Scientific Forecaster Discussion
fxus62 kilm 171901
Area forecast discussion
National Weather Service Wilmington NC
301 PM EDT Thu Aug 17 2017
high heat and humidity will continue across the area into Friday.
Showers and thunderstorms will increase in coverage over the
weekend ahead of a weak cold front, which will likely stall near
the area. Another cold front will push through the area next
week, with unsettled weather expected to continue.
Near term /through Friday/...
as of 300 PM Thursday...latest radar imagery is showing quite the
coverage of convection across the area this afternoon, much more
widespread than was seen yesterday. Returns are showing plenty of
lingering boundaries, which along with the weak Piedmont trough and
seabreeze, have been aiding in the development thus far today.
Slower storm motion and precipitable water values over 2 inches will continue to
support localized heavy rainfall, and the potential for minor
flooding. Expect convection to dissipate into the overnight
hours, with low temperatures dipping into the mid 70's. Do not
anticipate much in the way of fog develop or low cigs as
lingering mid to high level clouds are expected into the morning
On Friday, weak riding aloft will set up across the area ahead of an
approaching weak cold front which is expected to affect the
area this weekend. With high temperatures in the lower 90's and
dewpoints in the mid to upper 70's, anticipate heat indices in
the 100's once again. At this time, do not expect all areas to
reach heat advisory criteria, but it more than likely will be
warranted for portions of the area. Will mention the potential
for typical summertime isolated to scattered convection in the
afternoon hours with diurnal heating, lingering boundaries and
available low level moisture.
Short term /Friday night through Saturday night/...
as of 300 PM Thursday...longwave trough digging across the Ohio Valley
will drop southeast into Saturday night, pushing a surface cold front into
the area. Ahead of this feature, deep SW flow advects tremendous
moisture in the form of pwats over 2.25 inches Saturday, which
should serve as fuel for convection along the front, especially
Saturday aftn/eve where it merges with the sea breeze. This is in
response to continued very warm and unstable air, with MLCAPE over
2000 j/kg likely as highs rise into the low 90s and dewpoints remain
at least the mid 70s, if not near 80 in some places. Most of this
convection should wane with loss of heating, but should refocus
offshore as the front stalls in the vicinity. Temps Saturday night
will be cooler than we have seen in many days as some dry advection
works into the column, pushing mins into the mid 70s, down from near
80 Friday night.
Long term /Sunday through Wednesday/...
as of 300 PM Thursday...stalled front really losing its identity to
our west on Sunday while light zonal mid level flow helps to confine
deepest moisture and thus best rain chances along the coast. This
front appears to wash out completely by Monday leaving behind some
weak troughiness on Monday. This doesn't elucidate much regarding
eclipse view especially along the coast since in such a
setup cumulus development should be fairly widespread and vertically
vigorous. Tuesday should represent the lowest rainfall chances
during the period with a pinned seabreeze, zonal flow aloft, and a
Piedmont trough to our west. Energetic northwest flow and the next
cold front arrive on Wednesday. This front may have a better chance
than the early week boundary in clearing the area at least in part
on Thursday as there is a stronger upper trough and higher surface
pressures driving its progress.
Aviation /19z Thursday through Tuesday/...
as of 18z...potential for periods of MVFR in any heavy
downpours and stronger storms this afternoon and evening.
Otherwise expect VFR.
Latest radar imagery depicts scattered showers and thunderstorms
across the area this afternoon, as heavy downpours are already
creating reduced visibilities at kilm. Expect trend to continue
throughout the rest of today as thunderstorms in the vicinity prevails in going
forecast, with tempo groups to account for scattered convection.
Into tonight, expect convection to dissipate, giving way to VFR
through into Friday morning, with passing mid level clouds.
Winds overnight will be light and variable.
Extended outlook...potential for MVFR/IFR through Friday as
unsettled weather continues, with chances increasing into the
weekend with a passing cold front. Would not entirely rule out
patchy stratus/fog towards the morning hours each day.
near term /through tonight/...
as of 300 PM Thursday...southwest winds around 10 kts this
evening into the overnight hours will increase to 10 to 15 kts
Friday afternoon ahead of an approaching weak cold front. Seas
of 2 ft are expected through the period, with 3 fters gradually
building in across the outer waters.
Short term /Friday through Saturday night/...
as of 300 PM Thursday...cold front approaching from the northwest will
stall just inland from the coast Saturday. This leaves SW flow
across the waters, with wind speeds around 15 kts through the
period. These winds will help drive a 3-4 ft/5sec SW wind wave atop
the persistent 8-9 sec southeast swell, and seas will be 2-4 ft across all
Long term /Sunday through Tuesday/...
as of 300 PM Thursday...very light southwesterly flow Sunday
and Monday with a cold front decaying into a weak surface
trough. Seas will be running their fairly 'normal' 2-3 and
occasionally 4 ft. The trough may wash out for a time Monday
night for some light and variable winds but it reforms Tuesday
for a return of south to southwesterly flow, likely capped at
SC...heat advisory until 5 PM EDT this afternoon for scz017-023-024-
NC...heat advisory until 5 PM EDT this afternoon for ncz087-096-099-