Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wilmington NC
214 PM EDT Friday Aug 29 2014
strengthening Bermuda high pressure over the western Atlantic will
bring warm late Summer weather conditions through the Labor Day
weekend...along with isolated afternoon thunderstorms. A weak
cold front approaching from the west will stall near the coast
next week...increasing local rain chances.
Near term /through tonight/...
as of 214 PM Friday...the front has moved to the northern edge of
the County Warning Area and the best moisture remains to the north
of the 925 mb Theta-E gradient and the latest blended total
precipitable water confirms the best moisture is along the
northern tier of counties for this afternoon. The 14 UTC hrrr
continues to show isolated thunderstorms north of a Lumberton to
Burgaw line so have added a 20 percent pop if the deeper moisture
does sneak farther south by the end of the day.
Calm winds are expected overnight and with high pressure to the
north...winds will shift to an onshore flow. This will increase
the low level moisture and it is expected to increase the
probability of fog and low stratus overnight. Lows overnight are
expected to fall to around 70.
Short term /Saturday through Sunday night/...
as of 214 PM Friday...a fair weather labor weekend on tap with
seasonable temperatures to accompany an overall dryish column
Saturday and Sunday. It appears there may be enough surface
heating and moisture return to pop a few showers or a storm
briefly along the corridor of low level convergence that will
strengthen along and near the sea breeze front in the afternoon to
early evening...with chances looking slightly better Sunday.
Light winds presently across the region are not advecting much
low-level moisture off the sea and mixing this afternoon has
allowed dewpoints to drop into the 60s over much of the area away
from the coast and coastal interior. Patches of fog may develop
over the interior cool pockets or protected coastal locations but
coverage should remain patchy versus widespread.
Maximums Sat/sun low/middle 90s west of I-95 and upper 80s to lower
90s farther east...minimums sun/Monday morning generally 70-76 and
mildest near the coast.
Long term /Monday through Friday/...
as of 214 PM Friday...middle to upper ridge will slip farther south
as more of a zonal flow developing as a very broad ridge takes
over the southern half of the Continental U.S. With a very broad trough
across the northern half. Bermuda high to the east will maintain a
warm and moist southerly return flow as Piedmont trough to the
west will remain Focal Point for convection through much of the
week. A shortwave will ride through the almost zonal flow on
Monday enhancing convection Monday afternoon and a westerly steering flow
will carry these showers/thunderstorms toward the coast. The pcp water
reaches up above 2 inches Monday night into Tuesday afternoon. A deeper drier
northwest flow will move in behind shortwave late Tuesday with pcp
water values dropping to 1.75 inches. Overall will see a warm and
humid air mass in place through much of the week with temperatures
running above normal and showers and thunderstorms enhanced by
some perturbations in the flow aloft...especially Monday into Tuesday.
Dewpoint temperatures up above 70 will keep overnight lows in 70s and
daytime highs will reach close to 90 along the coast and into the
middle 90s inland.
Aviation /18z Friday through Wednesday/...
as of 18z...expect VFR conditions through much of the forecast
period with west to southwest winds around 5 knots this am becoming
more southerly this afternoon and evening. Inland terminals may see
winds become S to south-southwest while coastal terminals become S to southeast.
Speeds should peak around 10 knots. With the S to southeast winds...an
increase in low level moisture is expected this afternoon into
tonight such that fog may develop overnight. For now...tafs have
MVFR fog and scattered clouds at 500 feet but there is the potential
for IFR fog after 06z. Burn off in the am will depend on the extent
of the fog but VFR is expected after 14z.
Extended outlook...a slight chance of showers with MVFR for our
northern terminals Sat afternoon. Increasing chances for precipitation
Sunday through Wednesday with MVFR conditions possible.
near term /through tonight/...
as of 214 PM Friday...currently seeing the sea-breeze circulation
on the near shore buoys and radar. The winds are expected to be
around 10 knots and from the southeast through the period. The
buoys are showing a 2 foot dominant wave this afternoon will as southeast
swell mixed in. With light winds expected in a weak pressure
gradient expect seas to remain around 2 feet until morning.
Short term /Saturday through Sunday night/...
as of 214 PM Friday...a good weekend on the waters weather-wise
as marine conditions remain quiet in an evolving and building
Bermuda high pressure pattern. Southeast winds around 10 knots Sat will
become S 10 to 15 knots Sunday...with weak surface trough forming
inland to sharpen the pressure gradient slightly. Seas 2 - 2.5 feet
expected over the weekend...in a mix of southeast waves 2 feet at 8-9
seconds and S waves 1 foot every 4 seconds. Any thunderstorms that develop
over the waters this weekend will remain isolated and favored late
night and through early morning.
Long term /Monday through Wednesday/...
as of 214 PM Friday...Bermuda high off shore and Piedmont trough
inland will maintain a persistent southerly return flow through
much of the week around 10 to 15 kts. The flow will be enhanced by
the sea breeze each afternoon. The weak southerly push will keep seas 1
to 3 feet with a slight chop each afternoon.