Area Forecast Discussion
Issued by NWS Charleston, SC

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FXUS62 KCHS 290754
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
354 AM EDT FRI AUG 29 2014

.SYNOPSIS...
ATLANTIC HIGH PRESSURE WILL EXPAND WESTWARD THROUGH THE WEEKEND AND
PERSIST INTO THE MIDDLE OF NEXT WEEK. AN INLAND TROUGH OF LOW PRESSURE
MAY DEVELOP IN THE MID WEEK TIME PERIOD.

&&

.NEAR TERM /THROUGH TONIGHT/...
PRE-DAWN...UPPER RIDGING DOMINATING SE GEORGIA AND SOUTHERN SOUTH
CAROLINA EARLY THIS MORNING. MAINLY CLEAR SKIES AROUND FOR DAYBREAK
WITH PATCHY FOG IN A FEW AREAS THANKS TO SOME INCREASED LOW LEVEL
MOISTURE OVER THE REGION AND LINGERING DRIER AIR IN THE BOUNDARY
LAYER. AT THIS TIME...NOT EXPECTING ANY SIGNIFICANT VSBY PROBLEMS
AS THE FOG SHOULD REMAIN SHALLOW IN NATURE. TEMPS RUNNING A BIT
WARMER THIS MORNING WITH A FEW COOLER RURAL INLAND SPOTS PERHAPS
DIPPING TO THE LOWER 60S FOR MINS.

DEEP LAYERED RIDGING WILL HOLD FIRM THROUGH TONIGHT WITH DRY WEATHER
PREVAILING. THE ONLY FEATURE OF NOTE THIS MORNING IS A POCKET OF
ENHANCED MOISTURE BELOW 800 MB OFF THE COAST...THE 00Z MODELS
INITIALIZED THIS FEATURE WELL...BUT THE ONLY CONSEQUENCE FROM
WEAK MOISTURE ADVECTION ALONG THE SOUTH CAROLINA COAST WILL LIKELY
BE A BIT MORE IN THE WAY OF AFTERNOON CUMULUS/STRATOCU AS HINTED
BY FORECAST CLOUD COVER PROGS FROM THE NAM/GEM. WE CANNOT TOTALLY
RULE OUT A BRIEF SHOWER ALONG THE SEA BREEZE BUT POPS MAINLY BELOW
10 PERCENT GIVEN THE WEALTH OF DRY AIR ALOFT AND GENERAL SUBSIDENCE.

TONIGHT...QUIET WEATHER LINGERS WITH MAINLY CLEAR SKIES AND LIGHT
TO CALM WINDS. THE POSSIBILITY OF PATCHY LATE NIGHT FOG EXISTS
ONCE AGAIN. WHILE THE MENTION MAY EVENTUALLY WORK IT/S WAY INTO
OUR FORECAST PRODUCTS LATER TODAY...CONFIDENCE IN EXTENT AND LOCATION
WAS NOT HIGH ENOUGH FOR INCLUSIONS JUST YET.

&&

.SHORT TERM /SATURDAY THROUGH MONDAY/...
SATURDAY AND SATURDAY NIGHT...ALOFT THE REGION WILL BE SOLIDLY UNDER
THE CENTER OF AN EXPANSIVE MID/UPPER LEVEL RIDGE AND ASSOCIATED
ANTICYCLONE. MEANWHILE AT THE SURFACE...AN AREA OF HIGH PRESSURE
WILL START THE DAY POSITIONED TO THE NORTHEAST BEFORE IT MOVES
EASTWARD OVER THE NORTH ATLANTIC. THIS WILL PLACE THE REGION UNDER
THE WESTERN PERIPHERY OF THE HIGH COVERING MUCH OF THE ATLANTIC FOR
THE FIRST OF THE WEEKEND. PWATS ACROSS MUCH OF THE FORECAST AREA
APPEAR QUITE DRY...GENERALLY LESS THAN 1.5 INCHES. THIS LACK OF
MOISTURE...COMBINED WITH THE RIDGE ALOFT AND A SUBSTANTIAL
SUBSIDENCE INVERSION NOTED IN THE 700-800 MB LAYER WILL KEEP THE
BULK OF THE AREA DRY. THERE IS SOME DEEPER MOISTURE PROGGED ACROSS
SOUTH AND CENTRAL GEORGIA...SO THE FORECAST CONTAINS A SMALL SLIVER
OF SLIGHT CHANCE POPS ALONG THE ALTAMAHA. HIGHS WILL RUN IN THE LOW
TO MID 90S AWAY FROM THE IMMEDIATE COAST...WITH LOWS IN THE LOW/MID
70S. THESE TEMPERATURES ON AVERAGE WOULD BE ABOUT 2-4 DEGREES ABOVE
CLIMATOLOGY FOR LATE AUGUST.

