Area Forecast Discussion
Issued by NWS Charleston, SC

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000
FXUS62 KCHS 300750
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
350 AM EDT SAT AUG 30 2014

.SYNOPSIS...
ATLANTIC HIGH PRESSURE WILL EXPAND WESTWARD THROUGH THE WEEKEND AND
PREVAIL THROUGH AT LEAST THE MIDDLE OF NEXT WEEK. A COLD FRONT COULD
APPROACH THE REGION LATE NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
PRE-DAWN...MAINLY CLEAR SKIES MAY GIVE WAY TO SOME PATCHES OF STRATUS
AND FOG ACROSS PORTIONS OF THE INLAND FORECAST AREA NEARING DAYBREAK.
WEAK LOW LEVEL ONSHORE FLUX MAY BEGIN TO GENERATE SOME MORE IN THE
WAY OF DAYBREAK CUMULUS ALONG THE BEACHES AND BARRIER ISLANDS.

WHILE THE EXPANSIVE DEEP LAYERED RIDGE HOLDS FIRM TODAY AND TONIGHT
THE ATTENTION TURNS TO THERMODYNAMICS AND THE MESOSCALE TO GENERATE
MAINLY SHALLOW SEA BREEZE AND BOUNDARY DRIVEN SHOWERS AND PERHAPS
A FEW TSTMS THIS AFTERNOON. DEEPER MOISTURE AND BETTER INSTABILITY
IS POSITIONED FROM SW GEORGIA TO NE FLORIDA AND MAINLY S OF THE
ALTAMAHA RIVER REGION...CONVECTIVE CONVERAGE ACROSS OUR REGION IS
EXPECTED TO REMAIN MAINLY ISOLATED. THE WEAK ONSHORE TRAJECTORIES
AND ONSET OF THE SEA BREEZE LATE MORNING COULD KICK OFF ISOLATED
SHOWERS ALONG THE COAST BEFORE RISK FOR SPOTTY RAINS SHIFT INLAND
DURING THE AFTERNOON. WE MADE LITTLE IN THE WAY OF CHANGES TO OUR
POP/TEMP SCHEMES IN OUR FORECAST TODAY. WARMEST TEMPS OVER INLAND
GEORGIA ZONES SOLIDLY IN THE MID 90S. POPS GENERALLY IN THE 20
PERCENT RANGE.

TONIGHT...MAINLY DRY WEATHER ON TAP...PERHAPS AN ISOLATED SHOWER
AT THE BEACHES AND BARRIER ISLANDS AFTER MIDNIGHT AND ANOTHER CHANCE
FOR PATCHY FOG ACROSS INLAND AREAS TOWARD DAYBREAK SUNDAY.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY/...
SUNDAY AND SUNDAY NIGHT...THE CENTER OF THE UPPER RIDGE ALOFT AND
ASSOCIATED ANTICYCLONE WILL MOVE VERY LITTLE AND REMAIN NEARLY RIGHT
ON TOP OF THE FORECAST AREA. SIMILARLY...THE SURFACE PATTERN WILL
FEATURE ATLANTIC HIGH PRESSURE NOSING IN FROM THE EAST AND
CONTROLLING THE LOW LEVELS. MUCH OF THE FORECAST AREA WILL CONTINUE
TO SEE VERY DRY MID/UPPER LEVELS...THOUGH BETTER MOISTURE WILL EXIST
ACROSS SOUTHEAST GEORGIA IN THE AFTERNOON/EVENING HOURS. SOUNDINGS
SHOW A NOTABLE CAP IN THE 700-800 MB LAYER ACROSS THE SOUTH CAROLINA
ZONES. I HAVE NOT MADE ANY CHANGES TO THE POP FORECAST...WHICH STILL
FEATURES CHANCES POPS ACROSS SOUTHEAST GEORGIA AND ALONG THE
SAVANNAH RIVER...WITH ONLY SLIGHT CHANCES ELSEWHERE DURING PEAK
HEATING. OVERNIGHT...ANY LINGERING ACTIVITY WILL DIMINISH IN THE
EVENING WITH JUST SLIGHT CHANCES OVER THE COASTAL WATERS LATE. LOOK
FOR HIGHS IN THE LOW/MID 90S AND LOWS IN THE MID/UPPER 70S.

