Special Weather Statement, NWS Charleston, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
357 PM EDT WED JUN 29 2011

.SYNOPSIS...
A WEAK COLD FRONT WILL MOVE INTO THE AREA TONIGHT...THEN STALL
AND GRADUALLY DISSIPATE OVER THE AREA ON THURSDAY...AS WEAK HIGH
PRESSURE BUILDS IN FROM THE NORTH. ATLANTIC HIGH PRESSURE WILL
THEN BUILD OVER THE REGION THIS WEEKEND INTO EARLY NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
CONVECTIVE TEMPERATURE WAS REACHED AROUND 2 PM THIS
AFTERNOON...AND CONVECTION FIRED UP ACCORDINGLY. MAIN THREAT
THROUGH THE EVENING HOURS WILL BE LOCALLY HEAVY RAIN AS CELLS MOVE
SLOWLY. THERE STILL COULD BE AN ISOLATED WET MICROBURST...BUT
WIDESPREAD SEVERE WEATHER IS NOT EXPECTED.

THE ACTIVITY SHOULD GRADUALLY MOVE SOUTHWARD AND SLOWLY DISSIPATE
AFTER SUNSET...ALTHOUGH THERE STILL COULD BE SOME CONVECTION IN THE
FAR SOUTHERN ZONES UNTIL MIDNIGHT. CHANCES LOOK PRETTY SLIM OVERNIGHT.

THE OTHER ISSUE TO CONSIDER IS FOG. NORMALLY I WOULD THINK THAT
FOG WOULD BE TOUGH TO COME BY WITH DEW POINTS IN THE 70S...BUT AN
EXTENDED PERIOD OF LIGHT WINDS OVER THE INTERIOR...ALONG WITH WET
GROUND IN MANY PLACES FROM THIS EVENINGS RAIN...COULD CREATE SOME
ISSUES HERE AND THERE. STILL...I DONT THINK IT WILL BE WIDESPREAD
ENOUGH TO MENTION IN THE ZONES.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/...
A STATIONARY FRONT WILL GRADUALLY DISSIPATE OVER THE FORECAST
AREA THURSDAY...WITH WEAK HIGH PRESSURE SETTING UP TO THE NORTH.
A BAND OF DEEP MOISTURE ASSOCIATED WITH A DEPARTING SHORTWAVE WILL
CONTINUE TO SHIFT SOUTHEAST OF THE AREA ON THURSDAY...AND MODEL
SOUNDINGS INDICATE PWAT VALUES DECREASING TO 1.5 INCHES
ACCORDINGLY. EXPECT LESS SHOWER/THUNDERSTORM COVERAGE THURSDAY
AFTERNOON...WITH CONVECTION MAINLY DRIVEN BY MOISTURE CONVERGENCE
ALONG THE SEABREEZE AND DISSIPATING SYNOPTIC BOUNDARY. WILL
MAINTAIN JUST A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS
THURSDAY AFTERNOON AND EVENING GENERALLY ALONG AND JUST INLAND OF
THE SEABREEZE.

THE AXIS OF A WEAK UPPER TROUGH WILL MOVE OFF THE COAST ON
FRIDAY...WHILE A LIGHT PRESSURE PATTERN AT THE SURFACE PREVAILS.
BOTH THE 12Z GFS AND 12Z NAM SOLUTIONS DEPICT AT LEAST ISOLATED
SHOWERS AND THUNDERSTORMS DEVELOPING ACROSS INLAND ZONES FRIDAY
AFTERNOON...LIKELY A RESULT OF WEAK SHORTWAVE ENERGY TRACKING
ALONG THE EASTERN PERIPHERY OF AN UPPER RIDGE IN THE OHIO AND
TENNESSEE VALLEYS. MODEL SOLUTIONS HINT THAT ANOTHER WEAK SURFACE
BOUNDARY COULD DEVELOP UPSTREAM...PROVIDING AN ADDITIONAL FOCUS FOR
MOISTURE CONVERGENCE WITH THE SEABREEZE BY LATE FRIDAY AFTERNOON.
HAVE ADDED JUST A SLIGHT CHANCE FOR CONVECTION AWAY FROM THE COAST
DURING THE FAVORED AFTERNOON AND EARLY EVENING HOURS.

THE UPPER RIDGE TO THE WEST WILL STEADILY BUILD TOWARD THE COAST
OVER THE WEEKEND. RISING HEIGHTS ALOFT AND INCREASING SUBSIDENCE
WILL LIKELY SUPPRESS CONVECTIVE DEVELOPMENT ON SATURDAY...AND WILL
THUS CONTINUE WITH A DRY FORECAST AT THIS TIME.

