Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 290301

Area Forecast Discussion
National Weather Service Wilmington NC
1101 PM EDT SUN AUG 28 2016

A tropical airmass will affect the Carolinas for much of this
week. In addition, the tropics have heated up with Tropical
Depressions 8 and 9, and also Hurricane Gaston. While we don`t
have to worry about a direct influence from Gaston, the swell it
generates will affect the area coastline late tonight thru mid-
week, elevating the rip current threat. For depressions 8 and 9,
it will be a waiting game of whether these 2 depressions survive
the next 24 to 48 hrs. By the end of this week, a strong cold
front is expected to push across the Carolinas to well offshore.
Strong high pressure will follow, finally drying things out.


As of 1030 PM Sunday...No changes to the earlier forecast update.

As of 800 PM Sunday...The near term models, HiRes WRF and the RAP
and to a lesser degree the HRRR, all illustrate the demise of
convection over inland areas, ie. 1 county in from the coast and
continuing further inland, during this evening. Thus POPs will be
lowered to isolated chance for the night inland. However, pcpn
activity is progged by the near term models to further develop
over the adjacent Atlantic waters during this evening and pre-dawn
Mon hours. Occasionally will see this pcpn take a trajectory that
moves it onshore and inland. POPs to 40 to 50 percent will be
painted along the coastal counties and local Atl waters. Temps and
dewpoints were tweaked generally upwards by 1 to 3
degrees...especially across the coastal counties where onshore
winds having moved across low to mid 80s SSTS.

PWs have increased to 2+ inches across the entire ILM CWA, this
due to onshore winds thruout the atm column bringing in that
moistened tropical Atlantic airmass. Will need to monitor pcpn
intensity and amounts that could possibly result in changing the
Z/R relationship to tropical mode with regards to the KLTX 88D

Moderate risk of rip currents across all beaches Monday. May need
to upgrade that to High depending on how much Gaston Swell energy
makes it to the local surf. TD #8 progged to remain far enough NE
of the ILM CWA with no direct influence during its progged
movements. With long period Gaston Swell affecting the area
beaches late tonight and subsequent periods. Any waves from TD #8
will mesh within Gaston Swell along with the locally produced NE
to ene wind waves.


As of 300 PM Sunday...Tropical Depression Eight is projected to move
WNW towards the Outer Banks of NC on Monday while strengthening to
tropical storm status, making its closest approach to land on
Tuesday morning before recurving back to the NE on Tuesday
afternoon. Based on the projected track and development of this
system, impacts over land for our forecast area are expected to be
minimal with no watches, warnings or advisories expected. However,
there may be a heightened rip current risk along the coast. A moist
airmass and diurnal heating will encourage scattered convection on
both days, with highest chances along the coast. Dry air inland will
keep POPs and QPF in check for our northwestern-most counties.
Temperatures will be within a few degrees of seasonal norms through
the period.


As of 300 PM Sunday...A weak mid level pattern initially will give
way to mid level troughing by the weekend. This trough will allow
a cold front to move across late Thursday and take up residence to
our south. The latest guidance has shifted the front a little more
southward as well as the very dry mid level air. Not enough of a
change to warrant any changes to the forecast for the weekend
which include good chance pops across the south decreasing as you
move north. Wildcard remains what happens to AL99. There is at
least some hint of consensus (all of a couple of medium range
cycles) that the system forms in the Gulf of Mexico and moves
along the southeast coast possibly affecting our area Sunday and
Monday. Seems the best option is to maintain slight chance pops
which are basically climatology and wait it out. Warm temperatures
Wednesday and Thursday cooling slightly behind the front but lows
in the 60s may be difficult citing the lingering moisture.


As of 00Z...Showers and isolated thunderstorms on the wane attm.
Expect coverage over land to fall off to almost nothing soon.
However, showers and tstms may continue to develop offshore and
move towards the coast tonight. Have not included this in TAF as
confidence in a shower or storm reaching a coastal terminal
overnight is low.

There is the possibility of stratus tonight, but
it is not expected to be as widespread as last night. Some fog is
also possible, favored inland, through daybreak before a similar
day develops with NE to E winds around 10 kts and MVFR/VFR cigs
and scattered showers and isolated thunderstorms that will mainly
affect the coastal terminals.

EXTENDED OUTLOOK...Increasing chance of TEMPO sub VFR each day as
tropical moisture/shower potential increases through Tuesday. VFR
Wed/Thu. Shower potential increases again beginning Friday.


As of 1030 PM Sunday...Status quo across the local waters. No
changes needed to the previous update.

As of 800 PM Sunday...Based on latest obs from buoys across the
coastal and offshore waters, as well as local sites along the
immediate coast (OMR), have decided to increase the NE
winds overnight into subsequent periods. This a reflection of an
increased sfc pg due to ridging across the Carolinas from the
high over the NE States and the circulation associated with TD
#8. Basically, looking at NE 10 to 15 kt or just a solid 15 kt.

Significant seas will finally be influenced by the long period,
13 to 15 seconds, Gaston swell beginning late this evening or
during the pre-dawn Mon hours. At this time, the leading edge of
the dominant 13-15 second period Gaston swell extends from buoy
41025 to west of 41002. Local buoys, relatively speaking, 41108
and 41159 do indicate the 13-15 second period swell but its
height is too small for it to be the dominate wave like whats now
occurring at buoy 41025.

As of 300 PM Sunday...Tropical Depression Eight is projected to
move WNW towards the Outer Banks of NC on Monday while
strengthening to tropical storm status, making its closest
approach to land on Tuesday morning before recurving back to the
NE on Tuesday afternoon. Based on the projected track and
development of this system, impacts over the coastal waters are
expected to be minimal with no advisories expected. Winds will
generally remain in the 10 to 15 kt range through the period,
backing from the NE on Monday to N on Tuesday. Seas north of Cape
Fear in closest vicinity to the storm may peak at 3 to 5 ft Monday
night and early Tuesday before subsiding back to around 3 ft on
Tuesday night. Seas further south of Cape Fear will be lower.

As of 300 PM Sunday...A very weak pressure pattern will prevail
Wednesday into early Thursday leaving the sea breeze as the main
driver of winds. With warmer overnight lows the land breeze
shouldn`t be a factor. By Thursday afternoon a better defined
southwest flow ahead of a decent front develops. Speeds here should
be 10-15 knots. Northeast winds will develop Friday and pick up
a little on the intensity. Overall seas will be 2-4 feet.




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