Area Forecast Discussion
Issued by NWS Wilmington, NC
FXUS62 KILM 301922
Area Forecast Discussion
National Weather Service Wilmington NC
322 PM EDT Thu Mar 30 2017
Showers and storms will move in from the west and southwest
late this afternoon and evening, and again overnight into
Friday. A few storms could be strong to severe. A cold front
will follow late Friday, with a drying trend into the weekend
as high pressure takes hold. Low pressure early next week will
bring more showers and thunderstorms. Brief high pressure may
be followed by another round of showers and thunderstorms next
Thursday and Thursday night.
.NEAR TERM /THROUGH FRIDAY/...
As of 3 PM Thursday...Storms over central SC will continue to
advance NNE and may impact Darlington and Marlboro counties in the
late afternoon to early evening. Loss of heating is expected to de-
intensify the storms after 7pm-8pm, but there is a 2-3 hour window
where strong wind gusts may be experienced mainly west of I-95
before the storms weaken. After 2am, increasing convergence offshore
associated with a warm front will spawn convection that will be
directed northward into the Cape Fear region. A axis of elevated
precipitable waters along the warm front of around 1.5" will support
occasional downpours. 1 km helicity fields suggest a few cells may
undergo weak rotation as they move onshore. A low-level jet of
around 35 kt could help to produce gusty surface winds brought down
by the convection. After 7am-8am, a squall or broken line of TSTMS
will be moving east and approaching I-95, associated with the main
short-wave impulse. Bulk shear parameters will support potentially
40-50 kt wind gusts embedded in this line, which looks timed to
clear the coast by midday/early afternoon. Despite this, showers and
a few storms may linger through afternoon, beneath a cold pool and
in particular if the sun pop out and low-level warming aids in
booting column instability, and small hail cannot be ruled out
behind the main squall earlier in the day. No cold advection and a
mild day is on tap for Friday. The SPC maintains a marginal risk of
severe weather Friday morning.
.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 3 PM Thursday...Brief period of weak cold advection sets up
Fri night as shortwave passes north of the area and cold front moves
offshore. Cold advection has a small affect on Fri night lows,
dropping most ares into the mid 50s by Sat morning. However this is
still some 10 degrees above climo. Deep westerly flow aloft Fri
night transitions to northwest Sat and Sat night as the 5h trough
exits and shortwave ridge starts to build over the southeast.
Combination of mid level ridging and modified continental high will
keep temperatures mild Sat and Sat night. Highs Sat will be in the
mid to upper 70s with a few 80s across inland areas. Lows Sat night
are affected by some radiational cooling due to surface ridge axis
moving into the region late. Lows still end up above climo, but only
by a few degrees. Ridging will also keep skies mostly cloud free
through period with no chance of rain.
.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 3 PM Thursday...Seasonable to slightly mild on Sunday as
mid level ridge remains overhead, though moving eastward. Also
progressing eastward will be a potent southern branch shortwave.
This feature will lead to increasing cloud cover and rain
chances later Monday. Though weakening in depth slightly it does
maintain a neutral tilt and would not be surprised to see small
severe weather chances called for in future SPC outlooks. Any
lingering wet weather Tuesday morning should quickly shift off
the coast by midday or early afternoon though naturally a day 5
forecast is often subject to timing tweaks. Wednesday finds mid
level ridging over the area again but the pattern remains quite
amplified and progressive. Broad, high amplitude troughiness
should push a cold front into the area on Thursday bringing
another chance for possibly significant showers and
thunderstorms. Some models indicate that we may be in for quite
a cooldown following this frontal passage.
.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
As of 1715Z...Scattered to broken cumulus, and stratocumulus,
with ceilings occasionally dropping to MVFR. Late tonight
into Friday, ceilings to lower with showers and thunderstorms
increasing from SW to NE with the coastal terminals the last to
experience widespread shower and thunderstorm activity AFT 9Z,
AFT 5Z inland terminals. Expect ceilings and visibilities to
drop to MVFR and IFR in rain and TSTMS. Some TSTMS may produce
surface wind gusts as high as 45 KT.
Extended outlook...MVFR to IFR conditions likely persisting
into at least the first part of Fri. More showers and
thunderstorms developing Mon and through Mon night will have
the potential to produce flight restrictions.
NEAR TERM /THROUGH FRIDAY NIGHT/...
As of 3 PM Thursday...A small craft advisory is posted for
tonight through most of Friday as a strong low pressure system
moves from the central Appalachians eastward across Virginia. Se
winds tonight will increase to 20-25 KT, veering to S and SW
tonight into Friday. Seas generally 5-7 feet late tonight and
much of Friday. TSTMS will impact the waters from S to N in the
pre-dawn hours to a few hours after daybreak Friday, and then a
squall line will track from west to east across the waters
around midday into early afternoon. Some of the storms may be
strong to severe, with locally higher winds and waves in and
near the TSTMS. Dominant periods of 9-10 seconds early this
eveinig will shorten to 6-7 seconds making waves steeper. Slow
improvement can be expected late Friday into Saturday as winds
go NW to W and ease.
SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 3 PM Thursday...Cold front will be moving across the
waters as the period begins. Strong southwest flow ahead of the
front will become west and then northwest Fri night into
Saturday. Gradient will slowly weaken following the passage of
the front and speeds should drop from 20 to 25 kt ahead of the
front to a solid 15 kt by daybreak Sat. Little if any cold
advection following the front will keep winds in the 10 to 15 kt
range Sat. Cool surge moves down the coast Sat night with north
to northeast winds increasing to a solid 15 kt as the period
ends. Seas running 4 to 8 ft at the start of the period will
diminish overnight as wind speeds drop and flow becomes
offshore. Seas will be under 6 ft by Sat morning and 2 to 4 ft
by midday. Seas continue dropping into Sat evening before
slightly increasing late Sat night as cool surge arrives.
LONG TERM /SUNDAY THROUGH TUESDAY/...
As of 3 PM Thursday...Northeast winds Sunday will veer as high
pressure centered to our north progresses east. The high will
not be particularly strong nor bookended by significant fronts
and this will keep the wind speeds down. With light winds and in
the absence of much swell energy seas will be rather
diminutive. Additional veering to SE or even S on Monday as a
healthy system approaches from the west. The strength of teh
upper wave will allow a surface low to move east across the gulf
states. High pressure trying to hold on well off the coast will
ramp up the gradient to where advisory appears likely. The post
frontal veer to a more offshore flow will try to push some of
the larger waves further out to sea but it appears to occur
gradually, as does the abatement of wind speeds. Flags may still
be needed Tuesday.
MARINE...Small Craft Advisory from 11 PM this evening to 2 AM EDT
Saturday for AMZ250-252-254-256.