Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 181928
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
328 PM EDT Fri Aug 18 2017

.SYNOPSIS...
High heat and humidity will continue into Saturday with
scattered showers and thunderstorms ahead of a cold front. This
front will stall in close proximity to the coast during the
weekend before dissipating Monday. High pressure will build
across the area Tuesday and Wednesday. Another cold front will
approach from the northwest Thursday.

&&

.NEAR TERM /THROUGH SATURDAY/...
As of 300 PM Friday...The HRRR continues to show almost no
convection over the forecast area. When the HRRR does not want
to produce convection you know it will be hard for it to
develop. A few showers and thunderstorms are still possible
along the coast mainly north of Little River. The heat continues
to be a factor for this afternoon with heat indices in the 105
to 108 range.

Models continue to show a cold front moving into the eastern
Carolinas on Saturday and stalling along the I95 corridor. Models
have backed off on the rain percentages slightly and will go with a
30 to 50% chance of showers and thunderstorms. The coverage is
expected during Saturday afternoon. High temperatures are expected
to be a few degrees cooler and the heat indices overall will range
just below heat advisory criteria.

With the new moon on Monday the tides are becoming a little higher
and there is a threat of minor coastal flooding downtown tonight
between 7 and 9 PM.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 300 PM Friday...A cold front makes a run for the coast
but comes against the sea breeze and should keep a few lingering
showers into Sat evening close to the coast. The steering flow
is W-SW up to 15 kts or so and therefore any storms will move
off to the E-NE through the evening, basically off shore.
Expect diurnal heating to cut off and any convection to
dissipate into Sat night.

The dynamics associated with mid to upper trough helping to
give the front a push will lift off to the northeast through the
latter half of the weekend. Ridging tries to build in aloft with
enough subsidence and dry air to keep pcp mainly along the
coast or offshore on Sun. Looks like best moisture will be off
the coast with pcp water values dropping from 2 inches in
isolated spots along the coast in late day convection on
Saturday, down to 1.5 inches or less Sat night into Sun. The NAM
is a little more bullish bringing moisture back on shore as
Bermuda High builds westward. Overall looks like iso to sct
convection is possible along sea breeze as it pushes inland on
Sunday. Will keep lower end PoPs for Sunday then dissipating
into the evening and increasing again toward Mon morning as
boundary and moisture get a nudge back on shore.

Heat indices will be much lower on Sunday inland and probably
will only reach near 100 along the coast with dewpoint temps
down near or below 70 west of I-95 and closer to 75 Sun aftn.
It will still be very warm on Sunday with plenty of sunshine
especially inland with temps reaching into the 90s. Lows will
be in the 70s Sun night, but about 5 degrees lower than
previous nights.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
As of 300 PM Friday...A flat mid-level ridge will extend from the
Atlantic across the Carolinas Monday-Tuesday, then get suppressed
south as a trough carves out across the Eastern seaboard for the
latter half of the week. With no real airmass change evident in
guidance until perhaps Thursday, precipitable water values will
hover around 2 inches until then. Scattered pulse showers and
thunderstorms are expected each afternoon and evening Monday through
Wednesday, with the highest chances Wednesday night through Thursday
when convection becomes organized along and ahead of a frontal
boundary. As usual in the extended period, and especially in August,
there is a great deal of uncertainty with timing the front and
determining how far south it will push. Will hang on to higher PoPs
across the southern CWA on Friday to account for that.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
As of 18Z...Isolated convection developing along the coast mainly
impacting KILM early. Other possible VCTS mainly at the coastal TAF
sites. A cold front will stall near KLBT and KFLO sites in the
morning so MVF conditions for BR are expected. Winds are expected to
be from the southwest at 10 to 12 knots this afternoon and less than
8 knots after 00 utc at all sites.

Extended Outlook...Scattered TSTM Sun through Wed. Flight
restrictions will be possible in early morning stratus/fog
Sun-Wed.

&&

.MARINE...
NEAR TERM /THROUGH SATURDAY/...
As of 300 PM Friday...At this time there are south winds along
the beaches due to a mature sea breeze circulations. Farther off
the coast outside the circulation, winds will be from the
southwest. Currently, wind speeds are running between 15 and 18
knots and seas on average are around 3 feet. With a cold front
approaching and stalling inland, winds speeds over the waters
will be 14 to 18 knots overnight and will slowly weaken on
Saturday with the front stalling. Seas are expected to run 3 to
4 feet tonight and fall off to 3 feet late Saturday afternoon.

SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 300 PM Friday...A front will make a run for the waters but
should stall upstream of the waters Sat and then slowly begin
to dissipate late in the weekend. Winds will diminish Sat night
down to 10 kts or so by Sun morning. Expect lighter more
westerly winds on Sunday as front remains nearby. Looks like
convection could be focused moreso off the coast then inland.
Seas will subside down to 3 ft Sun, diminishing further, to
around 2 ft or less by Mon morning. Higher winds and seas will
be possible in and near thunderstorms.

LONG TERM /MONDAY THROUGH WEDNESDAY/...
As of 300 PM Friday...A benign pressure field across the waters will
keep winds 10 knots or less Monday and Tuesday, as a weak Bermuda
high pressure remains in place off the coast. Winds will begin to
pick up out of the southwest by Tuesday afternoon as a surface
trough takes shape across the Carolina piedmont. Shower and
thunderstorm activity is expected to remain isolated to widely
scattered over the waters in a general southerly flow through the
period.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...Heat Advisory until 6 PM EDT this evening for SCZ017-023-024-
     032-033-039-053>056.
NC...Heat Advisory until 6 PM EDT this evening for NCZ087-096-099-
     105>110.
     Coastal Flood Advisory from 7 PM to 9 PM EDT this evening for
     NCZ107.
MARINE...None.

&&

$$

NEAR TERM...DRH
SHORT TERM...RGZ
LONG TERM...CRM
AVIATION...DRH



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