Special Weather Statement, NWS Charleston, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
601 PM EDT WED AUG 29 2012

.SYNOPSIS...
DEEP TROPICAL MOISTURE WILL REMAIN IN PLACE ACROSS THE AREA
THROUGH THURSDAY BRINGING HIGHER THAN NORMAL RAIN CHANCES. A WEAK
COLD FRONT WILL PUSH THROUGH THE AREA FROM NORTH TO SOUTH LATE
THURSDAY AND THURSDAY NIGHT. WEAK HIGH PRESSURE WILL THEN SETTLE
OVER THE AREA FRIDAY AND SATURDAY...BEFORE A TROUGH OF LOW
PRESSURE APPROACHES FROM THE WEST LATE WEEKEND INTO EARLY NEXT
WEEK.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
UPDATED GRIDS/TEXT PRODUCTS TO TAKE CURRENT MESOSCALE TRENDS INTO
ACCOUNT. TWO AREAS OF CONCERN.

1. OUTFLOW MOVING SOUTH OUT OF ORANGEBURG COUNTIES IS POISED TO
INTERSECT THE SEA BREEZE SHORTLY. THE ATMOSPHERE IS QUITE MOIST
AND UNSTABLE ACROSS THE CHARLESTON TRI-COUNTY AREA WHICH WILL
LIKELY SUPPORT ADDITIONAL CONVECTIVE DEVELOPMENT AS LOW-LEVEL
CONVERGENCE MAXIMIZES. LOW/MID-LEVEL FLOW OFF KCLX VWP SUGGESTS
ANY DEEP CONVECTIVE CELLS THAT DEVELOP ALONG THE INTERSECTION WILL
MOVE EAST...POSSIBLY IMPACTING AREAS THAT SAW 4-8 INCHES OF RAIN
YESTERDAY INCLUDING DOWNTOWN CHARLESTON. COMPLICATING MATTERS IS
HIGH TIDE IS QUICKLY APPROACHING. THERE WILL CERTAINLY BE A
POTENTIAL FOR TRAINING AND WITH PWATS IN EXCESS OF 2.25 INCHES...
IT WILL NOT TAKE LONG FOR RAIN TO CAUSE FLOODING PROBLEMS ACROSS
THE CHARLESTON METRO AREA. THE FLASH FLOOD WATCH REMAINS IN EFFECT
FOR TIDAL BERKELEY AND CHARLESTON COUNTIES UNTIL 11 PM. INCREASED
POPS TO 70 PERCENT ACROSS NORTHERN HALF OF FORECAST AREA THROUGH
MID- EVENING.

2. CONVECTION MOVING QUICKLY NORTH FROM FAR SOUTHEAST GEORGIA IS
POISED TO CROSS THE ALTAMAHA RIVER. INCREASED POPS TO 80 PERCENT
FOR AREAS ROUGHLY SOUTH OF A CLAXTON-RICHMOND HILL LINE IT DOES
APPEAR MEASURABLE RAINFALL IS A GOOD BET FOR MANY OF THESE AREAS.
LOCALLY HEAVY RAINFALL WILL ALSO BE POSSIBLE...BUT THIS AREA CAN
TAKE A BIT MORE IN THE WAY OF RAIN PER LATEST FLASH FLOOD
GUIDANCE.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/...
ONE MORE DAY OF DEEP TROPICAL MOISTURE IS IN STORE FOR
THURSDAY...SUPPORTING SCATTERED AFTERNOON THUNDERSTORMS WITH
LOCALLY HEAVY RAIN. THE BEST CHANCE WILL GENERALLY BE SOUTH AND
WEST OF THE SAVANNAH RIVER...WITH DRYING SLOWLY WORKING INTO THE
SOUTH CAROLINA COUNTIES LATE IN THE DAY. PLENTIFUL CLOUD COVER
WILL KEEP MAX TEMPS IN THE MID 80S.

THURSDAY NIGHT A WEAK BACKDOOR COLD FRONT WILL PUSH IN FROM THE
NORTH AND MOVE THROUGH RATHER QUICKLY...BRINGING IN DRIER AIR.

FRIDAY WILL BE MUCH SUNNIER...AND HENCE WARMER EVEN THOUGH THE AREA
WILL BE BEHIND A COLD FRONT. THERE WILL STILL BE A SLIGHT CHANCE OF
AFTERNOON THUNDERSTORMS...MAINLY WEST OF INTERSTATE 95...BUT THE
COVERAGE WILL BE LOWER THAN THE PAST COUPLE OF DAYS. GFS HOLDS ON TO
DEEPER MOISTURE OVER INTERIOR GEORGIA...BUT FOR NOW I PREFER THE
DRIER SOLUTION OF THE NAM12 BASED ON THE 50S DEW POINTS BEHIND THE
FRONT IN VIRGINIA TODAY. OUR DEW POINTS CERTAINLY WONT GET THAT
LOW...BUT IT INDICATES THE AIR IS REASONABLY DRY FOR LATE AUGUST.

