Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 222219
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
619 PM EDT Sat Sep 22 2018

.SYNOPSIS...
High pressure will prevail through early next week. An upper
trough approaching from the west, will gradually push a cold
front this way, reaching our coast Friday. Drier and slightly
cooler high pressure is expected build in next weekend.

&&

.NEAR TERM /THROUGH SUNDAY/...
As of 615 PM Saturday...Daytime cumulus are fading away and
mostly clear skies are anticipated this evening. Light winds
should provide good radiational cooling much like we saw last
night, and lows will again fall into the 65-70 range. We`ve been
in an unusually warm airmass all month it seems, so it`s odd to
think even these numbers are 3-6 degrees above normal for the
date. Changes for the overnight forecast were all minor except
for bumping up lows on the beaches by a few degrees.

Discussion from 300 PM follows...

The flat nature of the cumulus this afternoon are indicative of
the convection-suppressing mid level ridge overhead. Even
without this feature the area would likely stay rain- free with
such low available moisture especially aloft. Forecast soundings
show a fog signal once again tonight though not as strong as
last night so will relegate to patchy and leave out dense.The
main impact will likely only be to aviation save for perhaps in
the LBT vicinity. The mid level ridge moves off the coast on
Sunday but will still keep enough dry air in the mid levels to
preclude meaningful rain chances. A moistening of the low levels
in easterly flow makes non- measurable tropical showers
seemingly more likely than measurable rainfall. Similarly with
the capping inversion precluding deep convection will leave out
thunder. A cold front drops into just north of the area by
evening, too moisture starved to represent much more than a wind
shift.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
As of 320 PM Saturday...High pressure pushes in from the NE on
Sunday night behind moisture-starved frontal boundary. Models
are spitting out some light rainfall across parts of the area
but with a continued light SW flow borne of the western
periphery of the offshore mid level ridge this may be asking a
lot of the continued dry air in forecast soundings. Despite the
continued NE flow temperatures and dewpoints don`t really change
heading into Monday night.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 320 PM Saturday...Bermuda to Bahama upper ridge will be
holding on Tuesday and Wednesday before shifting east, as an
upstream and broad upper trough, and associated its axis, edge
eastward across the Mississippi Valley. It appears the trough is
of sufficient latitudinal amplification to bring a moderate
degree of 925-700mb Gulf moisture pluming NE ahead of a slowly
approaching cold front. As such, rain chances ramp up a bit
Thursday and Friday. The cold front to cross the coast Friday
night. The front may be slowly clearing the SC coast into
Saturday, and overall, drier and slightly cooler air should
filter in Saturday.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
As of 00Z...High pressure will stay in control through the
forecast period. A stationary frontal boundary will remain north
and west of the region. Dry air just above the stable boundary
layer overnight should help with dispersion of moisture which
will make fog development difficult. Will likely have some minor
restrictions to show the possibility where more surface
moisture is present. VFR again on Sunday with clear skies and
some afternoon Cu possible.

Extended Outlook...Mostly VFR through this period. However,
flight restrictions are possible in late night/early morning
fog/stratus each day. And brief flight restrictions are
possible within showers/thunderstorms Sunday through Tuesday,
especially during the afternoon/evening hours.

&&

.MARINE...
NEAR TERM /THROUGH SUNDAY/...
As of 615 PM Saturday...Light southeasterly winds will turn
more northerly nearshore late tonight with a landbreeze. With
such light wind speeds there should be no impact to mariners.
Seas are only 1-2 feet almost exclusively in 11 second easterly
swell. Changes with this forecast update were all minor.
Discussion from 300 PM follows...

Conditions remain minimal with such a light gradient in place
only a minor SE swell. As pressures rise over the NE U.S. the SE
winds locally could turn more easterly on Sunday. Little change
in seas expected.

SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
As of 320 PM Saturday...Cold front sags through from the south
SUnday night turning winds to NE and increasing speed by about
a category in addition to adding a little gustiness. Seas should
open up to 3-4 on Monday and possibly a few 5 footers Monday
night offshore, but only across NC waters.

LONG TERM /TUESDAY THROUGH THURSDAY/...
As of 320 PM Saturday...Weak tropical low pressure, or possibly
just a surface trough will approach the Carolina coasts late
Tuesday night, dissipating as it lifts to the north across the
NC Outer Banks Wednesday. Well established SW wind flow will
follow in wake of this feature Thursday. As the low nears
Tuesday, we may see gusty NE winds and elevated seas, so an SCA
or SCEC possible at this time Tuesday. TUesday onward, isolated
TSTMs can be expected to impact the 0-20nm waters.

&&

.TIDES/COASTAL FLOODING...
As of 320 PM Saturday...Still anticipate warning level (6.7+ft
MLLW) during high tides for the next few days, likely through
the full moon on 24th/25th as the astronomical tides add to the
flood wave coming down the river. The current ETSS has
consistently been overdone and it`s forecast of 8.2 ft shall be
no exception. Have tempered these values with guidance from our
Service Hydrologist and currently forecasting 7.3 ft this
evening. Values slightly exceeding 8 ft certainly possible as
the moon waxes to the full Harvest Moon.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...Coastal Flood Warning until midnight EDT tonight for NCZ107.
MARINE...None.

&&

$$

SYNOPSIS...MJC
NEAR TERM...TRA/MBB
SHORT TERM...MBB
LONG TERM...MJC
AVIATION...21
TIDES/COASTAL FLOODING...MBB


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