SUNDAY THROUGH MONDAY...THE OVERALL PATTERN WILL REMAIN UNCHANGED
THOUGH THE RIDGE ALOFT WILL MORPH A BIT AS IT BECOMES A BIT MORE
NARROW AND MORE WEST/EAST ORIENTED WITH TIME. THE FORECAST AREA WILL
ALSO REMAIN UNDER THE INFLUENCE OF THE WESTERN PERIPHERY OF ATLANTIC
HIGH PRESSURE. PRECIPITATION CHANCES WILL PRIMARILY BE DRIVEN BY
CONVERGENCE ALONG THE AFTERNOON SEABREEZE AND MESOSCALE BOUNDARY
INTERACTIONS. MODEL SOUNDINGS STILL LOOK QUITE UNIMPRESSIVE WITH A
CAPPING INVERSION PRESENT EACH AFTERNOON. WITH SUCH A LARGE RIDGE
ALOFT AND THE PRESENCE OF THE CAP...I HAVE DECIDED TO KEEP POPS IN
THE 20-30 PERCENT RANGE EACH AFTERNOON. TEMPERATURES WILL QUITE
SIMILAR TO SATURDAY...WITH HIGHS IN THE LOW/MID 90S AND LOWS IN THE
MID 70S.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
THROUGH THE LONG TERM PERIOD...THE LARGE UPPER RIDGE WILL CONTINUE
TO INFLUENCE THE AREA. THE RIDGE WILL UNDERGO A TRANSITION IN THE
MID/LATE WEEK TIME PERIOD AS IT RETROGRADES BACK TO THE WEST ACROSS
THE LOWER MISSISSIPPI VALLY IN RESPONSE TO A TROUGH MOVING ACROSS
CENTRAL AND EASTERN CANADA. THE PATTERN IN THE LOW LEVELS WILL STILL
FEATURE THE INFLUENCE OF THE ATLANTIC HIGH...THOUGH THERE ARE
INDICATIONS THAT AN INLAND TROUGH OF LOW PRESSURE WILL DEVELOP IN
THE TUESDAY/WEDNESDAY TIME FRAME. AS THIS OCCURS...THE COVERAGE OF
AFTERNOON/EVENING SHOWERS AND THUNDERSTORMS MAY TICK UPWARD A BIT.
THE FORECAST FEATURES SLIGHT CHANCE TO CHANCE POPS EACH AFTERNOON
AND EVENING. TEMPERATURES WILL REMAIN ABOVE NORMAL WITH THE RIDGE
ALOFT.

&&

.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
VFR THROUGH 06Z SATURDAY. THE PROBABILITY FOR PATCHY GROUND FOG WILL
INCREASE LATE TONIGHT/AROUND DAYBREAK THIS MORNING...BUT THE CHANCE
FOR FLIGHT RESTRICTIONS REMAINS TOO LOW TO INCLUDE WITHIN 06Z
TAFS.

EXTENDED AVIATION OUTLOOK...VFR CONDITIONS WILL PREVAIL. VERY LOW CHANCES
OF DIRECT HITS FROM ISOLATED SHOWERS/THUNDERSTORMS THIS WEEKEND THROUGH
EARLY NEXT WEEK. ALSO LOW CHANCES FOR EARLY MORNING FOG THROUGH EARLY
NEXT WEEK.

&&

.MARINE...
THROUGH TONIGHT WITH HIGH PRES IN CONTROL AND WEAK GRADIENTS...
LIGHT WINDS MOSTLY 10 KT OR LESS. SEAS GENERALLY 2 TO 3 FT TODAY
AND TONIGHT...MAINLY IN SWELL.

SATURDAY THROUGH TUESDAY...OVERALL CONDITIONS WILL BE VERY QUIET AS
THE PATTERN IS DOMINATED BY ATLANTIC HIGH PRESSURE. WINDS WILL
GENERALLY BE SOUTHERLY AND 15 KT OR LESS...STRONGEST ALONG THE
LAND/SEA INTERFACE WITH THE AFTERNOON SEA BREEZE. AS A RESULT...SEAS
WILL BE 1-2 FT WITHIN 20 NM AND 2-3 FT BEYOND.

&&

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

&&

$$

NEAR TERM...
SHORT TERM...BSH
LONG TERM...BSH
AVIATION...
MARINE...BSH





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