FXUS62 KILM 200444

Area Forecast Discussion
National Weather Service Wilmington NC
1244 AM EDT Fri Oct 20 2017

Mostly clear skies and seasonably warm temperatures are expected
into the weekend, as a dry upper ridge builds across the
region. An approaching strong cold front will bring showers and
thunderstorms early next week. Much cooler temperatures are
forecast in the wake of the front beginning Wednesday.


As of 900 PM Thursday...High pressure consolidating over
eastern TN will gradually shift east-northeast Fri as it
slowly weakens. A weak shortwave has exited the coast and is
being replaced by a mid-level ridge through Friday. Winds will
be light and variable through the period due to a very weak
gradient in place. Deep dry air and light to calm winds
overnight will lead to strong radiational cooling with inland
cold spots dipping to the mid 40s. Along the coast, lows will
be in the lower to mid 50s. Very dry air lingers in the region
Fri with precipitable water values peaking around 0.50 inch in
the afternoon. Highs on Fri will end up a few degrees warmer
than today, mainly due to building heights/thickness and further
air mass modification. Flow remains northerly through just
about the entire column so there is no real warm advection to
speak of. Relaxed gradient will allow for development of weak
afternoon sea breeze which may temper highs along the coast,
but do not expect any cloud development.


As of 300 PM Thursday...Mid to upper ridge up the southeast
coast and surface high pressure to our north will both shift
east through the period. Overall a very light NE flow will veer
around becoming more easterly through the period. This will
allow for an increase in low level moisture basically late Sat
into Sat night. This should bring some low clouds mainly over
northeast SC or some fog elsewhere, mainly near the coast.
Dewpoint temps will increase from near 50 to 55 Fri night to 55
to around 60 by daybreak Sun. The strong subsidence inversion
will slowly erode through the period but not enough to allow for
any pcp or for that matter much in the way of cloud. The dry
air in place will allow for a large diurnal swing, but slightly
dampened Sat night with an increase low level moisture. Overall
mainly clear skies and very light winds leading to decent
radiational cooling. Overnight lows will be 50 to 55 Fri night
and 55 to 60 Sat night most places while bright Oct sunshine
will bring temps up close to 80 Sat aftn.


As of 300 PM Thursday...the upper level pattern continues to
show high pressure breaking down and a large scale trough moving
to the eastern half of the United States by Tuesday. This is
slower than the previous run. At the surface the frontal
boundary is slower with the GFS bringing the frontal boundary
into the area Tuesday night. The ECMWF is even slower with the
boundary pushing off the coast Wednesday morning.

Precipiation chances start late Sunday night with isolated
showers then chances increase to likely on Tuesday with the
frontal passage.

High temperatures will be around 80 degrees on Sunday and
Monday but with the frontal passage will see temperatures
falling into the upper 60s to middle 60s by Wednesday and
Thursday. Lows on Sunday night will be in the lower to middle
60s but will fall into the middle to upper 40s by Wednesday


As of 06Z...Given the low dewpoint depressions, calm wind and
clear skies, have included a tempo group for MVFR fog at all
the TAF sites, mainly in the 08-12z time frame. However, at
KCRE, will forecast prevailing MVFR fog through 12z with tempo
IFR fog/stratus. After 12z, skies will be SKC with light N
winds, becoming E to SE less than 10 kt at the coast after
17-19z due to a developing seabreeze. KLBT has not reported an
observation in the last few hours and will append AMD NOT SKED
to the TAF with the 06z issuance.

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


As of 1000 PM Thursday...High pressure over eastern TN will
shift east-northeast Fri. Gradient over the waters continues to
relax with speeds under 10 kt overnight. Flow remains north to
northeast through the period, and gradient remains weak with
speeds 10 kt or less Fri. Winds may veer to east or even
southeast later in the day in response to development of weak
sea breeze. Seas will be 2 to 4 ft overnight and 2 to 3 ft on
Fri with an easterly swell around 9 seconds slowly decaying.

As of 300 PM Thursday...High pressure to our north will shift
east through the period. Overall a very light NE flow will veer
around becoming more easterly through the period, remaining less
than 15 kts. Expect a slight chop Sat aftn as winds spike up
and become more on shore, but overall benign seas expected
mainly around 3 ft or less.

As of 300 PM Thursday...High pressure over the waters will
weaken and shift offshore. This will allow for veering of the
winds with a southerly wind by Monday. Seas will be 2 to 3 feet
on Sunday and will slowly increase by late Monday to 3 to 4 feet
as the winds slowly increase ahead of front that will approach
the waters late Tuesday.





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