded database
and forecast to reflect precip trends and refine fog
expectations. Previous discussion follows:

GFS/NAM diverge with moisture profiles during Monday and
specifically during the eclipse with the NAM probably too
agressive with deeper moisture return during the day. Expect to
see the most clouds along SC coastal areas with partly to mostly
cloudy skies, and partly cloudy skies elsewhere once the
stratus/fog dissipates. Focused highest POPs across the southern
areas as well during tomorrow (30-35%) with slight chance to
low chance POPs across remaining areas. Lows are expected to
range from the lower 70s inland to the mid 70s at the coast. As
a result of the disparity in the cloud cover during Monday favor
a blend toward the warmer/less cloudy GFS MAV high
temperatures.

Latest ETSS for downtown Wilmington has predicted levels right
at minor coastal flood thresholds with high tide this evening.
In the absence of heavy rainfall and a fetch that would push
levels above criteria will hold off on a Coastal Flood Advisory
at this time. Subsequent high tides with during the next couple
evenings should exceed thresholds as a result of the new moon.

&&

.SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/...
As of 300 PM Sunday...Ridging aloft to the west will combine
with Atlantic ridge, to produce center of ridge aligning right
over the southeast Mon night through Tues. This will allow for
increased subsidence and dry air aloft which should limit
convection, but shallow tropical moisture will continue to be
present in a S-SE low level wind flow. Essentially, a tropical
airmass will be present with pcp water values up near 1.75 to 2
inches. Overall expect localized cu and convective development
mainly along sea breeze pushing inland through the afternoon and
some convection mainly off shore overnight. The NAM and GFS
were both trying to show a piece of energy rotating around the
ridge from the south possibly producing some clouds or slight
chc of shwrs toward daybreak Wed, but overall not expecting much
coverage through the period.

Temps will be on the warm side with 90 to 95 most places during
the day and in 70s at night.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 3 PM Sunday...Primary feature influencing extended
forecasts is cold frontal passage late Wednesday and early
Thursday. This is supported by GFS/ECMWF upper patterns, both of
which also migrate Canadian High pressure into the region
Friday through the weekend, imparting a slightly drier and
cooler feel than late. GOES-16 shows the circulation near 20N
north of Puerto Rico, which may fester off the FL coast near a
stalled boundary early next week, potentially deepening.
Regardless of intensity, the expectation is this feature will
lift to the north slowly, remaining offshore of our coast. A few
strong storms are possible late Wednesday as wind shear aloft
and low- level convergence increase as the upper trough edges
in. Wednesday may very well be the warmest day of the extended
period, prior to Canadian high pressure intrusion.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
As of 06Z...Conditions favorable for fog development again
towards daybreak, as moisture profiles remain largely unchanged,
and winds in the lowest few thousand feet remain light. Expect
IFR visibilities to develop after 09Z with periods of LIFR
possible. Widely scattered showers and thunderstorms are
expected to develop along the sea breeze and remnant front
across NE SC by midday.

Extended Outlook...Diurnal showers/tstms expected Wednesday
afternoon, becoming more numerous Wednesday night and Thursday
with fropa. Convective potential will decrease Friday as the
front moves south of the area.

&&

.MARINE...
NEAR TERM /THROUGH MONDAY/...
As of 7 PM Sunday...Very light winds with seas of around 2 ft
continue over the waters. Have tweaked winds a bit for the
overnight hours to reflect a sometimes variable direction with a
dissipating front wavering overhead. Previous discussion
follows:

Light onshore flow prevails in a weak pressure gradient so far
this afternoon. The flow is expected to veer to a southerly
direction later in the day and southwest this evening. A weak
surge may briefly build down the coast early Monday morning,
then quickly veer to the southeast and south during the day as
the sea breeze takes hold and the old front washes out. Seas
will average 2-3 ft through the period. Widely scattered showers
and tstms are possible late tonight, and they could get closer
to the Long Bay inshore waters during the morning before the
diurnal shift occurs.

SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 300 PM Sunday...Atlantic high pressure will produce a
southerly flow through the period. As it builds in, it will veer
around from SE to S. A trough will move east Tues night into
early Wed helping to push winds around to the S-SW and increase
slightly. Overall winds will be 10 kts or less through early
Tues with an increase up to 10 to 15 kts late Tues into Tues
night. Seas around 2 ft Mon through early Tue will increase to 2
to 4 ft late Tue into Tue night. A longer period swell up to 10
seconds will mix in with wind waves Tues through Tues night.

LONG TERM /WEDNESDAY THROUGH FRIDAY/...
As of 300 PM Sunday...The extended marine period will become a
bit bumpy ahead of a cold front Wednesday, as SW winds gust to
20 KT and higher Wednesday afternoon. A wind shift will migrate
across the 0- 20 NM waters early Thursday. Strong Canadian high
pressure will interact with the front offshore to produce NE
winds 15-20 KT Thursday into Friday. As a result, `Caution` and
even `Advisory` headlines are possible this period. Seas of 3-5
feet can be expected Wednesday afternoon through much of Friday
before subsiding, and up to 6 feet well offshore. A few storms
may be strong Wednesday night through Thursday as a cold front
crosses the waters and radar updates are encouraged.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.

&&

$$
SYNOPSIS...
NEAR TERM...REK/SRP
SHORT TERM...RGZ
LONG TERM...MJC
AVIATION...CRM
MARINE...MJC/REK/RGZ/SRP