MOSTLY SUNNY WEATHER WILL CONTINUE INTO SATURDAY...AND TEMPS MAY
EVEN BE A DEGREE OR TWO WARMER AS HEIGHTS BUILD A BIT ALOFT.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AFTER A RAIN-FREE NIGHT SATURDAY NIGHT...HIGH PRESSURE AT THE
SURFACE AND ALOFT WILL WEAKEN/RETREAT OFFSHORE...ALLOWING A TROUGH
OF LOW PRESSURE AT THE SURFACE/ALOFT AND ASSOCIATED DEEP LAYER
MOISTURE TO DEVELOP OVER THE SOUTHEAST. WHILE GUIDANCE DIFFERS
CONCERNING DETAILS OF THE TROUGH DEPTH/POSITION AND THE
MAGNITUDE/EXPANSE OF THE ASSOCIATED PLUME OF MOISTURE...OVERALL
TRENDS POINT TOWARD INCREASING POPS SUNDAY THROUGH THE MIDDLE OF
NEXT WEEK. TEMPERATURES SHOULD AVERAGE CLOSE TO NORMAL BUT WILL
DEPEND GREATLY ON CLOUD COVER/PRECIPITATION.

&&

.AVIATION /22Z WEDNESDAY THROUGH MONDAY/...
MVFR CIGS/VSBYS ARE POSSIBLE THIS EVENING AT BOTH TERMINALS WITH
SHOWERS AND/OR THUNDERSTORMS WHILE DEEP MOISTURE REMAINS OVER THE
AREA...MAINLY THROUGH 00Z. SHOWERS AND/OR THUNDERSTORMS SHOULD
WANE AFTER DARK. LOW LEVEL MOISTURE WILL AGAIN PROVIDE CONDITIONS
FAVORABLE FOR SUB-VFR CONDITIONS BETWEEN 09Z-14Z THURSDAY...BUT
CONFIDENCE IN STARTING TIME AND DURATION IS TOO LOW TO JUSTIFY
PREVAILING SUB-VFR CONDITIONS AT THIS TIME.

EXTENDED AVIATION OUTLOOK...THURSDAY THE TERMINALS WILL STILL BE
SUSCEPTIBLE TO SOME MVFR CIGS...ESPECIALLY SAV...IN THE DEEP
MOISTURE. THERE COULD ALSO BE REDUCED CIGS/VSBYS IN THUNDERSTORMS
THURSDAY AFTERNOON. CONDITIONS SHOULD IMPROVE SIGNIFICANTLY FRIDAY
INTO THE WEEKEND WITH A BUBBLE OF HIGH PRESSURE SETTING UP OVER THE
AREA. ONLY ISOLATED THUNDERSTORMS ARE EXPECTED THIS WEEKEND.

&&

.MARINE...
TONIGHT...WINDS/SEAS WILL REMAIN WELL BELOW SMALL CRAFT ADVISORY
THRESHOLDS WITH A WEAK PRESSURE GRADIENT OVER THE COASTAL WATERS.
IN GENERAL WINDS WILL REMAIN BETWEEN 5-10 KNOTS WITH THE EXCEPTION
OF OCCASIONAL 15 KNOT WINDS BEYOND 20 NM. SEAS BETWEEN 2-4 FEET
WILL GRADUALLY SUBSIDE OVERNIGHT.

WINDS WILL BE LESS THAN 15 KNOTS AWAY FROM CONVECTION THURSDAY
THROUGH SUNDAY WITH SEAS MAINLY 2 FEET IN THE NEARSHORE WATERS AND
2 OR 3 FEET IN THE OFFSHORE GEORGIA WATERS. WINDS AND SEAS MAY
PICK UP A TOUCH SUNDAY NIGHT AND MONDAY AS THE PRESSURE GRADIENT
TIGHTENS UP...BUT CONDITIONS SHOULD STILL BE WELL BELOW SCA
CRITERIA.

RIP CURRENTS...DUE TO THE AFFECTS OF THE APPROACHING FULL
MOON...LINGERING SWELL ENERGY...AND LIGHT ONSHORE FLOW...A
MODERATE RISK OF RIP CURRENTS WILL CONTINUE UNTIL THIS EVENING.

&&

.TIDES/COASTAL FLOODING...
MODELS SUGGEST POSITIVE TIDAL ANOMALIES OF UP TO ONE HALF FOOT
THROUGH MID-LATE WEEK AND THIS COULD LEAD TO SHALLOW SALTWATER
FLOODING DURING THE TIME OF THE EVENING HIGH TIDES. THE SITUATION
COULD BECOME ENHANCED IF HEAVY RAINFALL OCCURS DURING THE HIGH
TIDE...ESPECIALLY IN THE NORMALLY FLOOD-PRONE AREAS SUCH AS
DOWNTOWN CHARLESTON AND SAVANNAH.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...FLASH FLOOD WATCH UNTIL 11 PM EDT THIS EVENING FOR SCZ050-052.
MARINE...NONE.

