Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 221931
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
331 PM EDT Tue Jun 22 2021

.SYNOPSIS...
A cold front will approach from the west today along with a threat
of strong to isolated severe thunderstorms this afternoon and
evening. Cool and dry high pressure will build down from the
north Wednesday into Thursday with below normal temperatures.
Lingering front offshore pushes onshore as warm front on Friday
with increasing warmth and chances of showers or thunderstorms
into the weekend.

&&

.NEAR TERM /THROUGH WEDNESDAY NIGHT/...
Moisture rich environment ahead of approaching cold front this
afternoon, with pcp water values up over 2 inches, but lacking
in the sfc heating with such extensive cloud cover and shower
activity. The front was draped from SW to NE across the Raleigh
area around 3pm this aftn, evident by a line of convection. Overall,
expect best potential for stronger storm development associated
with lift along the front and enhanced by shortwave energy
rotating around main mid to upper trough into early this
evening. Increasing low level winds up to 45 kts with mainly
unidirectional shear out of the SW will help to create limited
potential for damaging wind gusts with the convection through
this evening. Convection will weaken and diminish as heating of
the day cuts off, tapering off once front moves through and
winds shift from SW to N-NE. SPC keeps our local area in
marginal risk of severe weather through this evening with a few
strong to severe storms possible, with main threat of damaging
wind gusts.

Cold front will drop into the area between 10p and midnight,
clearing the coast by daybreak. Lingering moisture and clouds
should move off the coast through Wed morning as sfc high builds
down from the north, but mid to upper trough will flatten out
and lift north leaving front lingering in the offshore waters as
high pressure builds down from the north. Winds will shift
around from SW to NE as front moves through. Soundings and
moisture profiles show deep drying through the column with some
lingering low level moisture which dries out by Wed aftn, drying
out further into Wed night. Pcp water values drop from 1.6
inches before daybreak Wed down less than an inch by midnight
and possibly down to a half inch by Thurs morning.

Overall, expect clearing skies and increasing sunshine through
Wed with relatively cool and dry air keeping temps near 80, over
5 to 10 degrees below normal. Overnight lows will be closer to
normal tonight, but by Thurs morning, lows will drop down near
60 inland. Should see some fog around inland but as dewpoints
drop, any fog should clear into the morning. Dewpoint temps
close to 70 this evening will be down in the 50s by Wed night.

&&

.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
A weakening wedge of surface high pressure will be in place through
the period. Models have trended much drier with the forecast, now
suppressing the measurable rain offshore, a trend we were starting
yesterday. Clouds may linger along the coast however while inland
locales see breaks of sunshine. This will likely suppress highs by a
few degrees below their inland counterparts; both inland and coastal
locations remaining below climatology.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Weak flow aloft on Friday while a weak warm front/trough moves
ashore. Morning showers along the coast will spread inland along
with the boundary. With highs still only in the lower 80s
instability may be meager enough for only isolated thunder. Fairly
deep but weak onshore flow becomes established Saturday which should
wind up fairly seasonable and with just a slightly elevated coverage
of mainly diurnal storms. The deep onshore flow remains Sunday but
subtle height rises from the northeast should tend to trim
convective coverage back to normal (30 percent-ish). The upper level
ridge to our northeast strengthens further Monday into Tuesday. The
deep layer onshore flow will thus continue and keep the area
susceptible to diurnal showers and isolated thunderstorms as the
deep layer of marine air contains only very weak lapse rates.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
Weak convection already occurring over portions of the CWA. A
cold front will approach the region from the west this
afternoon. Another round of stronger convection is expected from
mid afternoon into the evening. Brief periods of IFR
visibilities are expected. Winds shift to the north overnight,
post frontal with some IFR ceilings. Gusty northeast winds and
cooler on Wednesday.

Extended Outlook...Predominately VFR Wednesday through early
Friday. Unsettled weather over the weekend with a good chance of
rain.

&&

.MARINE...
Through Wednesday night...
SCA conditions will continue into tonight in gusty SW winds
ahead of a cold front. SW wind speeds are 25 to 30 kt
sustained. Expect the CFP to occur during the pre-dawn Wed hrs,
sinking SE- ward to just offshore before stalling during Wed.
Winds will back to the NE-ENE after FROPA and actually may be
underdone by guidance. The post cold frontal NE surge will lie
just below SCA thresholds but the seas will be slow to subside
due to the stalled front in close proximity and the continued
pseudo/fresh swell feed. SCA thresholds will be borderline
during Wed, especially the waters off Cape Fear. Seas generally
5 to 8 ft at the start, subsiding to 3 to 5 ft at the end of the
fcst period but subject to change especially toward the end.
Potential SMW type convection by midday today and continuing
into the evening with potential for 34+ kt wind gusts and
occasional/frequent reduced vsby below 1nm at times from the
heavy rain.

Thursday through Sunday...E to NE winds Thursday as high pressure
wedging in from the north starts to weaken/break down. Flow turns
more southerly on Friday as the continuation of this process allows
a warm front to move ashore. Over the weekend the gradient remains
weaker than normal as Atlantic high pressure is displaced north and
east of its more normal June position closer to Bermuda. The short
period wind wave will dominate seas through the period but there
will be a few longer period wave components, primarily out of the
southeast. One will have a 7-8 second period and the other 12-13
seconds.

&&

.TIDES/COASTAL FLOODING...
Abnormally low tides, below -1 ft MLLW, will continue for the
next several tide cycles as we approach the full moon on
Thursday.


&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...High Rip Current Risk until 8 PM EDT this evening for SCZ054.
     Beach Hazards Statement until 8 PM EDT this evening for SCZ056.
NC...High Rip Current Risk until 8 PM EDT this evening for NCZ106-
     108-110.
MARINE...Small Craft Advisory until 1 AM EDT Wednesday for AMZ250-252-
     254-256.

&&

$$
SYNOPSIS...ILM
NEAR TERM...RGZ
SHORT TERM...MBB
LONG TERM...MBB
AVIATION...43
MARINE...MBB/RGZ
TIDES/COASTAL FLOODING...RGZ


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