Area Forecast Discussion
Issued by NWS Wilmington, NC-- Highlight Changed Discussion --
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FXUS62 KILM 280836
Area Forecast Discussion
National Weather Service Wilmington NC
436 AM EDT Wed Sep 28 2016
A cold front approaching from the west will stall through mid-
week before moving across the area Thursday into Friday. Dry high
pressure will build into the area by the weekend.
.NEAR TERM /THROUGH TONIGHT/...
As of 330 AM Wednesday...Todays highlight will be the potential
for thunderstorms to reach strong to possibly isolated severe
status from midday thru well into this evening. Highlighted this
possibility in the Hazardous Weather Outlook.
Instability across the area has been lacking the past few days
which that will change. The expansive closed upper low will cut
off and drop from the southern Great Lakes to the central
Appalachians by early Thu. Flow aloft will become cyclonic with
unidirectional SW winds with increasing speeds with height. Closer
to the coast, low level winds will be more southerly. PWs increase
to around 1.75 inches along with an influx of widespread upper 60s
to low 70s sfc dewpoints, further enabling instability. POPs will
peak at 50 percent over land today into this evening, and again
during the pre-dawn hrs across the eastern FA and adjacent local
Atlantic Waters. Embedded mid-level s/w trofs rotating thru will
partially affect the fa, mainly later tonight as they move from
the Gulf of Mexico today to partially across the eastern portions
of the FA late tonight. For max/min temps, once again above climo
norms from 1 to possibly 2 categories above the norm, especially
night time lows.
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
-- Changed Discussion --As of 345 AM Wednesday...Of the 2 days, Thu will be the wetter of
the 2 and exhibit the higher POPs. The main feature will be the
cutoff low making its furthest southern positioning across the
Central Appalachians. Thursday will feature embedded and stronger
mid- level s/w trofs rotating around this cutoff low. The 1 Thu
morning moves NE of the FA with the eastern 1/3 to 1/2 seeing
ongoing convection at the start of the day, moving out of the FA
by late morning. The next s/w rotating around and closer to the
cutoff low, will help push a dry slot across portions of the FA
late Thu aftn and night. With it not entirely thru the FA, will
keep a POP for the far eastern portions of the ILM CWA Thu night
into Fri. Finally, the models indicate the dry slut will finally
shunt the remaining moist air off the Carolina coasts by late
Friday. Improving wx conditions across the FA during Fri into Fri
night. Max/Min Temps, stayed closer to a consensus with a lean
toward the MET mos guidance based on its decent performance the
past couple days.
.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 3 AM Tuesday...Despite the fact that the long term begins with
an impressively large cutoff to our west the weather will be pretty
quiet. The reason for this is that we will be in the dry slot of the
occluded surface low to our NW and the deep moisture will be off the
coast. Sunday and Monday as the weakening front pushes through some
of this moisture may get drawn back to the coast for some minor rain
chances-all while temperatures remain close to their seasonable
norms. The front washes out by Monday leaving behind a weak surface
pattern while mid level heights build. There will still be no real
forcing for precipitation and no low level thermal advection to
change temperatures much from the values earlier in the period.
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.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
As of 06Z...Light and variable winds setting up though inland
terminals may see a light southerly breeze through the night. Even
so, some MVFR fog possible just about anywhere with plentiful low
level moisture but mid level cloud deck should prevent any further
reduction in flight category. After sunrise VFR expected and any
shower or thunderstorm activity too isolated to warrant anything
other than VC save for maybe LBT where coverage could wind up a bit
EXTENDED OUTLOOK...Scattered SHRA/TSRA through Thursday. A cold
frontal passage late Wednesday into Thursday. Primarily VFR
expected Friday through Sunday.
-- Changed Discussion --NEAR TERM /THROUGH TONIGHT/...
As of 330 AM Wednesday...Sfc pressure pattern and gradient will
begin to reflect the input from the upper closed to cutoff low
dropping to the Central Appalachians by late tonight. Southerly
winds at 5 to 10 kt today will become SW 10 to 15 kt tonight. This
reflection of the sfc cold front still hung up across the western
portions of the Carolinas. Significant seas will run 2 to 4 ft,
with the majority of the seas comprised by a 1 to 3 foot ese
ground swell at 11 second periods. The 4 footers will primarily
affect the waters from Cape Fear northward.
Instability has been questionable across the FA the past few
days. However, this will change. In addition, an embedded midlevel
s/w trof will push from the Gulf of Mexico today, NE and across
the area waters later tonight. Expect convection to be more
isolated to widely scattered today becoming scattered to areas of
pcpn later tonight.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 345 AM Wednesday...Sfc pressure pattern and a tightening-some
of the gradient, will result in SW winds at 10 to around 15 kt
thru this period. Significant seas will run 2 to 3 feet with 4
footers possible Wed and Thu when winds will be closer to 15 kt
sustained due to the semi-tightened sfc pg. Wavewatch3 and local
Swan keeps the ESE 11 second period ground swell affecting the
local waters but with some degradation. Local wind driven waves at
4 to 6 seconds will become the more dominant feature of the
significant seas by late Thu thru Friday.
The sfc cold front will finally push to the Carolina coasts
during Friday, and stalling just offshore the ILM Waters Friday
night. The dry slot or tongue will push across the waters late
Friday ending the threat for showers and thunderstorms.
LONG TERM/SATURDAY THROUGH SUNDAY/...
As of 3 AM Tuesday...A weakening cold front running parallel to the
coast will only slightly shift through the period moving from just
onshore to just offshore. It`s parent surface cyclone will be well
occluded and thus deprived of its energy source and so the whole
system will feature a baggy and poorly defined pressure pattern.
This is good news for most mariners though as winds will be quite
light and somewhat variable through the period. Seas will be
slightly elevated above what such slack winds would otherwise
support since spectral wave bulletins show a myriad of wave
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