Area Forecast Discussion
Issued by NWS Wilmington, NC-- Remove Highlighting --
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FXUS62 KILM 070939
Area Forecast Discussion
National Weather Service Wilmington NC
439 AM EST Wed Dec 7 2016
A weak high will yield fairly seasonable weather today and
tomorrow before a powerful cold front arrives late Thursday. A
very cold weekend is then in store for the area with a gradual
warmup starting Sunday. A weak cold front will move through
.NEAR TERM /THROUGH TONIGHT/...
As of 330 AM Wednesday...Weak, and dry, high pressure will
build into the area today and persist thru tonight. The sfc pg
will relax this morning and especially by this aftn thru tonight
as the low off the VA Capes progresses ene further away from
the FA. Looking at NNW to NNE winds diminishing to less than 5
mph this aftn and likely becoming nearly calm after sunset thru
tonight. an overcast low stratus clouds this morning should
scour out later this morning by midday due to drier air aloft
mixing down to the sfc. This will leave thin to opaque upper
level cirrus traversing the area this aftn and tonight.
Temperatures this period will run at to slightly higher than
the 30 year normals. Overall, not bad of a day compared to the
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
-- Changed Discussion --As of 345 AM Wednesday...Longwave upper pattern this period
exhibits a rather small amplitude trof affecting the entire
conterminous U.S. with the strong westerlies having been pushed
southward to Mexico and the southern Gulf of Mexico. This
pattern in itself would result in temps this period running at
or slightly below the 30 year normals. However, for Thu, sfc
cfp to occur in the late aftn. Very limited moisture
accompanying this front itself along with no tapping of any
source expected. As a result, have only indicated low chance
POPs ie. Isolated or widely scattered at best. And even this may
be too high.
Models indicate the flow aloft ends up with enough amplitude to
tap some of the Arctic air in Canada and bring it southward into
the U.S. this period. After the 1st CFP late Thu, a secondary
CFP occurs Thu night. Modified Arctic air will follow the 2nd
CFP and advect across the FA during late Thu night thru Friday
night. This round of Arctic air is associated with a 1035-1040
mb High that broke off from the main Arctic High of 1055+ mb,
over west central Canada. The broken off High will ridge into
the FA from the south central U.S. during Friday, with it`s
center just NW of the ILM CWA by daybreak Sat. Dry and cold
conditions expected. Wind chill readings Fri night will drop
into the upper teens inland to near 20 at the coast.
Other than a brief warm-up ahead of the CFPs on Thu, temps
there-after will average 10 to 15 degrees below the climo norms
Fri into Sat. This definitely is the 1st bonafide cold air
outbreak to commence the Meteorological Winter which started
-- End Changed Discussion --
.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 3 AM Wednesday...A very cold airmass remains in control on
Saturday though as the center of the high builds overhead winds will
diminish. Warm advection will begin atop this airmass Saturday night
but surface temperatures will still fall below 30 for all but SC
beaches. It is then on Sunday when we will appreciate the warming at
the surface as high pressure moves off the coast and the chill
abates. Moisture will be on the rise in the low levels but zonal
flow in the mid levels should preclude much moistening above. This
would imply that the next cold front will be hard-pressed to produce
any rainfall but some very low POPs seem warranted Sunday night into
Monday. This zonal flow will also mean little meaningful cold air
with the front. Late period temperatures look seasonable if not a
few degrees above.
.AVIATION /09Z WEDNESDAY THROUGH SUNDAY/...
As of 06Z...Guidance has backed off considerably on showing lowered
flight categories overnight due to visibility. Since the wind will
remain elevated enough for weak mixing this seems plausible. There
is little to rout out this low level moisture in the form of IFR
ceilings however. This will have to wait until deeper mixing ensues
after sunup. VFR from thereafter.
Extended Outlook...Fog possible Wednesday night. VFR conditions
expected to prevail late week through this weekend.
-- Changed Discussion --NEAR TERM /THROUGH TONIGHT/...
As of 330 AM Wednesday...SCA and SCEC conditions early this
morning, with conditions improving quickly during this period.
Improving marine conditions expected today. The gusty NNW to
NNE winds early this morning will diminish from south to north
as the modest low off the VA Capes pushes ENE further away from
the local waters. This will result in the sfc pg relaxing and
winds diminishing to around 10 kt this aftn and possibly less
than 10 kt tonight. Not much of a pressure pattern tonight which
will result in a variable wind direction, however will indicate
a dominate direction in lieu of going VRBL. Significant seas
will also be subsiding this period. With short period wind
driven waves dominating the seas spectrum, expect the seas to
subside quicker. Seas will diminish to 3 ft or less by this
evening, and to 1 to 2 ft during tonight.
SHORT TERM /Thursday THROUGH FRIDAY NIGHT/...
As of 345 AM Wednesday...Subtle marine conditions Thursday will
give way to 2 CFPs, the 1st late Thu aftn and the more potent
one during Thu night. Potent, meaning modified Arctic air will
advect across the area later Thu night thru Friday night. A
tightened sfc pg and cold surge will combine to produce gusty NW
to NNW winds at SCA thresholds. Models may be underdone with the
winds across the area waters due to mild SSTs near the coast.
Will have plenty of mixing across the area waters and especially
across the warmer waters of the Gulf Stream and any warm
eddies that may have broken off. The center of the modifying
Arctic High will lie just NW of the area waters by daybreak Sat.
This will result in winds diminishing-some later Fri night.
Significant seas will be at their lull of this period during
Thu...with a 6 to 7 second period SE pseudo swell temporarily
dominating. Wind driven waves at 3 to 5 second periods will
become the dominant player in the significant seas spectrum
after the CFPs, Thu night and continue thru Friday night. With
a slightly hier offshore windspeed forecast than what the models
indicate, the seas will end up slightly hier, by 1 to 2 feet,
than what Wavewatch3 indicates. NWPS runs, ie. Swan Model, has
taken into account our local wind fcst when this model was
executed. With an offshore wind trajectory, a relatively large
range of seas will occur, with 1 to 3 ft near shore and 3 to 6
ft across the outer waters.
LONG TERM /SATURDAY THROUGH SUNDAY/...
As OF 3 AM Wednesday...Chilly high building in from the north
Saturday to bring an abating N wind that will veer slightly.
Additional veer to E early Sunday as a weak boundary develops
along the coast. Later Sunday the wedge will break down,
bringing a rapid turn to the S or SW. Wind speeds will be on the
rise as a cold front approaches from the NW but advisory not
expected at this time, but cautionary headlines are possible.
-- End Changed Discussion --
MARINE...Small Craft Advisory until noon EST today for AMZ250-252-254.