Area Forecast Discussion
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FXUS62 KILM 080929
Area Forecast Discussion
National Weather Service Wilmington NC
429 AM EST Thu Dec 8 2016
High pressure will bring a dry and seasonable day today. A cold
front will move through later on Thursday, ushering in the
coldest temperatures of the season for the first part of the
weekend. A warming trend will follow Sunday into Monday ahead of
the next cold front. Expect seasonable and dry weather Tuesday
as high pressure builds in behind front. Another frontal system
will affect the area during the middle of next week.
.NEAR TERM /THROUGH TONIGHT/...
As of 330 AM Thursday...Areas of stratus early this morning has
prevented fog from becoming an issue. However, A few pockets of
clear skies earlier across Horry County allowed fog to develop
across the Myrtles. If the clear skies prevailed a bit longer,
the fog would have likely reached dense thresholds. For now,
will keep the fog low key.
During daytime morning, will see the sfc based inversion break
allowing mixing to occur resulting in drier air able to break
down the low stratus. Will see insolation later this morning,
however clouds ahead of the approaching cold front will fill
back in as it approaches the FA from the northwest. Only minimal
convergence along the front which is likely not enough for
pcpn development. In fact, with westerly flow aloft, moisture
accompanying this front will scour-some as it progresses to and
across the FA this aftn. Looking at mid-late aftn when the cold
front clears the ILM CWA Coast. The sfc pg will tighten after
the CFP resulting in NW winds increasing. the cold surge lags
slightly behind the front and will really begin to be realized
during the pre-dawn Fri hours. Post frontal clouds will affect
the FA overnight, with the drier air thru the atm column
occurring during Friday, after the mid-level trof axis pushes
thru. Used the hier max temps from the avbl model mos guidance
and also stayed on the hier side for tonights mins which will
occur around or after daybreak due to CAA infiltrating the FA.
.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
As of 300 PM Wednesday...Overwhelming headline for the THU/FRI
period is `Old Man Winter Dips His Toes into the Carolinas`, as
the leading edge of a bubble of Arctic born air infiltrates late
on Thursday. Widespread sub-freezing 20s will greet SE NC and
NE SC daybreak Saturday as this high settles nearly overhead.
Even with cold air advection breezes Thursday night, temps well
inland may fall below freezing. A brief deepening of column
moisture Thursday into the afternoon could provoke or motivate
a few showers to form just ahead or along the cold front late
THU with support from low-level convergence and diffluence
aloft. Dewpoints and moisture remain limited and no thunder or
appreciable rainfall is anticipated. Since the front arrives
later in the day, and a downsloping W wind will precede this
surface boundary, look for mild temperatures well in the 60s
Thursday, before the northern door swings open wide and brings
a talked-about chill to the area. Wind chill values will bottom
out very early Saturday in the upper teens to lower 20s.
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 3 AM Thursday...Boundary and surface temperatures progged to
recover some 10-12 degrees F on Sunday as the wedge weakens beneath
strong low level warm advection. Increased cloud cover resulting
from the upglide will temper the warmth slightly but Monday will
benefit from a much warmer start and should actually turn out warmer
than climatology. Rain chances associated with coastal trough Sunday
into Sunday night will continued to be carried but capped low as
they are likely a case of over aggressive moistening by guidance, a
seemingly common error. Rain chances should max out Monday as a cold
front moves through, though the lack of deep layer veering should
keep QPF prospects minimized as it prevents the mid levels from
moistening. After a dry and fairly seasonable Tuesday we may be
looking at another Arctic cold front on Wednesday.
.AVIATION /09Z THURSDAY THROUGH MONDAY/...
As of 06z...A weak frontal wave is approaching from the northwest.
Ahead of this system a fairly solid deck of MVFR ceilings have
developed. This moisture was very poorly initialized by model
guidance, lowering the forecast confidence regarding its tenacity.
Normally the best course is to keep lowered conditions as-is until
daybreak especially this time of year. There is some wind above the
surface layer so any VSBY restrictions likely fairly transient and
only MVFR. VFR after sunrise with just a windshift to the NNW
spreading south across the terminals this evening as the Arctic
front pushes through.
NEAR TERM /THROUGH TONIGHT/...
As of 330 AM Thursday...SCA raised for this evening through
late Friday afternoon.
Benign conditions this morning will give way to an increase in
wsw-w winds around 10 kt ahead of the approaching cold front.
Look for the CFP during late this aftn, to well offshore during
this evening. The sfc pg tightens quickly after the CFP with NW
winds increasing to 10 to 20 kt by sunset. The cold surge will
lag behind the cold front but should be in full force across the
area waters during the pre-dawn Fri hrs. Winds will further
increase to 15 to 25 kt with added gustiness to 30 kt, especially
across the warmer outer waters and closer to the Gulf Stream or
any eddies having broken off from the Stream. Significant seas
will run 1 to 2 ft this morning, building to 2 to 4 ft late this
afternoon. Further building to 3 to 5 ft, up to 6 ft 20 nm out
of the Capes late. Weak Pseudo swell from the south at 7 second
periods will dominate this morning, then give way to building
wind driven waves at 3 to 5 second periods tonight.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 300 PM Wednesday...Deteriorating marine conditions the
main headline this period as a powerful blast of cold air late
on Thursday through Friday brings gusty N winds of 20-25 KT and
choppy steep waves. Gusts to 30 KT will be common across the
outer and slightly milder offshore waters. A Small Craft
Advisory will be needed for this Arctic High in wake of a cold
frontal passage late in the day Thursday. Offshore navigation is
discouraged for small craft Thursday night and Friday, and with
the season comes the potential for hypothermia in the event of
an overboard situation. The Advisory will be likely be issued
overnight, but will allow another model run as to glean more
accurate timing of the event.
LONG TERM /SUNDAY THROUGH MONDAY/...
As OF 3 AM Thursday...Winds initially out of the SE on Sunday with a
weak coastal trough in place. Late in the day into Sunday night this
feature washes out and a SSW flow gets established and strengthens
some. A few 5 ft seas may materialize well away from shore but the
coast-parallel fetch may preclude headlines since most of the area
sees smaller waves. Monday`s forecast rather uncertain as models are
in poor agreement in timing the next front. The slower and slightly
favored solutions would allow for a moderately strong prefrontal SW
flow that would likely require an advisory.
MARINE...Small Craft Advisory from 9 PM this evening to 6 PM EST Friday