&&

SYNOPSIS...
NEAR TERM...
SHORT TERM...ALSHEIMER
LONG TERM...ALSHEIMER
AVIATION...ALSHEIMER/DPB
MARINE...ALSHEIMER/DPB
TIDES/COASTAL FLOODING...

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHARLESTON SC
315 PM EDT WED AUG 29 2012

SCZ050-301915-
CHARLESTON-
315 PM EDT WED AUG 29 2012

...FLASH FLOOD WATCH IN EFFECT UNTIL 11 PM EDT THIS EVENING...
...MODERATE RISK FOR RIP CURRENTS IN EFFECT UNTIL 8 PM EDT THIS
EVENING...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST SOUTH CAROLINA.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   FLASH FLOOD WATCH.
   MODERATE RISK FOR RIP CURRENTS.

COASTAL HAZARDS...REGARDLESS OF WHETHER RAIN IS FALLING...AN
ELEVATED HIGH TIDE COULD PRODUCE SHALLOW SALT WATER FLOODING
THIS EVENING. A COASTAL FLOOD ADVISORY COULD EVENTUALLY BE
REQUIRED.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.

FLOODING...LOCALLY HEAVY RAINFALL AND LOCALIZED FLOODING COULD
OCCUR THURSDAY... ESPECIALLY IN LOCATIONS IN AND AROUND WEST
ASHLEY...DOWNTOWN CHARLESTON...NORTH CHARLESTON AND MOUNT
PLEASANT.

COASTAL HAZARDS...ELEVATED TIDES WILL CONTINUE AND COULD PRODUCE
SHALLOW SALT WATER FLOODING AROUND THE TIMES OF HIGH TIDE EACH
EVENING THROUGH LATE WEEK.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ASSISTANCE IS NOT ANTICIPATED AT THIS TIME.

GAZ087-088-099>101-114>116-118-137-138-140-SCZ040-042>045-047-301915-
JENKINS-SCREVEN-CANDLER-BULLOCH-EFFINGHAM-TATTNALL-EVANS-
INLAND BRYAN-INLAND CHATHAM-LONG-INLAND LIBERTY-INLAND MCINTOSH-
ALLENDALE-HAMPTON-INLAND COLLETON-DORCHESTER-INLAND BERKELEY-
INLAND JASPER-
315 PM EDT WED AUG 29 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST GEORGIA AND
SOUTHEAST SOUTH CAROLINA.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

HEAVY RAINFALL...PERIODS OF HEAVY RAINFALL WITH LOCALIZED FLOODING
COULD OCCUR TODAY.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.

HEAVY RAINFALL...PERIODS OF HEAVY RAINFALL WITH LOCALIZED FLOODING
COULD OCCUR THURSDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ASSISTANCE IS NOT ANTICIPATED AT THIS TIME.

AMZ330-350-352-354-374-301915-
CHARLESTON HARBOR-
WATERS FROM SOUTH SANTEE RIVER TO EDISTO BEACH SC OUT 20 NM-
WATERS FROM EDISTO BEACH SC TO SAVANNAH GA OUT 20 NM-
WATERS FROM SAVANNAH GA TO ALTAMAHA SOUND GA OUT 20 NM...INCLUDING
GRAYS REEF NATIONAL MARINE SANCTUARY-
WATERS FROM SAVANNAH GA TO ALTAMAHA SOUND GA EXTENDING FROM 20 TO
60 NM-
315 PM EDT WED AUG 29 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR ATLANTIC COASTAL WATERS.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ASSISTANCE IS NOT ANTICIPATED AT THIS TIME.

GAZ117-119-139-141-SCZ048-049-051-301915-
COASTAL BRYAN-COASTAL CHATHAM-COASTAL LIBERTY-COASTAL MCINTOSH-
BEAUFORT-COASTAL COLLETON-COASTAL JASPER-
315 PM EDT WED AUG 29 2012

...MODERATE RISK FOR RIP CURRENTS IN EFFECT UNTIL 8 PM EDT THIS
EVENING...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST GEORGIA AND
SOUTHEAST SOUTH CAROLINA.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   MODERATE RISK FOR RIP CURRENTS.

HEAVY RAINFALL...PERIODS OF HEAVY RAINFALL WITH LOCALIZED FLOODING
COULD OCCUR TODAY.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.

HEAVY RAINFALL...PERIODS OF HEAVY RAINFALL WITH LOCALIZED FLOODING
COULD OCCUR THURSDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ASSISTANCE IS NOT ANTICIPATED AT THIS TIME.

SCZ052-301915-
TIDAL BERKELEY-
315 PM EDT WED AUG 29 2012

...FLASH FLOOD WATCH IN EFFECT UNTIL 11 PM EDT THIS EVENING...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST SOUTH CAROLINA.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   FLASH FLOOD WATCH.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.

HEAVY RAINFALL...PERIODS OF HEAVY RAINFALL WITH LOCALIZED FLOODING
COULD OCCUR THURSDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ASSISTANCE IS NOT ANTICIPATED AT THIS TIME.