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Area forecast discussion 
National Weather Service Wilmington NC
638 am EDT Tuesday Sep 16 2014

Synopsis...
a cold front will push offshore today. High pressure will extend
down into the Carolinas from the north behind this
front...providing Fall-like weather for the remainder of the week.

&&

Near term /through tonight/...
as of 6:15 am Tuesday...no changes to the forecast with the latest
update. Previous discussion follows:

At the upper levels a flattish long wave trough will deepen
through the near term as a series of weak disturbances transit
overhead. The strongest disturbance will move through this
morning. At the surface a rather weak and amorphous pressure
pattern makes it difficult to discern exact frontal placement and
thus subsequent frontal motion but the general scenario is fairly
clear. A nearly stationary front across the deep south seems to be
in the process of dissipating while lifting back north as a cold
front approaches from the northwest. A consensus of guidance
merges the fronts today over the eastern Seaboard...keeping a
broad and weak pressure gradient in place through the daylight
hours with little in the way of significant isentropic lift. Post
frontal passage high pressure builds in more assertively overnight although
cold advection will trail well behind this feature.

Not overly impressed with precipitation chances today. Model
soundings show a marginally to moderately unstable airmass today and
convective indices show isolated to scattered convection is a
possibility...but moisture profiles show middle levels are on the dry
side and aforementioned lift associated with frontal passage not very strong.
Best shot at substantial convection looks to be this morning as an
upper disturbance skirts the southern portion of our County Warning Area. Will be
keeping probability of precipitation in the fairly modest 20 to 30 percent range for
today...with chances trailing off after midnight as dryer and more
stable air filters in Post-fropa.

Temperatures will be quite seasonal...with model consensus giving
US highs in the middle 80s and lows in the middle to upper 60s.

&&

Short term /Wednesday through Thursday night/...
as of 300 am Tuesday...middle level troughing will dominate the eastern
third of the U.S Wednesday through Friday. At the
surface...residual low pressure just to the south of the area will
keep things unsettled Wednesday. Lift will also be enhanced a
little by the middle level trough. By Thursday...high pressure takes
firm control as it builds down the East Coast. The GFS is showing
light quantitative precipitation forecast and this may occur in the form of drizzle or light rain
showers as there is just enough isentropic lift...speed
convergence to warrant. With soundings relatively dry
however...precipitable water values are about 1.25 inches...do not
expect anything significant. Temperature guidance is stable with
highs in the 80s both days...a degree or two warmer Wednesday and
overnight lows...moderated by the winds and expected broken to
overcast skies in the lower to middle 60s.

&&

Long term /Friday through Monday/...
as of 300 am Tuesday...medium range guidance remains in good agreement
on the scenario at the middle levels through the period. The main
belt of westerlies shows convergence along the Great Lakes and
upper Midwest regions for Friday and Saturday. The result is a
massive surface high that extends well down into the southeast.
This pattern breaks down Sunday and Monday as ridging develops in
The Four Corners region with a decent middle level trough moving
through the Ohio Valley. This allows another moisture starved
front to move across the region Monday and I have maintained the
mention of showers and thunderstorms. Regarding probability of precipitation for Friday
into the weekend...only light showers and or drizzle is expected
mainly offshore. No changes to the temperature forecast.

&&

Aviation /12z Tuesday through Saturday/...
as of 12z...another day with a weak gradient...mainly light and
variable winds expected. A cold front...really the same front that
has been hanging around for over a weak...will drop in tonight.
There will be convection out ahead of it...but rather low confidence
on the amount of coverage we will see today. Think most of the
convection will occur this afternoon...with a small batch this
morning over southeast North Carolina. Ceilings are going to bounce
around this morning...improving to VFR at all terminals by late
morning. Tonight...front pushes through the region with winds
shifting to northeast...along with Post frontal stratus.

Extended outlook...Post-frontal MVFR ceilings may develop Wednesday as cooler
air wedges into the region. Early morning MVFR/IFR ceilings possible on
Thursday. Gusty northeast winds expected Friday/Sat as the cool air wedge
strengthens over the Carolinas.

&&

Marine...
near term /through tonight/...
as of 6:30 am Tuesday...no changes to the forecast with the latest
update. Previous discussion follows:

A weak pressure pattern will prevail through the near term period.
Winds today and tonight will stay generally under 10 kts...with
seas not straying far from their present 2 to 3 feet range.

Short term /Wednesday through Thursday night/...
as of 300 am Tuesday...generally a northeasterly component to the
winds will prevail Wednesday. The winds will be light...ten knots
or less and there may be a little veering due to sea breeze
effects. The northeast flow will increase in magnitude a bit
Thursday with a range of 10-15 knots. Seas will be 2-4 feet with
an increase to 3-5 feet by Friday morning.

Long term /Friday through Saturday/...
as of 300 am Tuesday...the strong northeasterly flow will continue
Friday with wind speeds of 15-20 knots. Significant seas will be
representative of the strong wind fields with 3-7 feet and likely
small craft advisories. For Saturday the winds diminish to 10-15
knots. Seas however remain elevated as a significant swell component
is added to the spectrum.

&&

Ilm watches/warnings/advisories...
SC...none.
NC...none.
Marine...none.

&&

$$

Synopsis...shk
near term...rek
short term...shk
long term...shk
aviation...43
marine...rek/shk

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