Scientific Forecaster Discussion
fxus62 kilm 290543
Area forecast discussion
National Weather Service Wilmington NC
143 am EDT Mon may 29 2017
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.
Near term /through tonight/... all storms have exited offshore
and no further convection is expected overnight. Relevant
portion of previous discussion below:
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. Storm Prediction Center 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.
Short term /through Tuesday night/...
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.
Long term /Wednesday through Sunday/...
as of 300 PM Sunday...GFS/ECMWF in agreement on the evolving 500 mb
pattern in slowly migrating a broad but low amplitude trough
eastward across the Great Lakes and Ohio Valley then into
New England and southeast 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 precipitable waters 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.
Aviation /06z Monday through Friday/...
as of 06z...cluster of tstms beneath a mid-level impulse has
weakened and moved offshore, and VFR is expected through the valid
Trough moving offshore will cause a wind shift to the west/northwest this
morning, but speeds will remain light around 5 kts into daybreak.
Some mid and high level cloudiness will persist into the morning,
but ceilings are not expected. After daybreak, winds will slowly
back to the SW again as high pressure expands up the southeast coast. Winds
at the terminals Monday will be lighter than the past two days, but
a locally backed sea breeze with gusts of 15-20 kts is likely again
at cre/myr during the aftn. Scattered diurnal cumulus is also likely at
all terminals, but again, not cig and VFR will persist into the
evening. A mid-level impulse will approach from the west/SW late in the
valid period, likely accompanied by convection developing beneath it
and along a surface trough to the west of the area. Tstms are expected
to once again impact the terminals Monday night, and have introduced
-tsra to lbt/Flo, but most of the activity will hold off until
beyond this valid period.
Extended outlook...MVFR/IFR conditions are possible in
thunderstorms Monday night through Tuesday. More typical
summertime scattered showers and thunderstorms are possible
Wednesday through Friday.
near term /until 6 am Monday morning/...
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 west 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.
Short term /6 am Monday morning through Tuesday night/...
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.
Long term /Wednesday through Friday/...
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 southeast and east of
Bermuda, and weak troughing inland should maintain SW wind flow
Wed to Fri. The sea spectrum will be comprised of S-south-southwest waves
1-2 feet every 5 seconds and east-southeast waves 1-2 feet every 8 seconds.
Thunderstorms 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 thunderstorm 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 early this morning for