Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 160526
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
126 AM EDT Mon Oct 16 2017

.SYNOPSIS...
High pressure will migrate well offshore overnight. A strong
cold front will cross the coast Monday, accompanied by a few
showers. Drier and much cooler air will build into the area
behind the front Monday night and Tuesday, as Canadian high
pressure drops in. Dry weather and seasonable conditions will
prevail through the upcoming week, with a warming trend into
next weekend.

&&

.NEAR TERM /THROUGH TODAY/...
As of 930 PM Sunday...Clear skies across the ILM CWA at the
moment. The furthest east of the main cloud shield and pcpn
associated with the strong cold front lie along the spine of the
Appalachians across the far western Carolinas. The mid-level
ridging responsible for an outstanding weekend will get replaced
by a mid-level s/w trof beginning late in the overnight thru
Mon. Clouds and pcpn associated with a cold front is progged to
reach the western portions of the ILM CWA, ie. along the I-95
corridor, after daybreak Mon. With the sfc pg remaining somewhat
relaxed ahead of this cold front, winds will likely decouple
across much of the ILM CWA especially with skies remaining
mostly clear thru the night. With this said, have hit the fog
potential a little harder and wouldn`t be surprised to see some
locations report dense fog. The low stratus deck does not look
as prominent tonight like the previous nights when examining
model sounding data for specific points across the FA.
Widespread mid to upper 60s for lows still aok.

Previous...................................................
As of 244 PM Sunday...High pressure will give way to a fast
moving cold front and the 12 utc models are indicating it moving
off the coast around 8 PM Monday. In the mean time, winds will
remain weak overnight and with the low-level moisture expect to
see stratus and fog develop again overnight. The tricky part is
how long will it stay around. The models are indicating it will
make it to sunrise as the models are slower with the fronts
progression.

The models are depicting an anafront structure thus will slow
the  onset of precipiation a few hours than previous forecast.
Also, the nam precipiation structure is broken in a south and
north coverage to our west, but with the influx of moisture the
models increase the rain coverage as it makes it to the coast.
Mainly showers expected with an isolated possible in the late
afternoon.

Lows over night will once again be in the mid 60s temperature
overnight with highs on Monday ranging from around 70 in
Marlboro County to the upper 70s along the Georgetown coast.

&&

.SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/...
As of 244 PM Sunday...Forecast soundings show precipitable
water values plummeting to 0.25" Monday night in a strong cold
air advection regime following the daytime FROPA. It`ll be a
breezy night with lows in the mid to upper 40s and a bit of a
wind chill. The wind and cold advection both ease during the day
Tuesday and mixing to about 3000ft should allow for highs close
to 70. Thermal advection shuts off Wednesday night and there
appears to be just enough wind to prevent radiational cooling.
This should yield lows very close to those of Monday
night...perhaps a few degrees cooler inland where lightest wind
expected.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 244 PM Sunday...A broad upper trough of moderate
amplitude at the beginning of the forecast period just upstream,
will translate eastward through the period. This feature will
exit the coast late in the week, while a short-wave upper ridge
of high amplitude edges in from the west. This pattern in terms
of sensible weather should bring a mainly pleasant Fall-like mid
week period, transitioning to a warming trend late week and
next weekend. The expansive surface high itself will budge only
a bit east into next weekend, and should still have a pronounced
foothold on the region. As a result, the radiational cooling
potential could still allow seasonable, to slightly above normal
minimums into late week. Tropospheric cross-sections through
time, show arid air remains in place above 8000 feet, and thus a
dry week upcoming. Return flow should re-introduce moisture
into the area during next weekend, in the mild/warm sector, as
long range models appear to be resolving a cold frontal passage
next Monday day 8.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
As of 06Z...VFR conditions currently across the area. There is
some light fog formation as seen in regional observations, but
little in our area. Guidance has backed off significant fog
formation probably due to the affects of slightly stronger winds
advecting in from a cold front to the west. Most of the aviation
impacts will occur with this front in the form of MVFR ceilings
later today. Showers probably won`t be heavy enough for
visibility restrictions. I did put a tempo group in for
Lumberton and Florence for MVFR fog for the early morning hours
in case a lower observation or two sneaks in.

Extended Outlook...MVFR stratus possible near the coast
TUE morning in blustery post-frontal NE wind. Otherwise VFR in
the extended.

&&

.MARINE...
NEAR TERM /THROUGH MONDAY/...
As of 945 PM Sunday...Center of high pressure and associated
ridging across the local waters this evening will pull out
toward the east and further offshore late tonight. Current
winds are basically variable in direction at 5 kt or less will
become SW at 5 to 10 kt toward daybreak Mon. The sfc pg ahead of
the cold front does not tighten very much however after the CFP
the sfc pg dramatically tightens with speeds reaching SCA
threshold Mon afternoon. Significant seas will run a solid 3 ft
except 2 to 3 ft south of Cape Fear to South Santee River. An
E-ESE ground swell at 9 to 10 second periods will dominate the
significant seas with very little if any input from wind driven
waves.

Previous....................................................
As of 244 PM Sunday...Currently over the waters, light winds at
less than 5 to 10 knots are being observed. The winds are
expected to shift to the southwest tonight ahead of a cold
front. The 12 UTC models are showing the frontal boundaries wind
shifting by late afternoon Monday and are expected to increase
to 20 to 25 knots late in the day.

Significant wave height are 2 to 3 feet with a 9 sec, 2.5 to 3
ft swell from the east south-east this afternoon. Seas will
increase in height as wind increase in response the approaching
frontal boundary. Seas will increase to 3 to 5 feet by the end
of the afternoon.

SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
As of 244 PM Sunday...Rather unfriendly marine conditions in
store for the period. Near term FROPA to be followed by cold
surge/tight gradient that will keep wind and seas both solidly
in Advisory criteria. Low level jetting present Monday night
into early Tuesday at which time a few gale force gusts possible
but these winds should taper by midday Tuesday even as the
surface winds remain fairly unchanged. Wind and/or seas may
start to drop below Advisory thresholds towards the very end of
the period.


LONG TERM /WEDNESDAY THROUGH FRIDAY/...
As of 244 PM Sunday...This appears to be a period of
improvement across all marine locations, as gusty NE winds begin
to abate, allowing wave-heights to also drop. This should allow
for what could be a `Small Craft Advisory` still effective
early on Wednesday, to be dropped as the day progresses. The sea
recovery period will be a gradual one, as the high builds very
slowly to the SE. Seas of 4-7 feet early Wednesday, will subside
to 3-4 feet by early Friday, with a light to moderate NE-E chop
in the mix then. The period is dry and no TSTMS are expected at
this time over the 0-20 NM waters.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...Small Craft Advisory from 5 PM this afternoon to 6 PM EDT
     Tuesday for AMZ250-252-254-256.

&&

$$
SYNOPSIS...MJC
NEAR TERM...DCH/DRH
SHORT TERM...MBB
LONG TERM...MJC
AVIATION...SHK
MARINE...



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