Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 182332
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
632 PM EST Sat Nov 18 2017

.SYNOPSIS...
A strong cold front will pass through the area late tonight and
Sunday morning. The front may be accompanied by some gusty late
night showers. The front will usher in much colder and drier air
with Monday seeing the lowest daytime highs with the possibility
for a freeze or frost late Sunday night and Monday night.
Temperatures will moderate Tuesday and Wednesday. Forecast
uncertainty increases mid to late next week as another cold
front moves into the area. The weather could turn unsettled and
will hinge on the track of developing low pressure in the
Gulf of Mexico.

&&

.NEAR TERM /THROUGH SUNDAY/...
As of 300 PM Saturday...A potent shortwave as seen on water vapor
imagery across Kansas will rapidly move across the area tonight all
the while shearing out. This will bring a moisture challenged cold
front across the area with timing a couple of hours either side of
12 UTC. Models have trended drier with the front with at most a
broken line of fast moving showers moving from west to east. Winds
will crank up tonight ahead of the front at 15-25 MPH with higher
gusts. With the fast moving flow, clouds and what few showers there
are will clear out quickly Sunday. Lows tonight will not fall off
much with the gradient increasing with middle to upper 50s common.
For Sunday there is some cold air advection but certainly not
overwhelming with highs in the lower to middle 60s.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
As of 300 PM Saturday...With PW values a mere 0.2" for much of the
period there will likely not be a cloud in sight. The exception may
be some wisps of cirrus Monday night as some upper jetting
strengthens off the coast and the Carolinas end up near the left
entrance region. Mid level clouds may also be lurking close by to
our SW in a tongue of enhanced warm advection. While moisture will
be in short supply cold air will not. Forecast soundings show as
little as 2000ft of vertical mixing through Monday afternoon,
keeping high temperatures mired in the 50s even as moderate warm
advection will be occurring at higher levels. Both nights will
feature an inland light freeze while temperatures closer to the
water remain in the upper 30s.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 300 PM Saturday...A couple of short wave troughs in the
southern stream will have some impact on area weather in much of the
extended period though confidence is currently low in exactly what
those impacts will be due to model divergence.

The first upper trough will bring a chance of showers to the area
Tuesday into Wednesday as a cold front moves through the area. After
this fropa, the second upper trough could spawn low development
along the front off shore and bring rain to the area Thursday into
Friday.

For now...the forecast reflects slight chance to chance pops Tuesday
into Wednesday with slight chance pops for Wed night into Friday.
Temperatures will be near seasonal normals of the mid 60s Tuesday
and Wednesday before falling back into the mid to upper 50s for
Thursday and Friday.  Slightly warmer temperatures are expected
Saturday with highs in the upper 50s to lower 60s.  Mins will see a
similar trend falling from the mid to upper 40s Tuesday night to the
mid 30s to around 40 Thursday night before rebounding to the 40s by
Saturday night.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
As of 23Z...Southerly low-level jetting will spread across the
eastern Carolinas overnight ahead of a cold front. Gusts will
diminish from west to east on Sunday as high pressure builds in
from the west. Expect primarily VFR ceilings, with a narrow band
of scattered light showers possible, mainly along the front.

The worst of the wind will remain just above the surface
tonight due to poor vertical mixing. Winds 500-2000 feet AGL
should increase to 35-40 knots from the south between 03-05Z
Sunday. With the front expected to be offshore by sunrise
Sunday, post-frontal winds should veer northwesterly with speeds
gradually diminishing throughout the day.

Extended Outlook...VFR conditions are expected Sunday through
Tuesday morning. There is potential for MVFR ceilings Tuesday
night through Wednesday.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 300 PM Saturday...Quiet enough over the coastal waters
currently with with winds in the lower teens and seas three feet or
so. Winds and seas will rapidly increase this evening through the
overnight hours well into a 25-30 knot range. This, as strong low
level jetting precedes a cold front. There may be some gusts into
Gale criteria but since the strongest winds will be in warm air
advection, the need for a Gale warning isn`t a given. Winds turn
offshore early Sunday, from the north, northwest at 15-20.
Significant seas ramp up quickly from the current three feet to well
over small craft criteria by midnight and continue through most of
the day Sunday.

SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
As of 300 PM Saturday...Sunday night brings a moderately strong yet
relaxing gradient as chilly high pressure airmass builds in from the
west. Flow will veer slightly from NW to N or even NE and advisory-
worthy wind speeds should be outside of the 20nm zones. On Monday
expect a more pronounced relaxation of winds and seas due to the
high moving overhead. The high remains over the area Monday night
while elongating to the east. Winds will remain minimal and turn
onshore while seas smooth into the 1-2 ft range most areas.

LONG TERM /TUESDAY THROUGH THURSDAY/...
As of 300 PM Saturday...Return flow behind the departing high
Tuesday will buckle as a coastal trough develops along the Southeast
coast. Winds should turn easterly on Tuesday, then perhaps
southeasterly for a time Tuesday night as the trough makes its
closest approach to shore, but by Wednesday morning the feature
should retreat back offshore as high pressure advances across the
Ohio Valley and shifts our winds to a more north to northeast
direction. Light winds and slight seas are expected until Wednesday
night or Thursday when NE winds of 15 to 20 KT could build seas to 4
to 5 FT with 6 footers possible at 20 NM.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...Small Craft Advisory until 6 PM EST Sunday for AMZ250-252-254-
     256.

&&

$$
NEAR TERM...JDW/SHK
SHORT TERM...RJD
LONG TERM...TRA
AVIATION...CRM/TRA


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