Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 180223
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
1023 PM EDT Tue Oct 17 2017

.SYNOPSIS...
Canadian high pressure building into the Mid-Atlantic states
will bring several days of cool, dry weather to the Carolinas.
Temperatures should begin to warm up this weekend as the high
moves off the coast.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
As of 1000 PM Tuesday...Surface high north-northwest of the
region will maintain dry and cool conditions through the period.
In the mid-levels a 5h trough will move off the coast and a weak
shortwave ridge will try to build north. High clouds have
shifted offshore, leaving clear skies overnight. Deep
northerly flow aloft will contribute to an abundance of dry air,
as will subsidence behind the exiting 5h trough and along the
top of the marginal 5h ridge. Low level dry air and boundary
layer winds around 15kt should keep surface mixed enough to
prevent any fog development. Mixing will also limit the
effectiveness of radiational cooling, although overnight lows
will end up around 5 degrees below climo. Inland cold spots will
be right around 40 with locations along the coast near 50. A
slight increase in thicknesses Wed (both low level and
1000-500mb) as the air mass starts to modify, mainly due to
sunny to mostly sunny skies, will result in highs topping out
around climo. Low level convergence off the coast may lead to
some marine clouds and showers, but do not see much cloud
moving onshore, let alone any precipitation.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/...
As of 300 PM Tuesday...High pressure becomes elongated from the
southern Appalachians northeast into the Atlantic waters Wed
eve. This will allow for a greater on shore component to the low
level winds which should give a push to some of the maritime moisture
from the coastal waters associated with a bit of shortwave
energy riding by. This enhanced low level moisture should move
down from the NE Wed eve brushing the coast. Moisture profiles
show a very dry column above 5k ft but a decent shallow layer
below with mainly some strato cu clouds expected overnight Wed
into early Thurs.

By Thurs aftn, the high pressure becomes centered over the
southern Appalachians allowing for a deeper northerly flow,
cutting off the Atlantic moisture and providing a reinforcing
push of dry air. Another minor shortwave passes by Thurs aftn
but the column remains too dry to produce anything more than a
few clouds. Pcp water up near an inch along the coast Wed night
will be down to a half inch by Thurs aftn. Inland remains near a
half inch through the period. Overall, aside from some passing
clouds, expect dry and seasonable weather through the period.

Better radiational cooling Thurs night with lighter winds and
mainly clear skies expected but basically a gradual warming
trend should keep overnight temps roughly the same both
nights...within a few degrees on either side of 50. The high
temp on Thurs should be nearing 80 most places.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
As of 300 PM Tuesday...It will remain high and dry into Sunday
as high pressure remains in control of area weather. An
approaching cold front and return flow around the high will
bring increasing clouds Sunday and Sunday night with a small
chance of showers. Chances for showers will continue Monday and
Tuesday as the front moves into and through the area. Max
temperatures Friday through Monday will be in the upper 70s to
around 80 and in the mid 70s Tuesday. Minimums will moderate
from the low to mid 50s Friday morning to the low to mid 60s
Monday and Tuesday morning.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
As of 00Z...High confidence for VFR conditions through the
forecast period. Winds should stay above 3 kt through the
night. Moisture profiles do not support fog. Wednesday, nearly
clear skies with continued northeast flow, albeit not as strong
as today.

Extended Outlook...Possible MVFR cigs Thurs AM. Possible
showers on Monday. Otherwise VFR.

&&

.MARINE...
NEAR TERM /THROUGH WEDNESDAY/...
As of 1000 PM Tuesday...Northeast winds of 20 to 25 kt with
higher gusts and seas up to 6 ft will necessitate the
continuation of a Small Craft Advisory into at least Wed
afternoon. The exception will be in AMZ254 where the bulk of
the north-northeast winds/swell have been sheltered by land.
The Small Craft Advisory has been downgraded to a Small Craft
Should Exercise Caution for this segment of the coastal waters
where seas will be 4 to 5 ft with wave periods 5 sec or less. It
is also possible that the end time of the SCA may need to be
extended beyond 6 PM EDT Wed. However have low confidence in
this for now and do not plan any adjustments to the headlines.

SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/...
As of 300 PM Tuesday...High pressure will be more elongated from
SW to NE north of the area which will produce a slightly more
easterly component to the wind through Wed night. This NE push
of winds up to 20 kts will continue to produce seas up near or
slightly above SCA thresholds, near 6 ft, through Wed evening.
WNA model shows a decrease in seas to below SCA criteria after
midnight as gradient relaxes slowly into Thurs. Also, the winds
will become more northerly in direction through Thurs which
should help keep strongest winds off shore. Seas 4 to 6 ft
initially will be down to 3 to 5 ft by Thurs aftn and 2 to 4 ft
by Thurs night.

LONG TERM /FRIDAY THROUGH SUNDAY/...
As of 300 PM Tuesday...Northeast winds of 10 to 15 KT Friday will
gradually become easterly by Sunday morning then southeast by Sunday
night.  Seas of 2 to 4 FT Friday will diminish to 2 to 3 FT Saturday
then increase to 3 to 5 FT by Sunday evening.

&&

.TIDES/COASTAL FLOODING...
As of 300 PM Tuesday...Astronomical tides are increasing as we
approach a new moon on Thu. This coupled with strong NE winds,
may breach minor coastal flooding thresholds at Wrightsville
Beach and advisories may be needed along portions of the North
Carolina coast around the time of high tide for the next several
days. The same will be true of the lower Cape Fear River to
include downtown Wilmington.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...Small Craft Advisory until 6 PM EDT Wednesday for AMZ250-252-
     256.

&&

$$

NEAR TERM...RJD
SHORT TERM...RGZ
LONG TERM...RAN
AVIATION...DL
TIDES/COASTAL FLOODING...TRL/RJD



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