Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 230526
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
120 AM EDT Tue Oct 23 2018

.SYNOPSIS...
High pressure will move off the North Carolina coast tonight.
Canadian high pressure will push a cold front across the coast
Tuesday night. Low pressure will develop along the Gulf Coast
Thursday, bringing good rain chances to the Carolinas Friday
into Saturday.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 1030 PM Monday...Only adjustment with the late evening
update was to bump up sky cover a few notches, as cirrus looks
set to gradually thicken from the west overnight. Potentially
a few lower clouds in weak over-running could form. Latest VWP
from KLTX shows a weak onshore flow in the lowest 2 kft, and
this is likely a little stronger and deeper along the NE SC
coast.

As of 6 PM Monday..Minimal alterations needed to the forecast,
equatorial Pacific cirrus thrust high into the troposphere by
hurricane Willa off the Baja, is just edging into our area but
little impact anticipated to the sensible weather overnight,
only a few fuzzy stars, or a briefly gauzy moon. As the high
slips offshore, a weak return flow will draw clouds toward the
NE SC coast, and current sky grids account for this moisture
advection. Surface winds light to calm and overnight, as the
faint return flow will not budge the colder continental air
densely in place.

As of 3 PM Monday...High pressure drifts farther offshore overnight
into Tue with weak coastal trough poised to develop in the low level
return flow. Surface features and the pattern aloft farther to the
west suggest the trough will remain offshore through the period. In
fact the trough will be pushed farther offshore late in the day by
the approach of a dry cold front. Development of the trough
overnight into Tue will result in northeast flow, especially along
the immediate coast. In addition to northeast flow, a scattered to
broken stratus deck will develop prior to sunrise, likely lingering
over the area into early afternoon. Isentropic lift however remains
offshore, along with deeper moisture, and the region should stay dry
tonight into Tue. Lows will be near climo, mid to upper 40s. Mix of
clouds and sun on Tue, especially closer to the coast will limit
highs slightly, although weak warm advection this evening coupled
with airmass modification will lead to temps near to slightly above
climo, low to mid 70s.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
As of 3 PM Monday...Amplified mid-level pattern continues Tue night
into Wed. Weak shortwave dropping southeast across the KY/TN valleys
will drive a cold front across the area later Tue into Tue night.
Minimal moisture return ahead of the front will keep it`s passage
dry. Winds pick up in the wake of the front, but the cold air lags
the boundary and Tue night lows will end up above climo. High
pressure following the front builds in from the northwest Wed before
shifting over the OH Valley Wed night. Northerly flow will keep
temperatures below climo on Wed despite an abundance of sunshine.
Lows Wed night will be near climo, helped by light northerly winds
preventing strong radiational cooling.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 3 PM Monday...A shortwave will drop across the OH Valley
from the Midwest during Thursday night into Friday. As the
shortwave moves eastward low pressure will move out of the
northeast Gulf of Mexico and intensify as it treks near the
Carolina coast late Friday into Saturday. The low will create
breezy conditions and provide the area with a very good chance
of rainfall. The position of the low just off the coast will
also lock in below normal temperatures. Conditions will improve
during Sunday then another cold front will move across the area
during Monday.

&&

.AVIATION /05Z TUESDAY THROUGH SATURDAY/...
As of 06Z...Generally expecting VFR through the period. The
exception could be some MVFR cigs that develop along the coast early
in the day Tuesday in response to warm advection and weak trough
developing. Winds will stay light and variable unless a sea breeze
manages to develop.

Extended Outlook...VFR through Thur, except for low confidence MVFR
cigs at the coastal terminals Tue night as a cold front moves
through. MVFR/IFR/RA/Windy Fri/Sat morn. MVFR developing Sat
aftn/evng.

&&

.MARINE...
NEAR TERM /THROUGH TUESDAY/...
As of 6 PM Monday...The wave spectrum docile, depicting light
wind-seas from E-ENE every 5 seconds, and weak E swell every 11
seconds, combining, to produce overall seas of around 2 feet.
This to prevail overnight into Tuesday.

As of 3 PM Monday...Surface high moving off the coast this
afternoon will shift farther east overnight and Tue. Weak
coastal trough takes shape tonight and lingers on Tue. Gradient
will remain weak in the vicinity of the trough with easterly
winds backing to northeast. Speeds will remain light through the
period, 10 kt or less. West to northwest flow starts to develop
late in the period as a dry cold front moves into the region.
Seas 2 ft or less will continue through the end of the period.

SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
As of 3 PM Monday...Dry cold front moves across the waters Tue
night but cold advection lags the front until almost daybreak
Wed. Initially offshore flow Tue night is relatively weak,
around 10 kt increasing to 10 to 15 kt after midnight. Strong
north to northeast winds develop right around daybreak Wed with
speeds increasing to a solid 20 kt through Wed morning. Winds
slack off a little Wed afternoon but secondary surge arrives Wed
night, pushing northeast flow close to 20 kt through the end of
the period. Headlines will likely be required, although it may
end up being a SCEC instead of an SCA. Seas around 2 ft Tue
night start building Wed, in response to increasing northerly
flow due to cold advection and pinched gradient. Seas 3 to 5 ft
expected for Wed and Wed night with possibility of 6 ft well
away from shore overnight.

LONG TERM /THURSDAY THROUGH SATURDAY/...
As of 3 PM Monday...High pressure will ridge south across the waters
Thursday. NE-E flow will increase during Friday as an area of low
pressure moves from the northeast Gulf of Mexico to the adjacent
Carolina waters. The low will exit during Friday night into Saturday
allowing the flow to back to a northwesterly direction Saturday. The
flow will weaken during the afternoon Saturday as the pressure gradient
subsides with the passage of the low. A Small Craft Advisory will
likely be required Friday morning through Saturday.

&&

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

&&

$$

SYNOPSIS...ILM
NEAR TERM...III/MJC
SHORT TERM...III
LONG TERM...SRP
AVIATION...MBB


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