Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 290321

Area Forecast Discussion
National Weather Service Wilmington NC
1121 PM EDT Sun May 28 2017

Thunderstorms will finally exit east of the region around
midnight. Otherwise, high pressure centered offshore will extend
across the area through Monday. A cool front will approach and
enter the area from the northwest and stall across the area
during the early to mid week time line. Expect scattered showers
and thunderstorms along this front with a string of upper level
disturbances enhancing the convective activity.


As of 910 PM Sunday...SVR Watch 295 continues across the
forecast area through 1 AM Monday. The main severe threat is for
damaging wind gusts with hail a secondary threat. The
convective activity is moving from west to east at 25 to 35 mph.
Look for a decrease in the intensity of the storms after it
initially pushes thru the sea breeze. This observed with latest
reflectivity trends after the storm pushed across the sea breeze
in Brunswick County and into a sfc based stable marine layer.

However, with flow in the low levels westerly at 15 to 30 kt,
the sea breeze bndry will likely get pushed back to the coast
along with it`s marine layer weakening over land areas. As a
result, expect the latest convection to make it to the
immediate coast of both NC and SC with some weakening but should
still be able to produce atleast a strong+ wind gust.

Due to the relatively fast motion, flooding type rains are not
expected unless activity starts to train across the same
locations. Have peaked POPs at the likely category during this
evening and have the activity exiting east into the adjacent Atl
waters by midnight to 1 am edt.

As of 300 PM Sunday...A west to subtle southwest flow will
continue at the mid levels through the period. A very broad
front extends across the Mississippi Valley well to the west.
For our area there appears to be two decent chances of
convection, the first coming this afternoon and evening with
similar timing Monday.

Currently convective debris from last night`s convection is
exiting off the coast and a decent cumulus field is developing
in its wake matching up well with convective inhibition has
finally eroded from a 100mb Mixed Layer perspective. This trend
should continue and showers and thunderstorms should begin in
the next few hours. The GFS shows a smattering of convection
this afternoon with a little more enhancement/organization
around 00 UTC. The high resolution CAM guidance is showing a
similar scenario albeit with more of a delay in timing. I have
increased the pops slightly for the next six hours or so due
to these trends. If and moreso when things get going, severe
potential is fair game with strong winds and hail the primary
threats. For the overnight hours beyond 03 UTC, things should
be quiet persisting well into Monday morning.

For Monday afternoon, residual Piedmont troughing and very
similar thermal parameters will offer up more chances of
convection. Guidance pops from the MAV aren`t as high as this
afternoon and evening but may trend up in time which can be
the nature in the warm season regarding convection. SPC has
most of the area in a slight risk for Monday.

Thermal profiles show temperatures should be a little warmer
Monday afternoon as does the official forecast. Overnight lows
tonight will remain mostly in the 70s with maybe an upper 60 or
two well inland.


As of 300 PM Sunday...With a boundary stalled over the area
and some mid level energy still present Monday night may see a
continuation of the afternoons` convective activity. This is
especially suggesting by the 12Z WRF which shows a very
agressive, possibly feedback-contaminated convective signal over
mainly SC zones. Tuesday morning should offer a bit of a break
in radar activity though not necessarily a rain-free period.
With a little heating and the front still in the area Tuesday
afternoon should once again see at least scattered coverage of
thunderstorms. Coverage will wane to isolated or perhaps none at
all later Tuesday night.


As of 300 PM Sunday...GFS/ECMWF in agreement on the evolving H5
pattern in slowly migrating a broad but low amplitude trough
eastward across the Great lakes and Ohio valley then into
New England and SE Canada this period, while holding an upper
ridge of varying amplitude over Florida and the Bahamas. This
will allow a series of weak fronts and upper disturbances to
move to our coasts, offering daily chances of thunderstorms.
Late May/early June heating coupled with PWATS values between
1.50-1.80", and numerous surface boundaries, will support
convection much of the extended forecast period. Next weekend
potentially could turn wet, as enhancement of column moisture is
drawn from the Gulf of Mexico by low pressure over Texas on
Saturday, tracking to the Ohio Valley during Sunday. With the
abundance of clouds, daytime temperatures will run near normal
for the season, middle to upper 80s, but above average minimum
temperatures in the upper 60s to low 70s.


