Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 142216
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
616 PM EDT Thu Sep 14 2017

.SYNOPSIS...
Fair and mainly dry weather is expected through the weekend as
high pressure builds from the north. Tropical Storm or Hurricane
Jose is expected to move between the Carolinas and Bermuda
Sunday and Monday. Strong rip currents and dangerous surf
conditions will develop beginning this weekend and should
persist into early next week.

&&

.NEAR TERM /THROUGH FRIDAY/...
As of 630 PM Thursday...Showers a hanging on in a band located
between Lumberton and Elizabethtown, with a few more isolated
showers just west of Burgaw and Garden City Beach. With the
exception of the heaviest activity just west of Elizabethtown,
showers should dissipate within the 30-45 minutes. The showers
approaching Elizabethtown could persist through 730-800 PM
before the stabilizing boundary layer robs them of needed
updraft energy and they dissipate as well.

No changes were made to overnight low temperature forecasts.
Winds becoming calm should favor good radiational cooling,
particularly given that the airmass is warm and rather humid.
Model analysis of vertical change in dewpoints with height
shows we may hang on to just enough boundary layer moisture for
patchy fog development late tonight. This has been added to the
forecast with this early evening update. A look at the 00Z
soundings from CHS and MHX will reveal how substantial this fog
potential might be. No other significant changes. Discussion
from 300 PM follows...

Low-level water vapor channel shows a stream of exceptionally
dry air aloft upstream of the region set to invade NE SC and SE
NC and shut down convection in concert with diurnal cooling into
late afternoon and early evening. As much of the diurnal
cumulus dissolves into the night, mostly clear skies will
prevail. Mid-level clouds will sweep swiftly SW to NE over
inland areas along the leading edge of an upper trough
translating eastward across the Mid-Atlc states tonight. Aside
from these intermittent mid-level clouds, clear skies are
expected. At the surface a very flat pressure pattern is on tap
tonight and Friday, resulting in light SW winds overnight,
becoming light W-WNW in the morning, then light and variable
Friday. The sea breeze albeit weak Friday, will bring SE winds
in the afternoon near the coast and along the coastal interior
through afternoon. Westerly flow in the lower troposphere Friday
coupled with dry air above 700mb will make it difficult for
convection processes. With good surface heating however,
moderate cumulus can to be expected, as H8 RH bumps upward
through afternoon. MaxT Friday 85-88 inland 81-82 beach.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 300 PM Thursday...Moisture from the south will be cut off
heading into the weekend as ridge aloft builds up from the
south and winds begin to veer around to the W-NW. Initially winds
will remain very light and driven mainly by sea and land breeze
late Fri into early Saturday. But, the gradient should tighten
as Jose begins to move north Sat aftn into early Sun. This
should produce an increase in winds and will also help shift
winds around to the north. Plenty of dry air remains upstream
and therefore expect fair weather through the period but as we
move into the latter half of the weekend, we may see more in the
way of some cirrus streaming in and possible some increased
clouds and some showers running around the outer limits of the
circulation of Jose, remaining mainly off shore but heading
closer to coastal NC heading into Sunday.

Pcp water values near 1.3 inches will decrease in the northerly
flow and increased subsidence aloft through Sat, but may see
enough convergence to squeeze out a stray shwr along the sea
breeze boundary Sat aftn. Otherwise, expect plenty of sunshine
and warm temps in the mid 80s during the aftn and mid 60s to
near 70 for overnight lows Fri night and Sat night.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 300 PM Thursday...Tropical Storm Jose, forecast to be
back at hurricane strength by Sun, will pass well east of the
coast early in the period. Mid-level trough will pick up Jose
and lift the storm north-northeast Sun through Tue, passing
about 350 miles east of Cape Fear on Mon. There still remains
uncertainty with respect to Jose`s timing and track but it
continues to look like the only impact Jose will have on the
area will be dangerous surf conditions for the end of this week
and the start of next week.

