Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 211933
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
333 PM EDT Fri Sep 21 2018

.SYNOPSIS...
High pressure will prevail through early next week. A cold
front will approach the coast late Sunday into early Monday,
but no significant rainfall is expected. An upper trough slowly
approaching from the west, will bring a chance of showers in
the upcoming week. A cold front will reach the coast late next
week.

&&

.NEAR TERM /THROUGH SATURDAY/...
As of 333 PM Friday..High pressure at the surface and aloft
will keep skies clear through the overnight period. The light
winds that result paired with the recent rainfall will set the
stage for widespread fog that will probably become dense across
a significant area that a Dense Fog Advisory will be needed.
Nighttime lows should dip into the mid 60s/upper 60s beaches.
Though the ridging will be moving offshore at all levels heading
into Saturday forecast soundings still show far too much dry
air for precipitation with 20C dewpoint depressions not uncommon
above 5kft.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 333 PM Friday...Surface and mid-level ridging will keep a
weak  front stalled north and west of the area through the
period. The mid- level ridge does start to weaken on Sun which
could allow afternoon convection along the sea breeze and the
Piedmont trough. Coverage will be rather limited given an
overall lack of moisture with precipitable water struggling to
reach 1.5 inches Sun. However, given heating and weak low level
convergence cannot rule out isolated convection. Lack of mid-
level forcing support will keep coverage limited to slight
chance range across the forecast area. Temperatures will
continue to run above climo with highs in the mid to upper 80s
and lows in mid to upper 60s.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
As of 333 PM Friday...Agreement looks above average in GFS and
ECMWF depictions of the H5 field, in the upcoming work week,
anchoring an upper ridge into the area from offshore through
early next week. The ridge to gradually give way, to impingement
of an upper trough from the west middle to late of next week. As
a vigorous short-wave rounds this trough into Friday, a cold
front will be forced to the coast, where it may stall, or lift
north as a warm front, as the short-wave ejects off to the NE,
leaving the front nearly parallel to the coast. Sensible weather
therefor should see isolated to scattered convection this week,
becoming more unsettled late in the week, mainly by the coast.
Because of ridging and mainly pre-frontal conditions, temps to
run a little bit above normal for late September. Interestingly
enough, the low-level vorticity of Florence this period, looks
to approach our coast as a weak tropical low pressure system
later Tuesday, very weak.

&&

.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
As of 18Z...VFR, clear skies and light winds through remainder
of the daytime and first part of the overnight hours. With these
conditions continuing overnight and given the massive amounts
of rainfall the area has received the stage appears set for an
IFR or lower/worse category fog night. Have trended the forecast
in the more pessimistic direction. Not sure why guidance is
sparing MYR in relation to other terminals, even the very
proximal CRE. Back to VFR and clear skies soon after sunrise
Saturday.

Extended Outlook...Mostly VFR through this period. However,
flight restrictions are possible in late night/early morning
fog/stratus each day. And brief flight restrictions are possible
within showers/thunderstorms Sunday through Tuesday, especially
during the afternoon/evening hours.

&&

.MARINE...
NEAR TERM /THROUGH SATURDAY/...
As of 333 PM Friday...Wind and seas minimal with surface high
pressure moving overnight tonight and just offshore tomorrow.
The latter will be responsible for veering flow as speeds stay
capped at 10kt. With only negligible swell energy and diminutive
wind waves all forecast zones will be carrying seas of 2 ft.

SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 333 PM Friday...Elongated surface high off the coast will
gradually retreat east through the period. Gradient will remain
weak with northeast flow peaking on the low side of the 10 to
15 kt range late in the period. Seas around 2 ft Sat night into
Sun may build to 2 to 3 ft due to prolonged period of weak
northeast flow.

LONG TERM /MONDAY THROUGH WEDNESDAY/...
As of 333 PM Friday...Increasingly rough this period, because
easterly wind flow is on the increase, persistent. 3-4 foot
seas to become common with 5 ft waves outer waters into mid
week, generally dominant wave periods of 6-8 seconds. Scattered
marine showers and isolated TSTMS can be expected this period.
A tropical low may approach the coast Tuesday night and weaken.

&&

.TIDES/COASTAL FLOODING...
As of 333 PM Friday...Coastal Flood Warnings will be needed for
the  next several days of high tides along the Cape Fear River
at downtown Wilmington as the freshwater flood wave travels down
the river and increasing astronomical tides associated with the
nearing full moon (Sep 24/25) push up the river. Soon after the
full moon the flooding may drop to advisory levels for the days
that follow as both the flood wave and astronomical effects
abate.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...Coastal Flood Warning until midnight EDT tonight for
NCZ107.
MARINE...None.

&&

$$

SYNOPSIS...MJC
NEAR TERM...MBB
SHORT TERM...III
LONG TERM...MJC
AVIATION...MBB
TIDES/COASTAL FLOODING...MBB


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