As of 01Z...The LBT and FLO terminals will likely see their
convection early this evening, with activity east of the the 2
terminals by 01Z-02Z. The pseudo LEWP is making eastward
progress and will affect the ILM-CRE-MYR terminals from 01Z-03Z.
Strong to possibly severe tstrm wind gusts to occur across the
coastal terminals. The inland terminals have seen their chance
earlier for possible severe wind gusts. Any convection that
affects them now may produce a strong wind gust. All terminals
will see a brief reduction of horizontal vsby from heavy rain to
1sm-3sm, and possibly lower from a direct hit from one of those
heavy rain producing shafts. Look for the main activity to
finally push off the Carolina Coasts and into the Atl Waters
between 03Z and 05Z.

Residual convective debris clouds will prevail during the
predawn Mon hrs and possibly up to a few hrs after daybreak Mon.
Otherwise, expect a repeat of today for Sun with WSW to WNW
5 to 10 kt winds except becoming SSW-SW 10 to 15 kt along the
immediate coast due to a pinned sea breeze. Convection will fire
up across the inland terminals during the mid to late aftn and
into the evening hrs and will indicate this with Prob groups.

Extended Outlook...MVFR/IFR conditions are possible in
thunderstorms Monday Night through Tuesday. More typical
summertime scattered showers and thunderstorms are possible
Wednesday and Thursday.


As of 830 PM Sunday...The majority of the convective activity
will diminish-some with regard to their intensity, after it
pushes thru the sea breeze and eventually off the NC and SC
coasts. The rather deep and stable sfc based marine layer will
act to squash the convection this time of the year. The
convection should push offshore during the early pre-dawn
Monday hours ie. between 1 and 3 am.

Overall synoptic pattern will produce a SW wind initially,
veering to the W during the predawn Mon hrs. Wind speeds
around 15 kt. Significant seas will run 2 to 4 ft and primarily
a function of 3 to 5 second period wind waves. No identifiable
ground swell to speak of.

As of 300 PM Sunday...Bermuda High pressure will keep a
southwest flow in place over the waters through the period.
Speeds will be mostly in a range of 10-15 knots with the
exception of a few hours this afternoon when stronger low level
jetting warrants a few hours of 15- 20. Speeds will relax a
little Monday. Significant seas will be 2-4 feet with the four
footers mostly confined to the next few hours coinciding with
the slightly stronger winds.

As of 300 PM Sunday...Cold front should be stalled over land,
keeping marine flow out of the SW. Solutions that push the front
farther and lead to veered flow currently not favored though
impossible to rule out. This boundary will tend to remain
quite stationary through the period keeping a fairly light
southwesterly flow across the waters. The proximity of the
boundary paired with the poorly defined nature of the Atlantic
high will keep wind waves minimal and preclude any swell energy
for an overall wave forecast of just 2 ft.

As of 300 PM Sunday...Near typical summer-like marine
conditions this period as SW winds prevail with 2-3 foot seas.
High pressure will remain centered just to the SE and E of
Bermuda, and weak troughing inland should maintain SW wind flow
Wed to Fri. The sea spectrum will be comprised of S-SSW waves
1-2 feet every 5 seconds and ESE waves 1-2 feet every 8 seconds.
TSTMS will be active this period, moving generally from land to
the coastal waters, and some may be strong from afternoon
heating. Getting a radar update before heading out may be in the
best interest of safely this period as we transition into a
more active lightning and TSTM wind gust season.


As of 930 PM Sunday...A coastal flood advisory has been issued
for low lying areas bordering the Lower Cape Fear River from
Wilmington southward. Latest tide guidance for the river gage
located in the lower Cape Fear River in the vicinity of downtown
Wilmington, has forecast levels reaching 5.85 ft MLLW at the
107 AM high tide early Monday Morning. Flooding along the lower
Cape Fear from Wilmington southward begins at the 5.5 ft MLLW.
Thresholds for shallow flooding will occur in a 3 hour window
centered around high tide and for this occurrence, it will run
from 1130 PM Sunday to 230 AM Monday.


NC...Coastal Flood Advisory until 3 AM EDT Monday for NCZ107.


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