Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 030543
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
143 AM EDT Mon Aug 3 2020

.SYNOPSIS...
Tropical Storm Isaias will begin affecting the region late
Monday as the storm approaches the Carolinas. Impacts will
continue into early Tuesday before the storm moves north of the
area. Typical warm and humid summer weather will return with a
chance of afternoon thunderstorms each day.

&&

.UPDATE...
Isolated inland showers have dissipated. Atlantic showers moving
northwestward well in advance of Tropical Storm Isaias will
begin to push onshore late tonight. Dry weather is expected this
evening, then PoPs have been adjusted slightly downward inland
and across North Carolina overnight. No significant changes have
been made to winds, sky, or temperatures.

&&

.NEAR TERM /THROUGH TUESDAY/...
Weak high pressure system will keep mostly dry conditions over the
region today with hot and humid conditions.  Heat indices today are
not quite as hot with lower dew points across the region, but values
still in the upper 90s to lower 100s will create heat illness
symptoms for those sensitive to heat and with long outdoor exposure
times.

Biggest concern for Monday into Tuesday is the arrival of Tropical
Storm Isaias.  Anticipated rainfall has increased slightly into the
2 to 5 inches range, while some areas could see increased amounts to
6 inches in locally heavier rainfall bands.  Some tornadoes are
possible, especially Monday afternoon/night into Tuesday morning
with the approaching storm.  Tropical storm force winds are possible
starting Monday evening into Monday night through Tuesday morning.
With a more westward track as of this writing, increasing wind speed
potential exists with locations seeing between 45 and 55 mph with
gusts up to 70 mph at times.  For coastal locations, beach erosion
and storm surge flooding is also possible with water reaching
between 1 and 3 feet above ground level.  The storm will also bring
high chances for dangerous rip currents today through Tuesday for
area beaches.  The storm exits the region by Tuesday afternoon, and
conditions area wide should begin to improve with lessening winds,
light rainfall, and improving conditions along the coast.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
Sharp mid-level trough will linger west of the area through Wed
night. deep southwest flow will maintain tropical moisture across
the region. Not expecting much of the way in convection Tue night
(cannot rule out some nocturnal marine convection) given the post
Isaias subsidence and lingering westerly flow in the mid levels.
Convection appears much more likely Wed with deep moisture lingering
over the area and the sea breeze and Piedmont trough generating
afternoon and evening storms. Could be a weak shortwave south of the
area Wed afternoon injecting some weak PVA into the local area,
although confidence in the shortwave timing is low. Convection will
gradually weaken through late evening, although convection may
develop offshore. Timing/location of the aforementioned shortwave
wave may impact potential for offshore convection Wed night. Highs
near climo on Wed with lows above climo.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
Mid-level trough axis west of the area late in the week will start
to fill as it drifts east for the weekend. Weak high pressure drifts
across the area from the west midweek, setting up offshore for
Sat/Sun. A weak front moves into the area late in the week, but it
may become indistinguishable from the Piedmont trough. Lack of any
mid-level drying and presence of surface features will support
diurnal convection each day. This is pretty typical of summer in the
Carolinas although coverage may be higher than normal given the
abundance of deep moisture. Highs will be near climo with lows a
little above climo.

- Afternoon storms expected each day, coverage will be 40% to 50%

- Temperatures typical of late summer in the Carolinas are
  expected.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
VFR to dominate thru daytime morning hrs. VCSH showers after
daybreak Mon, will increase in coverage as the onshore movement
of pcpn increases as the outer circulation of Isaias closes in
from the south. MVFR conditions should be intermittent at the
start of Mon aftn, becoming dominant with occasional IFR
conditions by early to mid Mon evening thru the end of the 24
hr Taf Issuance period.

Extended Outlook...Tropical Storm Isaias will produce Tropical
Storm conditions thru roughly 10Z Tue, given the latest
official track...with the center passing across the coast and
inland between Holden Beach and Myrtle Beach prior to sunrise
Tue. IFR/MVFR to dominate with a shot of LIFR across the coastal
terminals. Mainly VFR conditions from mid-day Tue morning and
beyond with much improved conditions. Mainly scattered afternoon
and evening showers and thunderstorms late week period.

&&

.MARINE...
Mostly moderate S winds at or below 15kts are expected today with
light SE wind waves at 4 seconds. Swell from Isaias between 8 and 10
seconds through Monday with waves ramping up Monday night into
Tuesday. Hazardous seas between 10 and 15 feet out to 20 NM and
upwards of 20 feet beyond 20 NM Monday night into Tuesday, with
marine conditions gradually improving Tuesday night into Wednesday.
Note that waterspout potential will also increase Monday as Isaias
nears.

Southwest flow over the waters continues through Fri with gradient
keeping speeds close to 10 kt. Seas will trend down through Fri,
dropping from 4 to 6 ft Tue night to 3 to 4 ft Wed and 2 to 3 ft Thu
and Fri. Southeast swell will continue to be dominant over a weaker
southerly wind wave.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...Hurricane Watch for SCZ054>056-058-059.
     Tropical Storm Warning for SCZ024-032-033-039-054>056-058-059.
     Flash Flood Watch from 8 AM EDT this morning through Tuesday
     afternoon for SCZ017-023-024-032-033-039-054>056-058-059.
     High Rip Current Risk through this evening for SCZ054-056.
     Storm Surge Warning for SCZ054-056.
NC...Hurricane Watch for NCZ105>110.
     Tropical Storm Warning for NCZ087-096-099-105>110.
     Flash Flood Watch from 8 AM EDT this morning through Tuesday
     afternoon for NCZ087-096-099-105>110.
     High Rip Current Risk through this evening for NCZ106-108-110.
     Storm Surge Warning for NCZ110.
     Storm Surge Watch for NCZ106-108.
MARINE...Hurricane Watch for AMZ250-252-254-256.
     Tropical Storm Warning for AMZ250-252-254-256.
&&

$$
SYNOPSIS...MCK
UPDATE...TRA
NEAR TERM...MCK
SHORT TERM...III
LONG TERM...III
AVIATION...DCH
MARINE...MCK


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