Area Forecast Discussion
Issued by NWS Wilmington, NC-- Remove Highlighting --
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FXUS62 KILM 300126
Area Forecast Discussion
National Weather Service Wilmington NC
926 PM EDT MON AUG 29 2016
A warm and humid tropical airmass will remain in place through
much of the week across the Carolinas. A tropical depression over
the Atlantic will approach the Outer Banks through Tuesday.
Another tropical depression in the Gulf of Mexico should move up
through the coastal waters off the southeast coast on Friday while
a cold front drops down from the northwest. Cooler and drier high
pressure will build in behind the front over the weekend.
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
-- Changed Discussion --As of 815 pm Monday...The transition from diurnally driven
convection over land to the nocturnally driven convection over
the adjacent Atlantic waters will occur this evening. After
midnight, the convection will increase in coverage of the Atl
waters and will sporadically move onshore. Pops have been
re-aligned for late this evening thru the overnight, with the
highest pops along the immediate coast, dropping considerably
the further inland one goes. The hiest pops will be in the Good
Chance range. Will have to keep an eye on the rainfall amounts
and the possibility of changing the Z/R relationship given the
now persistent Tropical airmass. Current low temp fcst still aok
and see no reason to tweak at this time.
As of 300 PM Monday...Showers will diminish in areal coverage and
intensity with the loss of heating this evening. But with the
upper low still to our south some low rain chances will linger all
night along the coast. Low temps will be in the lower 70s and show
little geographical variation. Enhanced rip current threat
association with Gaston swells to continue.
-- End Changed Discussion --
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
As of 300 PM Monday...Upper low to our south weakens during the period
but a pronounced weakness in the height field will remain up the
coast. This will keep rain in the forecast with the highest chances
along the coast where both sea breeze and convergence resulting from
the onshore flow will provide lift. Wednesday may end up seeing a
weak low move up the coast, its roots in the convection that is now
associated with TD9. Temperatures will be very close to
.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 300 PM Monday...The mid level pattern will feature decent
troughing for the first part of the period then transitioning to
weak ridging by early next week. Regarding surface features, a
cold front remains on track to move across the area Thursday into
early Friday and drop well to the south by Saturday. Of course
what happens with TD nine remains a wildcard and guidance has
shifted once again to a more offshore solution. Once again a wait
and see strategy is the best course of action with perhaps more
drying than earlier forecasts. Also trended back on temperatures
slightly for the weekend as the cooler airmass will have more of
an impact with less moisture.
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
As of 00Z...Expect current batch of light rain and a few
thunderstorms to dissipate in the next hour or two, ending the
thread at terminals for the night. There is again the small
possibility of a shower or thunderstorm advecting on shore during the
night but the probability at individual taf sites is too low for
inclusion in the TAFs. Late tonight look for another round of low
stratus clouds (IFR) to form in the 08z-10z timeframe. Best
potential for br is inland. Cloud bases should lift above 1000 feet
around or shortly after 13z.
EXTENDED OUTLOOK...Chance of IFR/LIFR cigs during the early morning
hours Wednesday and Friday. Generally VFR Thu. Moisture increases
again Friday and Friday night with areas of MVFR possible in
-- Changed Discussion --NEAR TERM /THROUGH TONIGHT/...
As of 900 PM Monday...Raised a SCA for the ILM NC Waters. Raised a
SCEC for the ILM SC Waters. Tropical depression 8 to pass by to
the north of the ILM coastal waters tonight thru Tuesday. This
will result in a slight tightening of the sfc pg especially across
the ILM NC Waters. As a result, have increased the nne-ne winds
especially across the ILM NC Waters. Significant seas will be a
combination of Gaston 13 to 15 second period swell, TD #8 pseudo
swell in the 7 to 9 second periods and finally locally produced
wind driven waves at 3 to 5 second periods. The local wind driven
waves addition was negated earlier, but now its addition will push
significant seas up to 6 ft, ie. SCA criteria. Overall, the
dominate periods will fluctuate between Gaston 13 to 15 second
period swell and TD #8 7 to 9 second period pseudo swell.
As of 300 PM Monday...Gaston swell is being over-forecast in
height as even all the way out to 41013 waves are hesitant to
attain a height of 4 ft. Will leave SCEC up for northern waters
however as some higher waves may move in later this evening and
overnight. Otherwise we stay NE at 10 to 15 and generally 3 to 4
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
As of 300 PM Monday...WNA guidance shows a secondary swell front
from Gaston arriving Tuesday afternoon but likely only to the
tune of 1-2 ft. This may still be enough for a continuation if not
an expansion of the cautionary headlines for Tuesday. Wind remains
onshore Wednesday though a weak surface low passing by may modify
that slightly. Headlines will no longer be in effect as the Gaston
LONG TERM /THURSDAY THROUGH SATURDAY/...
As of 300 PM Monday...Somewhat of a weak pressure pattern for
Thursday before a cold front moves across early Friday. Expect
mostly south to southwest winds of 10-15 knots leaning mostly to
the lower end of the range. Northeast winds will set up shop after
this with the gradient increasing to allow a range of 15-20 knots
by Saturday. All of this is dependent on the eventual track and
intensity of TD Nine. Significant seas will generally follow the
winds increasing from 2-3 feet early to 3-5 feet late.
-- End Changed Discussion --
SC...High Rip Current Risk through Tuesday evening for SCZ054-056.
NC...High Rip Current Risk through Tuesday evening for NCZ106-108-
MARINE...Small Craft Advisory until 8 PM EDT Tuesday for AMZ250-252.