Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 190204

Area Forecast Discussion
National Weather Service Wilmington NC
1003 PM EDT Tue Oct 18 2016

Warm and dry weather over the next several days will give way to
a strong cold frontal passage Friday. This will knock temperatures
down into the 40s for lows this weekend, with highs in the 60s. A
gradual warming trend early next week will bring temperatures to
about normal for the season, accompanied by fair conditions.


As of 10 PM...Going forecast has a fine handle on things with high
pressure in control. Previous discussion from 3 PM follows.

Surface high pressure is centered offshore but extends a ridge axis
westward across the Carolinas. In the upper levels high pressure
sits across the Southeast states as well. This means except for a
shallow layer of Atlantic moisture near the surface, the atmospheric
column will remain very dry.

Areas of fog may again develop late tonight as radiational cooling
brings boundary layer temperatures down below the dewpoint. Forecast
soundings suggest good moisture (60 degree dewpoints) will extend
about 1000 feet vertically near the coast and 500 feet vertically
inland. This is certainly sufficient for fog. The only potential
problem with a foggy forecast is winds just off the surface should
increase overnight to around 15 knots. While not enough to preclude
fog, this may keep fog coverage more in the or "areas" category
instead of "widespread." Forecast lows are near 60 with lower 60s
near the beaches.


As of 3 PM Tuesday...The surface ridge of high pressure will grow
weaker on Thursday as a trough approaches from the northwest and as
low pressure develops northeast of the Bahamas. The National
Hurricane Center suggests there is an 80 percent chance a tropical
or subtropical cyclone will form out of the storminess currently
east of the Bahamas. Model ensembles show this potential development
will not get close enough to the Carolina coast for any direct

The trough approaching from the northwest does not extend across
enough latitude to tap moisture from the Gulf of Mexico, and with
such a late breakdown of the ridge off the Carolina coast there will
be very little inflow from the Atlantic either. This means the
system will remain very moisture-starved, and I am not introducing
any showers into the forecast through Thursday night. Mainly clear
skies and above-normal temperatures should continue.


As of 3 PM Tuesday...Chief headline this period remains a strong
cold frontal passage Friday ushering the chillest air of the fall
season this weekend, with lows in the 40s and maximums not likely
to crest 70 degrees Saturday and Sunday. Along and just ahead of
the front Friday it appears there is a brief window where moisture
deepens up 700 MB, and low-level convergence associated with the
front may trip off a few showers Friday afternoon. POP coverage
for this feature to remain in the isolated category. The coolest
portion of the extended period is daybreak Sunday deep into the
40s. The mildest air will be felt Friday just ahead of the front
when we reach into the middle and upper 70s. The breeziest part of
the forecast period remains Friday late afternoon through evening
as robust cold air advection brings NW winds 15-25 mph. Higher
gusts to 30 mph may occur from the ICW to the beach corridor


As of 00Z...Elongated center of high pressure to extend west
across the area from the Atlantic. Basically looking at a repeat
of last night with clear skies and winds decoupling after the sfc
based inversion develops. Winds basically will be calm during the
pre-dawn hrs allowing fog development, especially across the
inland terminals. Will be more pessimistic with the fog inland
then at the coastal terminals with respect to horizontal vsby and
the low ceiling/vertical vsby. Daytime Wed will basically be a
repeat of Tue daytime with the sea breeze developing during the
midday and aggressively pushing inland. Will only indicate sct cu
with no vertical development expected given the isothermal layer
between 850mb and 700mb via latest progged soundings.

Extended Outlook...Thu morning, possible MVFR/IFR from fog and
low ceilings. Fri, possible brief MVFR in -SHRA and clouds.
Otherwise, remaining outlook is for vfr.


As of 10 PM Tuesday...High pressure over the western Atlantic
extends a ridge axis westward and across the Carolinas. Light
southerly seabreeze winds will turn offshore late tonight with a
weak landbreeze. Spectral wave data from the Frying Pan Shoals shows
a 14-15 second easterly swell dominates the sea state this
afternoon. Sea heights should average 2 feet south of Cape Fear, 3
feet to the north.

As of 3 PM Tuesday...The ridge of high pressure over the Carolinas
will begin to get squeezed from both the northwest and the southeast
this week, getting narrower and narrower until finally dissipating
late Thursday night. The culprit is a cold front and upper level
trough advancing toward the area from the west, and developing low
pressure east of the Bahamas which may become the next tropical or
subtropical storm Wednesday or Thursday. While any potential
tropical system will certainly remain too far offshore for any
direct impacts, the weakening ridge should allow our winds to turn
firmly northeasterly Thursday, but with wind speeds only around 10

As of 3 PM Tuesday...A strong cold front Friday may bring Advisory
conditions for small craft, mainly due to the expectation of gusts
of 25-30 KT late Friday, given cool air advection over relatively
mild waters. Additionally, seas will build to 5-6 feet along the
very out ribbon of the 0-20 NM waters. Winds on Saturday will
remain out of the NW but wind- speeds will diminish considerably.
Sunday WNW- NW 12 KT or less. By Monday the high will dip south of
the waters and WSW-W winds 12 KT or less is expected. Because of
offshore flow this period, lowest seas will reside inshore, with
appreciably higher sea heights across the outer waters due to
fetch distance physics.


As of 3 PM Tuesday...Exceptional amounts of water coming down the
Black, Cape Fear, and Northeast Cape Fear Rivers is causing periodic
coastal flooding in downtown Wilmington. Water levels as high as
7.37 feet MLLW occurred yesterday, with 7.22 feet MLLW at today`s
high tide. Tidal anomalies should slowly decrease here over the next
several days, but not before at least one more warning-level flood
event with Wednesday afternoon`s high tide. The Coastal Flood
Warning has been extended through 3 PM Wednesday. Note: Moderate
coastal flooding (a warning-level event) is defined as 6.7 feet MLLW
or higher at the Wilmington gauge.

Tide forecast/anomaly analysis:
Downtown Wilmington    High Tides  Tide  + Anom = Total Water Level
    Wednesday           12:21 AM   4.84  + 1.7  =  6.54 feet MLLW
    Wednesday           12:53 PM   5.31  + 1.6  =  6.91 feet MLLW
    Thursday             1:21 AM   4.66  + 1.4  =  6.06 feet MLLW
    Thursday             1:55 pm   5.14  + 1.3  =  6.44 feet MLLW


As of 3 PM Tuesday...Power remains out at the Lumberton, NC
airport. The emergency generator which had maintained power to
the LBT ASOS since Hurricane Matthew gave out last night.
Observations and climate data from Lumberton will remain missing
until power can be restored, and LBT TAFs will remain in a `AMD
NOT SKED UFN` mode until full metars flow.

Also due to Hurricane Matthew, the Georgetown, SC NOAA Weather
Radio broadcast remains off the air due to phone line issues. Our
technicians are working on getting a temporary phone line up and
running for this site as soon as possible.


NC...Coastal Flood Warning until 3 PM EDT Wednesday for NCZ107.


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