Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 141358
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
958 AM EDT Fri Aug 14 2020

.SYNOPSIS...
Unsettled conditions will prevail through the weekend, as a
frontal boundary slowly approaches, with a semi-tropical air
mass over the area. Slightly drier air is expected early next
week behind the front. Unsettled weather returns by mid-week as
boundary stalls near coast.

&&

.UPDATE...
Fog lifted leaving fairly widespread blanket of low clouds
across inland areas by mid morning. Westerly winds were pushing
these clouds toward the coast and expect them to transition
into a decent area of stratocu. Made minor adjustments to the
forecast, mainly for pops and clouds. Expect a little later
start with convection due to cloud cover this morning, but
abundant moisture, differential heating, lingering trough and
the sea breeze should all aid in initiation. The westerly flow
should keep best convergence along sea breeze close to the
coast.

&&

.NEAR TERM /THROUGH SATURDAY/...
GOES onboard PWAT sensors detecting a stream of precipitable
water content in excess of 2 inches, with slightly drier air
bottled behind the mountains from ern TN to ern VA. GOES low-
level water vapor and mosaic-radar reflectivity overlay show
oceanic TSTMs remain attendant around a disturbance east of Cape
Lookout. This feature will move NE in time, as an upper trough
to the west, shifts east over the TN valley, increasing SW winds
aloft locally.

Overall expecting a lull in convection this morning, until re-
newed updrafts spawn convection this afternoon. Weak subsidence
may be in play over the area with departing upper feature to the
ENE. A west flow in the column may inhibit storms moreso inland
today, but could increase coastal convergence. Have lowered pop
values into scattered range today, as lift triggers will be
diurnal and weak, joined by a downslope flow.

Semi-tropical air mass stays through Saturday. The low-level
flow late Saturday begins to back toward south as a surface low
and upper trough to the west approach the coast, also providing
a slight boost in upper support. This should lead to better rain
chances Saturday compared to today, as winds aloft and low-
level convergence increase.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
With a 500mb shortwave moving across the area Saturday night,
and a surface front approaching from the west, have likely pops
in the forecast for Saturday night through Sunday. Moderate
rainfall possible with high precipitable water values still in
place. Highs Sunday in the upper 80s, aided by increased clouds
and precip. Dry air moves in behind the front Sunday night,
decreasing rain chances from west to east overnight. Lows near
75 Saturday night will drop to low 70s Sunday night.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
Abundant dry air aloft in place Monday through early Tuesday as
deep north-northwest flow develops behind exiting front/trough.
This will help keep any convection that may develop isolated,
with low end chance pops in the forecast Monday and Monday
night. Mid level high pressure offshore to the southeast
strengthens Tuesday into Wednesday, combining with deepening
upper level trough over eastern US to allow deep south-southwest
flow to return to the area and increase moisture again. At the
surface, a second boundary moves into the area on Tuesday and is
forecasted to stall near the coast through end of the week.
Will see increase in pops beginning Tuesday, with Wednesday and
Thursday currently carrying highest chances. Temps near normal
for the long term, with highs in the upper 80s and lows near 70.

&&

.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
LIFR/IFR stratus and fog at the inland TAFs and VFR at the coast TAF.
Inland stratus and fog will dissipate by 15 UTC. This could delay
convection until after 18 UTC. IFR/LIFR conditions can be expected
around thunderstorms. IFR conditions can be expected as stratus and fog
are possible again after 06 UTC especially at the inland TAF sites.

Extended Outlook...Scattered to numerous SHRA/TSTMs this
weekend as a frontal boundary approaches the coast. Less TSTMs
early next week as slight drying occurs in wake of a cold front.

&&

.MARINE...
Through Saturday..

SW winds will reach moderate range, as low pressure inland
shifts east, and helps to tighten the SW gradient a little bit,
resulting in 10-15 kt SW winds, with occasionally higher gusts.
Winds and seas will be higher in and near TSTMs this period,
scattered in coverage, and isolated waterspouts are expected
today and again early Saturday, radar updates are encouraged.
Winds in the afternoon near shore may back to S with gusts to 18
kt at times. Seas will be comprised of moderate SSW wind-sea
every 4-5 seconds, and SE waves 1-2 feet every 8-9 seconds.
Cloud to sea water strikes will remain a hazard this period as
well. Never attempt to approach a waterspout, swirling winds can
cause injury by flying debris. A waterspout can capsize a small
craft.

Saturday Night through Tuesday..

Southwest flow 10-15 kts Saturday night and Sunday will veer to
northerly by Monday morning behind an exiting front. Winds
become light, 5 kts or less, and variable Monday through Tuesday
as pressure gradient relaxes, before light SE flow develops
Tuesday night. Seas 3-4 ft Saturday night through Sunday will
relax to 2-3 ft Sunday night through Tuesday, combination of
weakening S wind wave and 1-2 ft 9-10 s SE swell. Could see an
additional weak SE swell arriving from TS Josephine late Monday
into Tuesday. Storms likely over coastal waters Saturday night
and Sunday, before chances decrease Sunday night through early
Tuesday as dry air moves in aloft.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.

&&

$$
SYNOPSIS...ILM
UPDATE...RGZ
NEAR TERM...MJC
SHORT TERM...VAO
LONG TERM...VAO
AVIATION...RH
MARINE...MJC/VAO



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