EXPECT A STEADY WARMING TREND THURSDAY THROUGH SATURDAY...AS A
RESULT OF GRADUALLY BUILDING HIGH PRESSURE ALOFT. HIGH TEMPERATURES
ON THURSDAY WILL REACH THE LOWER 90S AWAY FROM THE LOCALLY COOLER
COAST...WHILE TEMPERATURES COULD PEAK IN THE MID TO UPPER 90S
INLAND BY SATURDAY. MILD LOW TEMPERATURES WILL RANGE FROM AROUND
69 DEGREES INLAND TO THE MID 70S ALONG THE COAST.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
A DRY FORECAST WILL PERSIST THROUGH SUNDAY...AS ATLANTIC HIGH
PRESSURE BUILDS OVER THE SOUTHEAST. TEMPS WILL GRADUALLY WARM INTO
THE LOW/MID 90S SUNDAY AND REMAIN A FEW DEGREES ABOVE NORMAL
THROUGH MIDWEEK...AS MID LVL RIDGING BECOMES CENTERED OVER THE
MID ATLANTIC AND SOUTHEASTERN STATES AND ATLANTIC HIGH PRESSURE
CONTINUES TO DOMINATE OVER THE FORECAST AREA. OVERNIGHT LOWS WILL
BE THE LOW 70S...WITH MID/UPPER 70S ALONG THE IMMEDIATE COAST.
SLIGHT CHANCE POPS WILL GRADUALLY INCREASE MONDAY THROUGH
WEDNESDAY AS LIGHT ONSHORE FLOW RETURNS BOUNDARY LAYER MOISTURE
OVER THE REGION AND LEE SIDE TROUGHING IS ENHANCED BY ANOTHER WEAK
SFC TROUGH SHIFTING SLOWLY THROUGH THE NORTHEAST.

&&

.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
ISOLATED CONVECTION MAY IMPACT THE TERMINALS IN THE PERIOD
BETWEEN 21Z AND 00Z...BUT I AM NOT CONFIDENT ENOUGH AT THIS POINT
TO LOCK IN A SPECIFIC TIME OR VSBY/CIG...SO I WILL JUST LEAVE IN A
CB FOR NOW. IT LOOKS LIKE THE CHANCE WILL BE A LITTLE BETTER IN
SAV THAN CHS.

OVERNIGHT...THERE STILL SEEMS TO BE A SMALL CHANCE OF SOME MVFR
WHEN THE WINDS CALM DOWN...ESPECIALLY IF THERE IS RAIN AT THE
SITES THIS AFTERNOON OR EVENING. THERE ARE TOO MANY CONDITIONS
AT THIS TIME TO BRING THE VSBY ANY LOWER THAN 6 MILES...HOWEVER.
LATER SHIFTS WILL RE-EVALUATE.

EXTENDED AVIATION OUTLOOK...MAINLY VFR

&&

.MARINE...
WINDS AND SEAS HAVE CERTAINLY COME DOWN FOR EARLY THIS
MORNING...BASED MAINLY ON TYPICAL SUMMER DIURNAL TRENDS. I DO
EXPECT ANOTHER SURGE OVER THE WATERS THIS EVENING INTO THE
OVERNIGHT HOURS...BUT SURFACE PRESSURE GRADIENT WILL NOT BE AS
STRONG AS LAST NIGHT...SO I HAVE KEPT WINDS A TOUCH LOWER. NO
SCA EXPECTED.

FAIRLY BENIGN MARINE CONDITIONS WILL PERSIST THURSDAY THROUGH
EARLY NEXT WEEK...AS ATLANTIC HIGH PRESSURE BUILDS OVER THE
WESTERN ATLANTIC. WINDS AND SEAS ARE EXPECTED TO REMAIN WELL BELOW
SMALL CRAFT ADVISORY CRITERIA...WITH SEAS GENERALLY BETWEEN 2 TO
3 FT AND WINDS AT OR BELOW 15 KT. HIGHEST WINDS WILL REMAIN ALONG
THE COAST DURING AFTERNOON SEABREEZE CIRCULATIONS THIS WEEKEND.
SOUTH/SOUTHWEST WINDS MAY APPROACH 15 TO 20 KNOTS FOR WATERS
BEYOND 20 NM DURING NOCTURNAL SURGES EARLY NEXT WEEK.

