Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 160056

Area Forecast Discussion
National Weather Service Wilmington NC
756 PM EST Fri Dec 15 2017

A cold front will shift off the coast this evening and high
pressure will build in over the Carolinas for the weekend. With
a southerly wind temperatures will rebound and move above
average by Monday and Tuesday. Another cold front pushes across
the region late Tuesday to drop temperatures back down again as
high pressure returns through mid to late week.


As of 8 PM Friday...Cold front still wavering over the forecast
area but latest guidance still has this feature getting kicked
offshore overnight. Latest IR satellite loops show back edge of
mainly mid-deck cloud cover associated with the font gradually
dropping SE so total clearing by daybreak not out of the
question. In any case, no precip is expected and forecast
remains on track with another chilly night in store. Previous
discussion from this afternoon follows:

Frontal wave moving up into the Outer Banks. This has dragged
the trailing front back to the north of the region and allowed
the mid level cloud deck to fill in. Forecast soundings continue
to show dry air outside of this layer so still not expecting
any rain. The front will push back through to the south this
evening leading to a fairly deep layer veer to NW flow. This
should lead to a rapid clearing trend from NW to SE. Lows
tonight will bottom out in the low 30s NW to upper 30s far
southern zones. Highs tomorrow will have trouble exceeding 55 in
the new, cooler airmass behind the front.


As of 3 PM Friday...A short-wave, in a deamplifying phase, will
eject across the Red River Valley of Texas Saturday night,
gradually becoming absorbed in WSW flow on approach to the
Appalachian Virginias Sunday night. At the surface, high
pressure centered over the Carolinas Saturday night, will slip
offshore by Sunday evening. These features will team, to produce
a sensible weather trend of warm air advection Sunday,
potentially resulting in 16-19 degree F minimum temperature
differences Sunday daybreak versus daybreak Monday, along with a
slight chance of a light rain shower very late Sunday into
early Monday. Moisture associated with the weakening short-wave,
will nearly saturate the 925-700 l and bringing the upper-
level energy across the region.ayer late Sunday night and a few
sprinkles or light rain showers generated by weak support aloft
cannot be ruled out entirely into early Monday.


As of 300 PM Friday...On Monday the 12 UTC runs of the ECMWF
and GFS are showing a trough/cutoff low south of the 4 corners
area of the great southwest. The models begin to diverge and by
Tuesday the GFS is faster pulling the cutoff low to the east. By
Wednesday morning the GFS has dissipated this wave and it has
this feature accelerating to the east coast in the zonal flow.
The ECMWF still has a cutoff over the Oklahoma and Arkansas
border and the model weakens and dissipates this features as if
has moves off the east coast. Therefore confidence in the
extended forecast is not high.

The GFS models continue to show a warming trend through Tuesday
before moving a cold front through the area between Tuesday and
Wednesday and bringing down a shot of cooler temperatures, but
the ECMWF keeps the shot of colder air farther north. So the
forecast will side with the model blend and this will bring in
cooler temperatures for Wednesday.

Rainfall chances looks to be the best on Monday into Tuesday
with the favoring of the GFS solution stronger southern energy
out of the southwest and pulling the cutoff low out quicker.
With the the west-southwest flow remaining over the region
expect to see small chances of rain Wednesday through Thursday.


As of 23Z...High confidence of VFR through the TAF period. Mid
to high levels clouds will continue to stream across the area
along a frontal boundary that has been draped across the region
the past 23 hours or so. Surface winds will become light north
around 3 kt with mid clouds decreasing. After sunrise winds will
be light NW-NE becoming SW by the end of the TAF valid period
with clods dissipating and giving way to clear skies as the
front finally sags to the SE.

Extended Outlook...VFR. VFR tempo MVFR/SHRA Monday through Tuesday


As of 8 PM Friday...Cold front still has yet to move offshore so
winds remain at 10 to 15 kts from the SW. Still expect the
front will get kicked east of the waters overnight, with winds
turning NW and finally N by daybreak. Seas still in the 2 to 4
ft range. Do not expect any headlines during this period.
Previous discussion from this afternoon follows:

W to SW prefrontal flow regime has relaxed near shore as the
front has retrograded. This boundary will push back through this
evening turning winds to the NW and adding some gustiness but
expect wind and seas to remain below any advisory or headline
thresholds. Such winds will last into Saturday morning but the
remainder of Saturday will see high pressure build in and much
lighter if not variable wind flow.

As of 3 PM Friday...A welcoming and pleasant marine environment
for this period, with high pressure nearly overhead of the
waters Saturday night, slipping offshore of the 0-20 NM zones by
Sunday evening. As a result, winds will become light and
variable Saturday night, then S-SW Sunday, 12 kt or less. Sunday
night as the high offshore slips farther SE, winds will trend
to W early Monday up to 15 KT, as the pressure gradient tightens
a bit. Still, with offshore flow, seas will not be problematic.
Light to glass conditions Saturday night will see perhaps a
lazy 10 second E swell around a foot. Into Sunday night, SW-W
wind chop will pick up a little bit. Dry this period, except
perhaps a sprinkle late Sunday and early Monday, but no
visibility restrictions are expected.

As of 3 PM Friday..An unsettled period for the marine forecast
with west to southwest flow on Monday into Tuesday with a cold
front pushing across the waters later Tuesday into Wednesday.
Will have to watch if small craft conditions develop after the
cold frontal passage but otherwise expect seas of 2 to 4 feet.





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