National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KCHS 081730
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
130 PM EDT Sat May 8 2021

.SYNOPSIS...
High pressure will prevail through the weekend. Low pressure
and a cold front will approach the region early week, then
linger through mid-week. High pressure will build into the
region by late week.

&&

.NEAR TERM /THROUGH TONIGHT/...
High pressure initially over Alabama, Georgia and the Florida
panhandle will drop southeast and split into two separate
regions this afternoon. One center will be found in the
northeast Gulf of Mexico, while the another high forms over the
nearby Atlantic. Meanwhile, a cold front will linger off to the
northwest.

With full sunshine, a west to northwest downslope flow in the
boundary layer and warm 850 mb temperatures, we expect a large
diurnal rise in temperatures. Our latest forecast shows max
temperatures in the upper 70s and lower 80s most communities
away from the coast. The resultant sea breeze will form during
the early afternoon, and hold shoreline locations down in the
lower and middle 70s.

Deep mixing and some enhancement to the pressure gradient will
lead to gusty afternoon winds, especially over locations east
of I-95 from the Savannah area north to Beaufort, Walterboro,
Charleston, Summerville and Moncks Corner. It won`t be anywhere
near as strong as the winds from yesterday, but still enough to
get westerly winds up near 20 mph at times prior to the sea
breeze backing winds around to the south and southwest.

Tonight: High pressure over the Atlantic will become the parent
high, as it tracks further into the ocean. Winds will decouple
in most places with sunset, and even though dew points will be
increasing as the synoptic flow becomes south-southwest,
conditions again favor good radiational cooling away from the
coast. It won`t be as cool as this morning was, but still
looking at min temperatures in the lower and middle 50s inland
from US-17, with 60-65F along the barrier islands, in the
Charleston metro and near the edges of Lake Moultrie.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY/...
Sunday: High pressure will shift further south as low pressure and
an associated cold front approach the region from the west. With a
tight pressure gradient, winds will be quite breezy. Though, another
rain-free day is expected. The area will be in the warm sector and
high temperatures will be in the mid to upper 80s inland and low 80s
just along the coast. Overnight Sunday, radiational cooling will be
less than ideal as cloud cover increases and winds remain somewhat
breezy. Low temperatures will be in the low to mid 60s inland with
upper 60s to low 70s along the coast.

Monday: A cold will sweep through the area on Monday before
departing offshore overnight. There are some inconsistencies within
the models of how much rain will actually occur across the area and
the timing. The best chances for rain remains over SE GA, though
could see a few showers across the SE SC as well. While the best
instability will be over the waters, there could be pockets of 700-
800 J/kg of SBCAPE. Therefore, have maintained mention of
thunderstorms. With sufficient shear, thunderstorms could become
organized and a few stronger storms will be possible. Another day of
80s is expected with lows in the 60s.

Tuesday: Another day of unsettled weather is possible as the cold
front sinks south before stalling across the waters and northern
Florida. Isentropic lift and PWATs around an inch and a half will
support scattered showers and thunderstorms. Otherwise, high
temperatures will be in mid to upper 70s across portions of SE SC
and low to mid 80s across SE GA. Lows will be in the mid to upper
50s inland and low 60s along the coast and in far SE GA.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
The weather will remain somewhat unsettled through late week as a
stationary front lingers in the vicinity, shortwave energy moves
through the area and high pressure prevails to the north. Showers
and thunderstorms will be possible on Wednesday and Thursday. While
at this time, the instability is quite limited, if the stationary
front lifts north, there could be a few stronger storms, mainly on
Thursday. High pressure should then build into the area on Friday.
Cooler temperatures are expected on Wednesday and Thursday, then a
warming trend will occur. Low temperatures will mostly be in the
50s.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
-- Changed Discussion --
18Z TAFs: VFR. Gusty W winds are expected at KCHS until sunset.

Extended Aviation Outlook: VFR to prevail with gusty winds during
the daylight hours Sunday and Monday. Thereafter, a cold front could
bring flight restrictions to both terminals due to low clouds and
showers/thunderstorms starting Monday afternoon.
-- End Changed Discussion --

&&

.MARINE...
Today through tonight: While a cold front will remain off to the
distant northwest, high pressure that originally is over the
Southeast will reform over the Atlantic this afternoon. That
high will expand tonight as its associated ridge axis sets up
from east to west across southern Georgia and northern Florida.

Winds will become S and SW with sea breeze influences this
afternoon. For the most part winds will be at or below 15 kt,
but some gusts will reach around 20-25 kt in Charleston Harbor
and on the Charleston County Atlantic waters late in the day
into the evening. However, the frequency and coverage of any 25
kt winds will be limited enough where we don`t anticipate a
Small Craft Advisory.

Seas of 2 to 3 ft will be common throughout tonight, except for
several hours of 4 foot seas reaching in the AMZ350 waters later
today and early tonight when winds will be their strongest.

Sunday through Thursday: As high pressure departs offshore and a
cold front approaches the region on Sunday, the pressure gradient
will tighten and winds will increase. Small Craft Advisories could
be needed for all waters, including the Charleston Harbor through
early Monday. Thereafter, winds will remain around 10-15 knots on
Tuesday and Wednesday. On Thursday, another round of Small Craft
Advisories could be needed for winds and seas. Showers and
thunderstorms will also be possible each day, with the exception of
a rain-free day expected on Sunday.

&&

.FIRE WEATHER...
-- Changed Discussion --
Relative humidity will fall to around 20 to 25 percent most places
this afternoon, prior to the passage of the sea breeze during the
early and mid afternoon. This occurs with mainly west winds that
reach around 15 or 20 mph, and highest near and east of I-95 from
Chatham County to Charleston and Berkeley County. As a result
of these conditions, we have a Fire Danger Statement until 7
PM. Once the sea breeze develops and spreads slowly inland,
relative humidity values will increase as winds become south or
southwest along and near the coast.

Locations outside of where we have the Fire Danger Statement
today will have similar relative humidity levels, but winds
will be quite a bit less.

For Sunday afternoon, relative humidity will fall to 25 to 30 percent,
while south and southwest wind gusts will reach 20 to 25 mph.
This will support the requirement for either another Fire
Danger Statement, or maybe even a Fire Weather Watch and/or a
Red Flag Warning, and would cover most if not all counties.
-- End Changed Discussion --

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.

&&

$$

NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...
MARINE...
FIRE WEATHER...