Outside of Jose, the period will be dominated by surface high
pressure over much of the east coast and weak mid-level ridging. The
only real chance for rainfall during the period appears to be late
Sun or Sun night, but even this is uncertain and will depend on how
much deep moisture is spread over the eastern Carolinas by Jose and
how strong the convergence zone is and where it sets up. There may
be some isolated weak convection late in the period associated with
the Piedmont trough but do not have a lot of confidence in this
right now. Temperatures will run a few degrees above climo through
the period.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
As of 00Z...Showers in the LBT vicinity should dissipate around
00Z with VFR conditions anticipated through 06-08Z. Then the
potential of MVFR or IFR condition develops late tonight due to
ground fog formation. Low-level moisture is marginal, but I
imagine there will be patches of ground fog, particularly in the
LBT vicinity where earlier rainfall should seed the lowest
portion of the atmosphere with additional moisture. VFR
conditions should redevelop after daybreak and continue through
Friday.

Extended Outlook...Mainly VFR conditions thruout the forecast
period. The exception will be each morning where MVFR/IFR
conditions are possible from reduced vsby in BR/FG.

&&

.MARINE...
NEAR TERM /THROUGH FRIDAY/...
As of 630 PM Thursday...Seabreeze-enhanced winds were a solid 15
knots over the past few hours, but should diminish and veer more
westerly overnight as previously forecast. Buoys observations
support 2-3 foot seas through the night, highest near and north
of Cape Fear where Tropical Storm (perhaps Hurricane again?)
Jose`s swell will have the largest impact. Changes to the
forecast with this early evening update were generally minor.
Discussion from 300 PM follows...

This is a favorable marine period tonight and Friday because
the pressure pattern will remain quite flat. Light SW winds
tonight will become W-WNW very early Friday. As afternoon
heating inland gears up, a sea breeze will bring SE winds to the
waters but mostly 10 KT or less Friday afternoon. SWell from
Jose will become more significant beyond tomorrow day, and for
tonight and Friday seas 2-3 feet every 9-10 seconds becoming
10-11 seconds Friday. Longer period E swell is fanning onshore
every 13 seconds, but it remains weak in amplitude. A few
showers are possible north of Cape Fear this evening. As a
result of these elements, a nicely rolling, almost `glassy at
times` SE swell to welcome mariners, free of wind and lightning
hazards.

SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 300 PM Thursday...Very weak gradient flow will keep
winds light and dominated by sea and land breeze late Fri
through early Sat, but as Jose lifts north the gradient will
tighten and winds should become a little stiffer out of the
north Sat aftn through Sat night. The strength of these
northerly winds will be dependent on the strength of Jose as it
moves north in the off shore Atlantic waters. For now, will
indicate winds up around 15 kts after midnight Sat night into
Sunday. May also see some clouds and showers around the outer
limits of Jose affect the waters heading into Sunday.

With such light gradient winds, expect seas to be dominated by
longer period swell from Jose reaching up to 12 to 14 seconds
out of the SE overnight Fri into Sat. By Sat aftn, Jose will be
on the move north and should aid in tightening the gradient
winds out of the north. The exact strength of winds and height
of the seas will be dependent on the exact track and strength of
Jose as it moves up through the off shore waters to our east.
Overall should see seas 2 to 4 ft through Fri night but the
combination of increasing winds and swell from Jose should
produce a decent rise in seas through Sat into Sun possibly
upwards of 7 to 9 ft Sat night into Sun.

LONG TERM /SUNDAY THROUGH MONDAY/...
As of 300 PM Thursday...North to northeast flow will continue through
the period with elongated surface ridge axis to the west and
Tropical Storm Jose to the east. The future for Jose remains unclear
and this keeps confidence in the coastal waters forecast low. Jose
will move north and eventually northeast during the period but the
storm`s proximity to the coast as well as its strength remains
uncertain. For now have northeast winds peaking around 15 kt very
late Sun night into Mon morning, but this is with Jose passing about
350 miles east of the coast. A closer pass would result in higher
wind speeds. Seas during the period will be mostly made up of swell
from Jose, although the strength and proximity of the storm to the
coast will determine how high seas are. While there is potential for
double digit seas for now the forecast is 5 to 8 ft Sun
gradually subsiding to 3 to 4 ft on Tue.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...Coastal Flood Advisory until 7 PM EDT this evening for NCZ107.
MARINE...None.

&&

$$

SYNOPSIS...RGZ
NEAR TERM...MJC/TRA
SHORT TERM...RGZ
LONG TERM...III
AVIATION...TRA



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