Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 211821
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
221 PM EDT Sat Oct 21 2017

.SYNOPSIS...
Warm and dry weather is expected through the weekend as high
pressure moves off to the northeast. A cold front will bring
showers and a few thunderstorms late Monday and early Tuesday.
Cooler temperatures will overspread the region through mid-week
as this cold front sweeps off the coast.

&&

.NEAR TERM /THROUGH SUNDAY/...
As of 220 PM Saturday...The pattern aloft will remain highly
amplified through the near term period with a ridge across the
eastern United Sates and a trough out west. The trough will
shift across the plains during Sunday as the aforementioned
ridge drifts farther east. Although the low-level theta-e values
increase across SC during Sunday the primary axis will be found
between the Mississippi River and the Appalachians. Thus with
the main lift to the west and a dry column in place will not
include any POPs at this time for most of the forecast area. The
only exception during Sunday will be extreme southern portions
of the forecast area where there may be enough low-level
moisture return to support a few showers there. Temperatures
will be well above normal tonight and with Sunday`s highs.
Increasing high clouds could inhibit radiational cooling
overnight in some areas. Also, fog is possible overnight but is
not expected to become widespread.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
As of 220 PM Saturday...A deep mid level trough will affect the
area through the short term period. This system is just now
getting its act together out west via water vapor imagery. There
remains some timing disagreement with the operational GFS and
ECMWF so pops have been "stretched" to address this but the
overall forecast remains intact.

A mid level low will close off in the Tennessee Valley early
Monday and trudge eastward by early Tuesday. As usual with a
slow moving system like this there will be a series of fronts.
The first being a warm front that moves across overnight Sunday.
Second, a prefrontal trough associated with the main band of
convection later Monday and a lagging cold front that moves
across probably Tuesday. We continue to advertise high chance to
likely pops and I have increased the values incrementally given
the higher confidence. Low level wind fields aren`t the typical
60-70 knot deep mid latitude cyclone values at 850mb but a
lower 40-50 knots as the wind fields are more diffuse with the
slow moving cyclone. Still a high shear/low cape event is
possible regarding severe parameters. Highlights of the
temperature forecast include the possibility for some lower 80s
Monday with overnight lows in the lower to middle 60s and
possibly higher Tuesday morning before cold air advection
arrives.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 220 PM Saturday...A strong cold front will be in the
process of moving offshore sometime near the beginning of the
long term, possibly as early as daybreak Tuesday morning but
based on the spread of model guidance FROPA cold be later in the
day. In any case, best chances for severe wx appear to be
before daybreak on Tuesday with bulk of precip during this
portion of the forecast in the form of showers. Precip, along
with the front, should be well offshore by Tuesday evening.
Other than Saturday, remainder of the Long Term looks to be dry
as high pressure moves east across the eastern Carolinas.
Showers moving in advance of the next cold front may impact the
area on Saturday, but model solutions are quite divergent so
will keep pops on the low side. Temperatures will drop to normal
for late October on Tuesday in the wake of FROPA, then even
cooler for Wednesday and Thursday before a warming trend
commences for the end of the week.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
As of 16Z...Cirrus is spilling over the ridge and will become broken
later today. Mainly onshore flow will become calm this evening with
continued broken cirrus. Inland terminals may see a brief period of
MVFR fog around sunrise. Sunday, continued high clouds with a
stratocu ceiling possible at the inland terminals toward the end of
the forecast period.

Extended Outlook...Showers and thunderstorms may result in flight
restrictions Mon-Tue.

&&

.MARINE...
NEAR TERM /THROUGH SUNDAY/...
As of 220 PM Saturday...Surface high pressure will move farther
off the Jersey coast tonight through Sunday as a cold front
approaches from the west. This pattern will maintain onshore
flow across the waters with winds around 10 knots tonight and
10-15 knots during Sunday. The onshore fetch will result in seas
of 3-4 ft by Sunday.

SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
As of 220 PM Saturday...A fairly strong storm system will
affect the coastal waters through the short term period.
Overnight Sunday into Monday morning winds will shift from east
to southeast. By midday Monday winds will be from the south.
Speeds will gradually increase from 10-15 knots to a few hours
(late Monday into the evening) of 20-25 knots. Seas will
increase from 2-4 feet initially to 5-7 feet during the peak
winds thus a small craft advisory is likely.

LONG TERM /TUESDAY THROUGH THURSDAY/...
As of 220 PM Saturday...A strong cold front will be in the
process of moving across the waters near the beginning of the
period and should be well east of the forecast area by Tuesday
night. Tuesday may start off with an advisory or exercise
caution headlines in effect for all waters for seas of up to 6
ft, but do expect seas to decay early on as winds turn offshore
with FROPA. Expect steadily improving conditions through mid-
week.

&&

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

&&

$$

SYNOPSIS...REK
NEAR TERM...SRP
SHORT TERM...SHK
LONG TERM...REK
AVIATION...SRP
MARINE...REK/SHK/SRP



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