&&

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

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHARLESTON SC
412 AM EDT WED JUN 29 2011

AMZ330-350-352-354-374-GAZ087-088-099>101-114>119-137>141-SCZ040-
042>045-047>052-300815-
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-JENKINS-SCREVEN-CANDLER-BULLOCH-EFFINGHAM-TATTNALL-EVANS-
INLAND BRYAN-COASTAL BRYAN-INLAND CHATHAM-COASTAL CHATHAM-LONG-
INLAND LIBERTY-COASTAL LIBERTY-INLAND MCINTOSH-COASTAL MCINTOSH-
ALLENDALE-HAMPTON-INLAND COLLETON-DORCHESTER-INLAND BERKELEY-
INLAND JASPER-BEAUFORT-COASTAL COLLETON-CHARLESTON-COASTAL JASPER-
TIDAL BERKELEY-
412 AM EDT WED JUN 29 2011

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

.DAY ONE...TODAY AND TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

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

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

33

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHARLESTON SC
406 PM EDT WED JUN 29 2011

SCZ048-051-292045-
BEAUFORT-COASTAL JASPER-
406 PM EDT WED JUN 29 2011

...STRONG THUNDERSTORMS WILL IMPACT PORTIONS OF JASPER AND BEAUFORT
COUNTIES THROUGH 445 PM EDT...

AT 403 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM...NEAR CLARENDON...MOVING SOUTHEAST AT 10 MPH.

SOME LOCATIONS THAT WILL BE AFFECTED INCLUDE...
BEAUFORT MARINE CORPS AIR STATION...BURTON...CLARENDON...DALE...
GARDENS CORNER...LAUREL BAY...LEMON ISLAND AND SHELDON...

PREPARE NOW FOR THE FOLLOWING HAZARDS...
STRONG WINDS OF 45 TO 55 MPH...
DIME SIZE HAIL...
FREQUENT CLOUD TO GROUND LIGHTNING...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

BE ALERT FOR RAPIDLY CHANGING WEATHER CONDITIONS AS STORMS APPROACH.
BE READY TO TAKE IMMEDIATE ACTION IN CASE A SEVERE THUNDERSTORM
WARNING IS ISSUED FOR YOUR LOCATION.

&&

LAT...LON 3235 8081 3251 8084 3252 8084 3252 8085
      3253 8085 3254 8084 3256 8084 3260 8083
      3261 8085 3265 8080 3249 8060
TIME...MOT...LOC 2006Z 320DEG 7KT 3252 8081

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHARLESTON SC
418 PM EDT WED JUN 29 2011

GAZ140-141-292045-
COASTAL MCINTOSH-INLAND MCINTOSH-
418 PM EDT WED JUN 29 2011

...STRONG THUNDERSTORMS WILL IMPACT PORTIONS OF MCINTOSH COUNTY
THROUGH 445 PM EDT...

AT 415 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM...NEAR VALONA...MOVING SOUTHEAST AT 5 MPH.

SOME LOCATIONS THAT WILL BE AFFECTED INCLUDE...
BLACKBEARD ISLAND...CARNIGAN...COX...CRESCENT...DARIEN...EULONIA...
MERIDIAN...PINE HARBOR...RIDGEVILLE...SAPELO ISLAND...SHELLMAN
BLUFF...TOWNSEND...VALONA AND WOLF ISLAND...

PREPARE NOW FOR THE FOLLOWING HAZARDS...
GUSTY WINDS OF 40 TO 50 MPH...
LOCALLY HEAVY RAIN IN EXCESS OF 2 INCHES PER HOUR...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS THUNDERSTORM IS CAPABLE OF PRODUCING VERY HEAVY RAIN...WHICH MAY
FLOOD DITCHES AND LOW-LYING AREAS. REDUCE VEHICLE SPEED TO LOWER THE
RISK OF HYDROPLANING. DO NOT DRIVE INTO PLACES WHERE WATER COVERS THE
ROAD. SEEK AN ALTERNATE ROUTE.

BE ALERT FOR RAPIDLY CHANGING WEATHER CONDITIONS AS STORMS APPROACH.
BE READY TO TAKE IMMEDIATE ACTION IN CASE A SEVERE THUNDERSTORM
WARNING IS ISSUED FOR YOUR LOCATION.

&&

LAT...LON 3131 8136 3131 8139 3130 8139 3134 8149
      3151 8163 3165 8145 3154 8117 3147 8119
      3140 8125 3137 8124 3137 8127 3134 8127
      3131 8125 3129 8129
TIME...MOT...LOC 2018Z 314DEG 2KT 3145 8133