MONDAY THROUGH TUESDAY...THE PATTERN WILL REMAIN QUITE TYPICAL OF
SUMMERTIME WITH RIDGING ALOFT AND ATLANTIC HIGH PRESSURE AT THE
SURFACE. THROUGH THE EARLY WEEK PERIOD...THE UPPER RIDGE WILL BECOME
INCREASINGLY WEST/EAST ORIENTED AS IT RETROGRADES A BIT BACK TO THE
WEST. THE BELT OF WESTERLIES WILL REMAIN NORTH OF THE AREA...AS WELL
AS ANY EMBEDDED SHORTWAVES. THE ATMOSPHERE WILL GRADUALLY BE LESS
HOSTILE TO CONVECTIVE DEVELOPMENT AS MOISTURE IMPROVES ACROSS THE
REGION. HOWEVER...DUE TO THE LACK OF LARGER SCALE
FORCING...PRECIPITATION CHANCES WILL LARGELY BE DRIVEN BY
CONVERGENCE ALONG THE AFTERNOON SEA BREEZE AND SURFACE HEATING
PROCESSES. THIS WILL KEEP THE COVERAGE IN THE ISOLATED TO SCATTERED
RANGE EACH AFTERNOON AND EVENING. THE OVERALL SEVERE THREAT IS QUITE
LOW DURING THIS TIME...BUT AN ISOLATED SEVERE STORM CANNOT BE RULED
OUT DUE TO MESOSCALE BOUNDARY INTERACTIONS. TEMPERATURES WILL
CONTINUE TO BE ABOVE NORMAL WITH HIGHS IN THE LOW/MID 90S AND LOWS
IN THE MID/UPPER 70S.

&&

.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
LITTLE CHANGE WAS MADE TO THE GOING FORECAST IN THE LONG TERM
PERIOD. THE SOUTHEAST REGION WILL REMAIN UNDER THE INFLUENCE OF THE
RIDGE ALOFT...WHICH WILL ACTUALLY EXPAND BACK EASTWARD AND
STRENGTHEN IN THE MID/LATE TIME FRAME. ATLANTIC HIGH PRESSURE WILL
STILL BE THE PRIMARY SURFACE FEATURE AS IT EXTENDS WESTWARD ACROSS
THE FORECAST AREA. THERE ARE SOME INDICATIONS THAT A FRONT WILL
ATTEMPT TO APPROACH FROM THE NORTH LATE IN THE PERIOD...BUT GIVEN
THE OVERALL PATTERN THE EXPECTATION IS FOR IT TO REMAIN NORTH OF THE
AREA. ABOVE NORMAL TEMPERATURES ARE FORECAST THROUGH THE PERIOD.

&&

.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
THE VAST MAJORITY OF THE VALID TAF CYCLE AT KCHS AND KSAV WILL BE
VFR THROUGH 06Z SUNDAY. COULD SEE A FEW HOURS OF LOW STRATUS
AND/OR FOG WITH SUB-VFR CONDITIONS AT EITHER OR BOTH TERMINALS
FROM ABOUT 08-13Z SATURDAY. BUT THE WORST CONDITIONS LOOK TO STAY
INLAND FROM THE AIRSTRIPS WITH A SE AND SOUTH SYNOPTIC FLOW.
ISOLATED SHRA/TSRA MAY POSE A BRIEF CONCERN THIS AFTERNOON IN
ASSOCIATION WITH THE INLAND PENETRATING SEA BREEZE. BUT THERE IS
NO JUSTIFICATION TO INCLUDE ANYTHING AT THIS TIME.

EXTENDED AVIATION OUTLOOK...LOW CHANCES OF DIRECT IMPACTS FROM
ISOLATED SHOWERS/THUNDERSTORMS THROUGH EARLY NEXT WEEK. ALSO...LOW
CHANCES FOR EARLY MORNING FOG/STRATUS THROUGH EARLY NEXT WEEK.
OTHERWISE...MAINLY VFR.

&&

.MARINE...
A CONTINUATION OF FAIRLY TRANQUIL MARINE CONDITIONS TODAY AND TONIGHT.
LIGHT MOSTLY ONSHORE SE FLOW LESS THAN 15 KT AND SEAS 2 TO 3 FT.

SUNDAY THROUGH WEDNESDAY...ATLANTIC HIGH PRESSURE CENTERED TO THE
EAST OF THE LOCAL WATERS WILL BE THE PRIMARY FEATURE THROUGH THE
MIDDLE OF NEXT WEEK. THIS WILL DRIVE A PERSISTENT SOUTH TO SOUTHWEST
FLOW THROUGH MOST OF THE PERIOD. FOR MUCH OF THE PERIOD...WINDS WILL
BE LESS THAN 15 KT. THEY COULD INCREASE INTO THE 15-20 KT RANGE AT
TIMES...ESPECIALLY WITH THE AFTERNOON SEA BREEZE ALONG THE LAND/SEA
INTERFACE AND IN NOCTURNAL SURGES. SEAS WILL GENERALLY BE 2 FT
ACROSS THE NEARSHORE WATERS AND 2-3 FT FOR THE OUTER WATERS. OVERALL
CONDITIONS ARE EXPECTED TO STAY BELOW SMALL CRAFT ADVISORY
THRESHOLDS THROUGH THE PERIOD.

&&

.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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