Special Marine Warning 32, NWS Wilmington, NC

Area Forecast Discussion
National Weather Service Wilmington NC
749 PM EDT Thu Jun 3 2021

.SYNOPSIS...
Showers and thunderstorms will continue into the first part of
the weekend, but will diminish as deep moisture shifts eastward
Saturday into Sunday. A warming trend with increasing sunshine
through early next week, will bring temperatures a few degrees
above normal for early June.

&&

.UPDATE...
A lull in precipitation appears likely from SW to NE across the
area, but not without rotation noted in a few strong showers
and isolated TSTMs, and a tornado warning was issued for a
persistent couplet over NE Marion county.

The focus will turn to the waters as nocturnal convection
expands south of Cape Fear, and is directed onshore, implying
the coastal areas may see periods of heavy rain from around 4am
to 10am, where several inches of rainfall is easily attainable.
A flash flood watch will need to be further looked into from
Brunswick county northward along the north coast because of the
potential for training downpours early Friday.

&&

.NEAR TERM /THROUGH FRIDAY NIGHT/...
Overall setup is one that lends itself to an abundance of rainfall,
but also one that creates a great deal of difficulty nailing down
when and where rain will fall. Air mass will remain juicy through
Fri before drier air starts building in. Precipitable water between
1.75 and 2 inches through Fri falls closer to 1.3 inches Fri night.
The drop in PWAT coincides with the arrival of the mid-level trough
axis and the shift from deep southwest flow to more westerly flow
aloft. Bermuda High will continue to pump in low level moisture Fri
night which may lead to showers lingering along the coast into Sat
morning. The 5h trough also pushes a boundary into the region, but
hesitate to call it a cold front. The boundary ends up stalling in
the area Fri night, laying parallel to the flow aloft, further
enhancing potential for rainfall along the coast. High probability
that most of the area ends up with substantial rainfall through the
next 36 hours with amounts in excess of 3 inches possible in some
areas.

Severe threat will persist into the evening before surface based
instability starts to weaken, allowing the threat to slowly
diminish. Damaging wind will be the main concern, with potential for
a wet microburst given forecast soundings. A tornado is also a
possibility, especially given the number of lingering convective
boundaries and shear in excess of 30kt later today into this
evening. Not too worried around any widespread or life threatening
flooding at this point. Widespread drought conditions and low
stream/river levels should minimize the risk of flooding, even with
the expectation that many storms will have high rainfall efficiency.
May see issuance of a few statements for localized minor flooding,
especially if storms persist over 1 area, but this will be the
exception not the rule. Similar story concerning severe threat on
Fri, although the timing would be confined more to late morning
through mid afternoon.

Overnight lows, both tonight and Fri night, will end up 5 to 8
degrees above climo. Cloud cover and southerly flow will contribute
to the warmer temperatures. Highs Fri will end up around climo, with
potential for above climo temperatures in areas where the sun
happens to break through cloud cover for an extended period of time.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
Deep feed of tropical moisture will shift off to the east late Sat
into Sun as mid to upper trough moves east and ridge builds in for
Sunday. Bermuda high remains in place at the sfc with southerly
return flow maintaining a warm and humid air mass with temps
near normal on Saturday but warming well into the 80s to around
90 with increasing sunshine and H5 height rises into early next
week. overnight lows will be in the 60s.

Soundings and moisture profiles show drying through the mid
levels from west through late Sat into Sat night. the NAM is
showing last of mid to upper level energy riding across the area
late aftn on Sat, with ridging, subsidence and dry air aloft by
Sun. The best chc of shwrs and tstms will be south and east of
the area on Sun, but localized shwrs can not be ruled out with
residual moisture across the area, especially in SC.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
Closed low over Texas will help amplify the ridge over the
Southeast into Mon before it begins to lift north into midweek.
A deeper tropical feed of moisture will remain west of the area
and do not expect anything more than localized convection Mon,
but model solutions differ into midweek and looks like
convection could become a bit more widespread, but overall a
typical summertime pattern continues with Bermuda High in
control. Warm and humid weather will continue with light
southerly winds and temps well into the 80s to near 90 inland
and overnight lows in the upper 60s most places.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
Difficult flight conditions due to MVFR and occasional IFR
restrictions in mist, rain, and low clouds. This will be
especially true at coastal terminals from 8z-14z when periods of
heavy rain will move north along the NE SC and SE NC coast,
reducing VSBY in rain. Locally gusty winds to 35 kt should be
expected near the coast early Friday, as convection moves
onshore.

Extended Outlook...Flight category restrictions are possible in
scattered showers and thunderstorms through the weekend, as high
pressure offshore maintains moist southerly flow across the
area.

&&

.MARINE...
Through Friday night...Bermuda High remains in control through
Fri night with a slight southeast shift later Fri and Fri night.
Southerly winds will remain a fixture through Fri night with
speeds ranging from 10 to 15 kt overnight to 15 to 20 kt from
midday into the evening. Seas 3 to 4 ft into the evening will
build to 4 to 5 ft, mainly a combined southerly swell/wind wave,
before dropping to 3 to 5 ft Fri and Fri night. Currently no
headlines are planned through Fri night.

Saturday through Tuesday...A pattern fairly typical of summer
will remain in place with southerly flow around Bermuda High.
Winds should less than 15kts with a slight increase near shore
each aftn in sea breeze. Seas up to 3 to 4 ft through Sat night
will diminish a bit to 2 to 3 ft as ridge builds aloft. A SE
swell up around 8 seconds will dominate.

&&

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

&&

SYNOPSIS...ILM
UPDATE...MJC
NEAR TERM...III
SHORT TERM...RGZ
LONG TERM...RGZ
AVIATION...MJC
MARINE...III/RGZ