Area Forecast Discussion
Issued by NWS Charleston, SC
FXUS62 KCHS 290813
Area Forecast Discussion
National Weather Service Charleston SC
413 AM EDT Wed Mar 29 2017
A weak front will sag south over the area today, then move north as
a warm front Thursday night. A cold front will move through Friday
night followed by dry high pressure into Sunday. Unsettled weather
should return again next Monday, possibly lasting into Tuesday.
.NEAR TERM /THROUGH TONIGHT/...
Pre-dawn: Tranquil conditions will persist with mainly clear
skies and light/variable winds. There could be some patchy
ground fog in spots were some of the showers fell yesterday
in southeast SC, no significant vsby reductions are anticipated.
Today: Mid and upper level ridging will build across the GA and
the Carolinas, maintaining above average temperatures and
generally dry weather. Surface high pressure building to the
northwest and north, will push a weak cold front into the
forecast area. There is not much of a thermal gradient with the
front and it`s main impact will be subtle wind shifts this
morning over South Carolina. High temps will once again be in
the mid 80s many areas today, the beaches and barrier islands
should remain quite a bit cooler with onshore afternoon flow. We
have a slight chance of brief showers with the sea breeze
closer to the Altamaha River later this afternoon but too much
subsidence aloft to support any deeper convection.
Tonight: A bit of tricky forecast with a light onshore and
upslope flow. This synoptic pattern along with elevated surface
dew points favor some stratus development overnight and this
was supported by several 00Z model solutions. With low level
winds picking up a bit late, it looks a bit doubtful we will see
significant fog from build-down stratus, but there was enough
evidence to introduce some patchy fog around the Savannah River
Entrance south into coastal GA. Lows will be in the upper 50s
north to lower 60s south.
.SHORT TERM /THURSDAY THROUGH SATURDAY/...
A stalled front across southeast GA Thursday will shift north as a
warm front Thursday night followed by a cold front Friday night.
Rain chances will ramp up toward Thursday afternoon when deeper
moisture and isentropic ascent increase across the area. Thus,
showers and possibly a few thunderstorms (mainly across GA) are
expected Thursday afternoon/evening with a lull likely, especially
across GA, before increasing again toward daybreak Friday as
stronger synoptic forcing arrives. Precipitation should taper off
later Friday as the deepest moisture shifts northeast of the area.
Although wind fields will be strong Friday, instability appears
minimal and thus the threat for severe weather is low at this time.
Either way it should be a breezy day with gusts up to around 25-30
mph. Any lingering showers near the SC coast should end Friday
evening as a cold front moves through with dry conditions the rest
of the night into Saturday.
On Thursday temperatures will be a bit cooler than Wednesday behind
the front, especially across SC where it should stay below 80
degrees except close to the Savannah River. Temperatures Friday will
be moderated by the clouds/rain, likely only reaching close to 80
inland with a slight warmup Saturday as slight cool advection likely
gets overcome by some downslope warming.
.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
Dry high pressure to prevail through Sunday night although moisture
will be increasing toward Monday morning as low-level jetting ramps
up ahead of approaching low pressure from the west. Unsettled
weather is expected Monday into Tuesday although timing is a bit
uncertain at this point. Mid-level ridging should keep things dry
and quite warm Wednesday, possibly near record levels in GA.
Otherwise, temperatures should remain above normal through the
.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
VFR at KSAV and KCHS through 06Z Thursday. Small chances for
lower cigs developing/advecting off the Atlantic later tonight.
EXTENDED AVIATION OUTLOOK: Restrictions likely due to
showers/thunderstorms/low clouds, mainly Thu night into Fri. Breezy
conditions expected Fri.
Today: A weak cold front will drift into the waters today and
lose definition late as it mingles with the sea breeze
oscillations. Winds will gradually veer onshore and increase
close to 15 KT across Charleston Waters by early this evening
into tonight. GA waters will see light offshore winds early this
morning becoming onshore later today and tonight, speeds will
be closer to 10 KT. Seas will average 2-3 ft near shore with 3-4
FT offshore and some 5 footers out closer to the Gulf Stream.
Thursday through Monday: A warm front will shift north through the
area Thursday night/Friday. A cold front will then move through
Friday night/early Saturday. At some point prior to the cold frontal
passage sea fog could develop across the cooler near shore waters
and lead to low visibilities. Conditions will go downhill again
Monday as a storm system approaches from the west.
Expect a high chance for Advisories Thursday night across the outer
waters, expanding northward into the SC waters into Friday night as
strengthening winds build seas to 6-7 feet, highest toward the Gulf
Rip Currents: Moderate risk for rip currents along the SC coast
today. Winds becoming onshore and increasing late along with
long period 2-3 foot swells may produce rip currents. The
combination of higher than normal tides, onshore winds and
swells in the surf zone will support an enhanced risk for rip
currents, possibly lasting into Friday.
Strengthening onshore winds combined with swells impacting the coast
will cause saltwater inundation, especially in vulnerable coastal
areas. The high tides this evening and again on Thursday morning
could reach advisory levels, especially in SC. The Thursday
evening high tide could approach warning levels. Coastal Flood
headlines are expected with each of these tide cycles.