Area Forecast Discussion
Issued by NWS Wilmington, NC
FXUS62 KILM 300241
Area Forecast Discussion
National Weather Service Wilmington NC
1041 PM EDT Thu Sep 29 2016
A stationary front will waver along the coast through this
weekend. Periods of showers with an isolated thunderstorm are
possible along this front. Weak high pressure will build in
early next week. Hurricane Matthew may bring increasing waves
by the middle of next week.
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
As of 1030 PM Thursday...Except for a single shower just north of
Marion, SC, the radar is clear across the ILM forecast area. This
should change by midnight as an upper level disturbance currently
moving north across coastal Georgia reaches the area. The region
of deep lift ahead of this feature should have around 1000 J/kg
of elevated instability to work with, assuming a parcel lifted
from around 2000-3000 ft AGL. Activity should cross the Santee
River by midnight, working its way northeastward to Cape Fear by
4-6 AM. Locally heavy rainfall due to rather slow cell movement
and high precipitable water values should be the main threat with
In the meantime, we have an unusually humid airmass for this late
in the year across the Carolinas. A nearly stationary front
extends from near Augusta, GA to Columbia, SC to Hickory, NC and
is actually visible on satellite imagery as a narrow line of low
clouds. In areas where rain fell today and skies have cleared,
areas of locally dense fog have developed, particularly around
Whiteville and Elizabethtown. This fog will probably be with us
for at least the next 3-4 hours, however increasing cloudiness
with the incoming disturbance may destroy the ideal radiational
cooling conditions we are currently experiencing, making fog more
of a "patchy" to "areas" event by late tonight.
Forecast lows have been bumped down a degree or two where
radiational cooling is currently ongoing. This gives mainly upper
60s inland with lower to middle 70s confined to areas within 10-15
miles of the coast.
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
As of 345 PM Thursday...Little change in the synoptic setup into the
weekend as bowling ball of the upper low spins slowly across IN/KY
before lifting into OH late in the period. At the surface, a very
slow moving cold front will push eastward, likely finally crossing
offshore Friday night before stalling once again. With diffluence
remaining east of the upper low, and low level confluence likely
persisting along and east of the boundary, more convection with
periods of heavy rain is forecast Friday. The best chance for
rainfall will again be the eastern third of the CWA where mid-level
RH remains elevated despite a very dry punch within the dry slot
working into the Pee Dee. This creates 2 distinct air-masses across
just the local CWA, with PWATS forecast to drop below 1 inch well
inland, while remaining at 1.5-1.75 near the coast, and inland
counties may finally have a dry day Friday. By Saturday, most of the
CWA is forecast to get into the drier air, but once again the
immediate coast may still see no relief from this humid airmass with
more showers/tstms possible along the coast.
Highs both Friday and Saturday are forecast to be slightly above
climo, low 80s, but will be heavily impacted by clouds and rainfall.
Mins inland will drop into the upper 50s/low 60s both nights within
that drier air mass, but will remain near 70 at the coast.
.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 3 PM Thursday...Incredibly the relatively sharp west to east
precipitable water gradient remains in place across NE SC/SE NC much
of the extended period before the potential of tropical moisture
late next week. In essence this brings a sensible weather forecast
of chances for showers near the coast and very little along the far
interior zones. This in part due to the dry mid-level air wrapped
around the large upper low to the west, and the remnant presence of
dry air aloft across the area even as the low pulls away from the
region on Sunday. Even so a chance of showers will prevail along
the eastern 1/3 of the forecast zones days 4-7 with isolated TSTMS
favored nocturnally over the coastal waters, or a sea breeze pop up
in the middle afternoon. Temperatures to run near to a bit above
normal, especially for the minimums this period. Tempering of
maximum temperatures days 6 and 7 is attributed to increasing NE flow
across the area, but about normal max temp readings for early OCT.
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
As of 00Z...Upper low still nearly stationary, with a weak
surface front over our CWA. Look for dying convection over the
next several hours. Showers could briefly affect the coastal
terminals, with VCSH sufficing for now. Overnight, some light fog
is possible, briefly IFR at LBT. A coastal shower cannot be ruled
out along the coast toward morning. Friday, more of the same with
convection becoming scattered, most numerous around or just after
EXTENDED OUTLOOK...Primarily VFR. Isolated to scattered afternoon
showers through much the period, although limited in strength and
coverage due to dry air aloft.
NEAR TERM /THROUGH TONIGHT/...
As of 1030 PM Thursday...A front remains stalled across the
central Carolinas this evening, stretching from just east of
Augusta, GA to just west of Columbia, SC to near Hickory, NC.
Southerly winds continue across the coastal waters, and these
winds should continue overnight as the front remains inland. An
upper level disturbance moving northward across coastal Georgia
will probably bring scattered showers and t-storms back into the
area after midnight. Activity will reach the Cape Fear area late
tonight and may continue into the daylight hours Friday morning.
Seas average 3 feet mainly in southerly wind waves with 5-6 second
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 345 PM Thursday...A cold front will be west of the waters
Friday before wavering across or potentially still just inland on
Saturday. This creates predominantly S/SW winds of 10-15 kts on
Friday, backing to the SE around 10 kts on Saturday, again dependent
on where the front stalls. A period of variable winds is possible
late Friday into Saturday as the front drifts into the vicinity, but
speeds will be light during that time. Seas will hover around 3 ft
both Friday and Saturday with a low amplitude 9-10 sec SE swell and
2-3 ft 5 sec southerly wind wave comprising the spectrum.
LONG TERM/SUNDAY THROUGH TUESDAY/...
As of 3 PM Thursday...This period will be marked by 3-5 foot seas
and highest seas offshore, but elevated wave heights may
gradually arrive after Tuesday due to increasing swell from
Hurricane Matthew. No advisories expected through Tuesday.
Isolated showers and TSTMS can be expected this period and radar
updates are encouraged.