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-- Discussion containing changed information from previous version are highlighted. --
989
FXUS62 KILM 231440
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
Issued by National Weather Service CHARLESTON SC
1040 AM EDT Wed Aug 23 2017

.SYNOPSIS...
An approaching cold front will bring increasing storms over the area
late today into Thursday. Canadian high pressure will bring an early
fall feel Friday and into the weekend. Breezy conditions may develop
late Sunday into Monday, as a possible tropical low passes offshore
and interacts with the Canadian high.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
A weak upper vort moved off the coast around daybreak, taking
along with it scattered showers and tstms. 500 mb analysis
indicates fairly widespread negative vorticity advection today
in the wake of the shortwave. The resulting subsidence should
result in mostly dry weather through mid afternoon, aside from
an isolated sea breeze shower or tstm. Late this afternoon a
strong shortwave approaches from the northwest and a cold front
moves toward the area. Latest high-res model data brings the
leading edge of the showers and tstms into the western zones
late this afternoon or early evening. Shear will be increasing
to around 20 kt by late today which is not terribly impressive
but could assist with some quasi-linear organization of
convection along the front. CAPE values will be at a relative
maximum late this afternoon around 2,000 J/kg. Severe
thunderstorm potential will depend on the exact timing of the
frontal convection, though it still appears that isolated severe
thunderstorms will be possible between about 5 PM and 11 PM.

The front will stall across the area tonight even as convection
pushes offshore by Thursday morning. Cool advection lags, so
mins will remain elevated tonight, mid 70s at the coast to low
70s far NW zones.
-- End Changed Discussion --

&&

.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
As of 300 AM Wednesday...A cold front will move through the area
Thursday and off the coast Thursday night accompanied by scattered
showers and storms.  The greatest chances for rain during this
period will be over the south and east.  Small pops will longer
along the coast Friday and south coast Friday night in NE flow as
low level moisture is slow to be driven out of the area.  Max
temperatures will be in the mid to upper 80s both days with mins in
the upper 60s to lower 70s with mid 70s at the beaches.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
As of 300 AM Wednesday...At the surface a cold will push into the
Bahamas by early Saturday with high pressure building down into the
Carolinas. Saturday should be cooler and mostly dry although the
easterly flow may keeps some low clouds and perhaps a light shower
or two offshore around.

The forecast gets interesting later in the period when the global
guidance spins up what could be a tropical system along the residual
front and moves it up off the southeast coast. The guidance has been
showing this for a few cycles but the disclaimer of its pretty far
out in time still holds. I did keep a partly to mostly cloudy
forecast intact with some pops increasing especially along the
coast. Temperatures will be on the cool side especially for highs
more near normal for overnight lows.

&&

.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
As of 11Z...Isolated showers and thunderstorms are possible
coastal areas this am and along the sea breeze this aftn.  More
numerous showers and thunderstorms are expected to develop ahead
of a cold front and affect all the terminals.  Have continued
VCTS with -SHRA at all terminals late this afternoon into tonight.
Generally expect MVFR with SHRA but brief IFR is possible.

Extended Outlook...Showers and t-storms Thursday associated
with a cold front could produce localized IFR conditions.
Most showers and storms will push offshore Thursday night
into Friday. MVFR ceilings could linger, especially near
the coast Friday.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 300 AM Wednesday...High pressure offshore and a cold front
approaching from the NW will pinch the gradient today causing SW
winds to increase across the waters. SW winds of 10-15 kts will
slowly increase to 15-20 kts this evening and tonight, while subtly
veering more to the W/SW. This increase in wind speed will allow the
wind wave contribution to the wave spectrum to increase, with a 3-4
ft/4 sec SW wave topping a persistent 2-3ft/9sec SE swell. These two
groups combined will produce significant seas building from 2-3 ft
early, to 3-4 ft late, and at this time no cautionary statements are
expected. Showers and tstms are expected across the waters late
tonight as well, moving from west to east mostly after midnight,
with gusty winds, lightning, and heavy rainfall.

SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
As of 300 AM Wednesday...Westerly flow of 10 to 15 KT Thursday will
shift to the NE Thursday night and increase 15 to 20 kt by Friday
night.  Seas will build from 2 to 3 FT Thursday to 3 to 5 feet
Friday night.

LONG TERM /SATURDAY THROUGH SUNDAY/...
As of 300 AM Wednesday...Not the best of weekend`s coming up for the
marine community as high pressure will be building down into the
area from the north. At the same time a front will become stationary
to the south and keep the gradient elevated. For basically the
entire period expect northeast winds of 15-20 knots. Seas will be
elevated as well with values from 3-6 feet.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.

&&

$$
SYNOPSIS...
NEAR TERM...JRL
SHORT TERM...JMC
LONG TERM...JMC
AVIATION...
MARINE...