Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 150800
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
300 AM EST Fri Dec 15 2017

.SYNOPSIS...
Seasonable and fair weather will continue through the weekend,
with a dry cold frontal passage expected late today followed by
high pressure. Southerly winds and a warming trend will begin
Sunday and last through Tuesday evening ahead of a cold front,
with a chance of rain Monday and Tuesday. A cooler and drier air
mass will overspread the area mid-week in wake of the cold
front. Another cold front will approach the coast next Friday,
potentially creating a wet start to next weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 300 AM Friday...Area of low pressure was developing along
weak cold front draped from west to east across the local
forecast area early this morning. This low will deepen slightly
over the Cape Fear coast this morning before lifting off to the
NE into the waters off the Delmarva coast by this evening. Winds
will be variable at times with a more northerly flow to the
north side of front and SW to the south. Overall light to calm
winds this morning will pick up out of the west on the back end
of the wave of low pressure through today. Deep mid to upper
trough extending down from the Great Lakes connects back to
cutoff low over Baja California. Westerly flow aloft will stream
this associated mid to upper level moisture across the
Southeast through today. Sounding data and moisture profiles
show decent layer of moisture at times between 15k and 25k and
therefore expect periods of mid to high clouds to continue to
stream across the area through today. Otherwise not expecting
any pcp from the weak system.

As low lifts off to the northeast, the cold front will push
south and east as high pressure builds in behind it late today
through tonight. The mid to upper trough should also push far
enough south to displace most of the higher clouds away from the
local forecast area. Overall expect sunshine to be filtered out
by mid to high clouds through today with deep westerly
downslope flow. A cool start to the morning will be followed by
a nice warmup with temps reaching near or above 60 degrees. By
tonight skies will clear with some drier and cooler air moving
in behind front. Expect temps to drop down to the low to mid
30s.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
As of 300 AM Friday...Longwave upper pattern not yet established
during this period. Split jet stream with the northern branch
retreating back northward with time and the southern branch
extending northward. During this same time period, an upper ridge
will amplify and begin to affect the local FA by Sunday with the
upper ridge axis extending from the Bahamas north to eastern NC by
the end of this period. At the sfc, center of high pressure will
park itself across the ILM CWA and adjacent waters Sat thru early
Sunday then drift east and offshore by Sunday night. With subsidence
overhead, clouds will basically be non-existent other than thin
jetstream cirrus Sat thru early Sun morning. With the expanding
south to north upper ridge axis across to just east of the FA by the
end of this period, additional clouds will basically begin to
override the ridge axis. Looking at mainly opaque high level clouds
early Sunday and eventually mid-level clouds by Sunday night.
Looking at low clouds expanding across the FA as illustrated by
various model RH Time Height displays for locations across the FA.
Have delayed the arrival of stratiform light rain to the pre-dawn
Monday hrs. As for temps, at or a category below normal temps for
Sat. Decent rad cooling conditions Sat night/Early Sun will drop
lows to around the freezing mark with upper 30s to around 40 for the
immediate coast. Looking at a nice warm-up Sunday with return flow
from the high sliding off the Carolina coasts. Highs will be a good
5 to 10 degrees milder than Sat progged highs with weak WAA
occurring. Sun night will see clouds and threat of pcpn keep lows
elevated, running a good 10 degrees above the norms.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 300 PM Thursday...Primary caption this period, `Milder
with Rain Chances Early Next Week`. Highly amplified troughing
trend in the Baja and SW desert will cause expansion northward
of the the Bahamian/FL upper ridge. Concurrently, surface high
pressure centered offshore of the Carolinas, will help to
complete the noteworthy warm-up, circulating milder air in
southerly flow. Robust moisture advection will ensue as lower
tropospheric winds tap Gulf air. Two time periods encapsulated
by this moisture in deep column lift occur Monday, and again
late Tuesday. Monday a jet-streak entrance region appears
aligned to provide support aloft, with frontal convergence
coming into play Tuesday. The period Monday and Tuesday offer
rain chances, although a high uncertainty prevails on how much.
Drying/cooling Wednesday in wake of the front, but return flow
quick on the heels, by THU night ahead of another approaching
cold front.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
As of 06Z...VFR through the TAF period. Calm winds tonight
across the area as a weak front drops south across the area. A
deep westerly flow will continue to stream some mid to high
clouds across the area through today. Sfc winds will pick up
slightly out of the west by late morning and then will veer to a
more NW direction as front moves farther south and high
pressure builds in behind it by tonight.

Extended Outlook...VFR. Possible MVFR Monday associated with a
low pressure system moving across the Southeast.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 300 AM Friday...Generally quiet marine conditions early
this morning will rebound later today. Low pressure will deepen
as it moves off to the northeast dragging front south and east
of forecast area. Light SW to W winds less than 10 kts will
increase up to 15 to 20 kts briefly as they veer around to the
W to NW this afternoon into early evening as front pushes
south and east. Seas 2 to 4 ft will jump up to 3 to 5 ft for a
brief period toward evening before dropping back down after
midnight as winds shift north and begin to diminish.

SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
As of 300 AM Friday...Marine conditions will be primo for boaters
venturing into the local Atlantic waters. It will be on the cool
side with temps limited by local SSTS in the 50s.
Center of high pressure will be overhead Sat then sliding slowly
east to the offshore waters by Sun night. Variable winds less than
10 kt will occur during Sat followed by return flow around the
departing high providing SE to S 10 kt Sun and SSW 10 to 15 kt Sun
night. Light Rain chances will increase to low chance late Sun
night. Significant seas will subside to less than 2 ft during Sat as
input from locally produced wind waves decreases. This will leave a
dominating 1 to 1.5 foot easterly ground swell at 10 second periods
Sat night thru Sunday. Wind waves will increase Sun night but the
small ground swell will remain dominant.

LONG TERM /SUNDAY THROUGH TUESDAY/...
As of 300 PM Thursday...Marine conditions will gradually worsen
into early next week, as a cold front approaches, then crosses
the coast late Tuesday night or early on Wednesday. Small Craft
Conditions appear to be approached sometime on Tuesday, by
evening, in blustery SW wind of 20 KT and gusty, and 5 foot seas
offshore. Conditions inshore will not be as bad, due to cooler
waters. Rain showers may reduce visibilities at times Monday
through Tuesday night.

&&

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

&&

$$

NEAR TERM...RGZ
SHORT TERM...DCH
LONG TERM...MJC
AVIATION...RGZ



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