-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KILM 201107
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
707 AM EDT Sun Aug 20 2017

.SYNOPSIS...
A stalled front just inland from the coast will weaken and
transition to trof of low pressure by Monday. High pressure
will expand across the area from the western Atlantic Monday
thru Wednesday, continuing the heat and high humidity. A
modest cold front will approach from the northwest late
Wednesday night. Latest weather models progress this cold front
across the area early Thursday, and off the Carolina coasts and
well offshore by late Thursday. Canadian high pressure will
ridge across the area Friday thru Saturday bringing with it a
temporary reprieve from the summer heat and high humidity.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 330 AM Sunday...A dissipating frontal boundary was
lingering just northwest of the forecast area generally
along the 70-degree dewpoint line as of 06Z. There will be
potential for at least patchy fog development southeast of this
boundary towards morning, especially in those areas that
received rainfall Saturday afternoon. This boundary is expected
to push a little further south today, which should limit any
chance for widely scattered showers or tstms this afternoon
primarily to the southern and eastern CWA. As this boundary
isn`t much of a front, the air behind it will remain quite warm,
with highs reaching the mid 90s. Slightly lower dewpoints,
however, will keep heat indices from reaching advisory criteria,
though will see values reach the low 100s. Nocturnal
development over the waters Sunday night may drift north and
impact the coastal zones, so will maintain a low PoP to account
for this possibility.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
As of 330 AM Sunday...Cloudiness and increased potential for
convection will threaten the viewing of the solar eclipse Mon
afternoon. The hier chance for convection and associated
cloudiness will exist across the southern ILM CWA and also
across the coastal counties of the ILM CWA. The western Atlantic
ridging aloft will expand westward across the FA and to the
Gulf Coast states. However, a weak inverted trof aloft
extending from the upper low over the central Gulf of Mexico
early Mon, will weaken as it pushes onshore and inland during
Mon. The dynamics from this feature combined with sfc features
ie. sea breeze and whats left of a stalled front, will result in
clouds and chance for convection. have kept POPs in the low
chance category, mainly as mentioned earlier across the southern
ILM CWA and the immediate coast. Have leaned toward the drier
GFS this period which would support a better viewing chance of
the solar eclipse.

For Monday night thru Tue night, the western Atlantic ridging
across the FA into the northern Gulf of Mexico will help keep a
partial lid on convection across the FA. However, not strong
enough to prevent sea breeze and Piedmont trof induced
convection Tue afternoon and evening. POPs will remain in the
low chance category. Convection ahead of a cold front late Tue
night, will be on the doorsteps of the ILM CWA come daybreak
Wed. As for daily max/min temps this period, both will run
slightly above normal for this time of the year.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 300 PM Saturday...High pressure will reside just off
shore extending down from off the coast of the Mid Atlantic
region on Tues. At the same time a broad ridge aloft on Tues
will be displaced by a trough digging down from the northwest
through mid week. This trough will push a cold front into
the Carolinas on Wed reaching the Eastern Carolinas late Wed
into Thurs and slowly moving off the coast into Fri. The models
show it pushing far south and east to bring drier weather on
Friday into Fri night across the forecast area.

Initially expect moisture convergence along the coast early
Tues along periphery of high with some convection along or off
shore becoming enhanced by sea breeze front Tues aftn. By
Wed, cold front reaches into the Carolinas with gradient
tightening ahead of it with moisture pooling over the Eastern
Carolinas and dynamics aloft on the increase. Pcp water values
will be above 2 inches with convection on the increase ahead of
the front as it drops southeast into the area Wed night into
Thurs. Drier air with lower temps expected by weeks end as
front moves off the coast by Fri. Looks like we may even see a
decent northeast surge behind front by late Fri. As it looks
now, inland should begin to dry out Thurs night with moisture
slow to leave the coast on Fri.

Temps will start out warm into mid week ahead of the front,
near 90, but will drop off to the mid 80s Thurs into Fri as
front pushes south and east.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --
As of 12Z...IFR/LIFR conditions inland terminals thru 13-14z due
to FG and VV. Coastal terminals will see MVFR from BR thru 13Z.
All terminals from 14Z thru this aftn and evening will see VFR
conditions. Will see diurnal Cu develop by late morning and
persist into the evening in the 3.5K to 5.0K foot levels. Did
not include any TSRA with convection coverage overall being
isolated. If anywhere, the sea breeze or the dissipating
stalled front just inland from the coast could provide the lift
for isolated storms. Synoptic Winds generally start out from
the ENE 5 kt and veer this aftn and evening to the SE-S 5 to 10
kt, except around 10 kt across the coastal terminals due to the
aid of the sea breeze or in this case, the resultant wind
boundary. Winds will quickly lower after sunset with most
terminals becoming calm by midnight thru the predawn Mon hrs.
Fog, possibly dense inland, will again make an appearance across
all terminals after 06Z.

Extended Outlook...Increasing coverage of showers/tstms by Tue
through Wed. Flight restrictions will also be possible each
early morning due to stratus/fog Wed.
-- End Changed Discussion --

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 330 AM Sunday...Bermuda high offshore will result in
southwesterly flow around 10 kt across the waters this
morning, but the approach of a dissipating frontal boundary may
introduce some variability in the wind direction by midday. The
gradient will be weak, and speeds are expected to remain around
10 kt through the period, supporting wave heights of around 2
ft. The exact location of the boundary will be difficult to
forecast, and if it slips far enough south, some areas within
the nearshore waters will experience a brief period of
northeasterly winds. Isolated to scattered showers and
thunderstorms will also be possible over the waters, mainly
this evening and overnight.

SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
As of 330 AM Sunday...Sfc ridging will extend across the local
waters from the Western Atlantic high during this period. At the
start of this period, the ridge axis will extend inland north of
the local waters. This will result in E to SE wind directions
during Mon. The sfc ridge axis will drop southward across the
local waters Mon night and Tue, and by Tue night, this ridge
axis will be south of the local waters, extending inland
vicinity of Georgia and northern Florida. This will result in
veering wind directions, becoming south Mon night into Tue, and
SW Tue night. The sfc pg will remain relaxed Mon thru early Tue
with wind speeds 5 to 10 kts. The sfc pg will be in a tightening
phase late Tue thru Tue night ahead of an approaching cold
front. This will yield windspeeds in the 10 to 15 kt range.
Significant seas will initially commence around 2 ft Mon thru
early Tue and increase to 2 to 4 ft late Tue thru Tue night. An
ESE, 1 to 2 foot ground swell at 7 to 8 second periods will
initially dominate the seas spectrum. Wavewatch3 and Swan models
indicate this dominating swell will increase to 2 to possibly 3
feet with periods also increasing to 9 to 10 seconds Tue thru
Tue night.

LONG TERM /TUESDAY THROUGH THURSDAY/...
As of 300 PM Saturday...Southerly winds around high pressure
extending down from off the Mid Atlantic coast will become
more SE Tues aftn in sea breeze but will remain basically 10
kts or less. Winds will begin to veer and increase out of the
southwest Tues night into Wed as a cold front makes its way into
the Carolinas tightening the overall pressure gradient. This
front will make it into the Eastern Carolinas Wed night into
Thurs with stiff SW winds continuing ahead of it. The winds will
begin to veer late Thurs into Fri as the front makes its way
into and through the waters. Shower and thunderstorm activity
will be on the rise ahead of the front through mid week.

&&

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

&&

$$
SYNOPSIS...DCH
NEAR TERM...CRM
SHORT TERM...DCH
LONG TERM...RGZ
AVIATION...DCH