Special Weather Statement, NWS Charleston, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
353 PM EDT THU AUG 16 2012

.SYNOPSIS...
AN INLAND TROUGH OF LOW PRESSURE WILL PREVAIL THROUGH FRIDAY.
ANOTHER WEAK COLD FRONT WILL APPROACH FROM THE NORTHWEST SATURDAY
BEFORE STALLING JUST NORTH AND WEST OF THE AREA ON SUNDAY AS A
WEAK WAVE OF LOW PRESSURE FORMS ALONG THE FRONT. THE FRONT IS
EXPECTED TO SHIFT ACROSS THE AREA EARLY NEXT WEEK...THEN LINGER
JUST OFFSHORE INTO THE MIDDLE OF NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
THE CONVECTION HAS CERTAINLY TAKEN OFF OVER OUR SOUTHERN AND
CENTRAL COASTAL REGION...SPARKED BY LOW LEVEL BOUNDARY COLLISIONS
AND A WEAK UPPER LEVEL SHORT WAVE MOVING ACROSS CENTRAL GA. HAVE
INCREASED POPS...BUT CONVECTION IS CHANGING IN COVERAGE SO
RAPIDLY...IT IS NEARLY IMPOSSIBLE TO GET THE POPS ALIGNED WITH
REALITY. HAVE ALREADY RECEIVED SEVERAL REPORTS OF LARGE HAIL WITH
THE STORMS AROUND THE SAVANNAH RIVER REGION. EXPECT STORMS TO
PROPAGATE NORTHWARD ALONG SEA BREEZE...WHICH IS PINNED VERY CLOSE
TO THE COAST. HOWEVER...NOT THINKING THE STORMS THAT DEVELOP
FURTHER NORTH WILL BE QUITE AS STRONG AS THE MORE SOUTHERN ONES
DUE TO LOWER CAPE VALUES. HOWEVER...LATEST RUC ANALYSES INDICATING
30-40 KTS OF BULK SHEAR NEAR THE COAST...WHICH COULD ALLOW
ORGANIZED UPDRAFTS AND LONGER LASTING STORMS MOVING UP THE COAST.

SCATTERED STORMS...WHICH SHOULD STAY CONFINED TO MAINLY THE
COASTAL THIRD OF THE REGION...WILL DISSIPATE BY THE EVENING...BUT
LIKELY LINGER OVER THE COASTAL WATERS WELL INTO THE EVENING. MIN
TEMPS GENERALLY IN THE LOWER TO MID 70S.

SOME GUIDANCE INDICATING MUCH MORE CLOUD COVER TONIGHT THAN
CURRENTLY ADVERTISED. WE DID BUMP CLOUD COVER UP FROM THE PREVIOUS
FORECAST...BUT IT MAY NEED TO BE ADJUSTED HIGHER. THERE MAY ALSO
NOW BE A THREAT FOR SOME FOG LATER TONIGHT AND EARLY FRIDAY
MORNING WITHIN AREAS THAT RECEIVED RAIN. HOWEVER...CONFIDENCE TOO
LOW TO MENTION IN FORECAST AT THIS TIME.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
THINK FRIDAY WILL BE QUIET THROUGH MID DAY AS A WEAK AREA OF
SUBSIDENCE MOVES THROUGH. THE SUBSIDENCE MAY ALLOW FOR A LOW CLOUD
DECK FOR A FEW HOURS IN THE EARLY MORNING HOURS...GRADUALLY
BREAKING UP BY MID DAY. I HAVE GONE JUST A TOUCH BELOW MAX TEMP
GUIDANCE BASED ON THE THINKING THAT THE CLOUDS MAY KEEP TEMPS DOWN
A SMIDGE BEFORE NOON. HOWEVER...THERE SHOULD BE PLENTY OF SUNSHINE
AROUND BY AFTERNOON...WITH JUST A FEW ISOLATED THUNDERSTORMS
POSSIBLE NEAR THE SEA BREEZE.

LATER IN THE DAY...THE LEE TROF WILL GET A LITTLE BOOST FROM A WEAK
SHORTWAVE AND BE A FOCUS FOR LATE DAY CONVECTION OVER INLAND
AREAS...PROBABLY LASTING INTO THE EVENING HOURS IN A FEW PLACES.

ON SATURDAY...CLOUDS AND AFTERNOON/EVENING THUNDERSTORMS WILL
INCREASE IN COVERAGE AS A RATHER ROBUST UPPER TROF SETS UP OVER THE
EASTERN HALF OF NORTH AMERICA. THE FRONT APPROACHING FROM THE
NORTHWEST WILL STALL OVER THE UPSTATE AS A WEAK AREA OF LOW PRESSURE
FORMS ALONG THE FRONT...GIVING US MOIST AND DEEP SOUTHWESTERLY FLOW.
PWS WILL INCREASE TO NEAR 2 INCHES...AND THE CYCLONIC FLOW ALOFT
WILL PROVIDE SUPPORT FOR DIURNAL CONVECTION ALONG ANY BOUNDARIES
THAT FORM.

THINGS WILL BE EVEN MORE UNSETTLED ON SUNDAY AS THE UPPER JET
STRETCHES OUT TO OUR NORTHWEST FROM THE LOWER MISSISSIPPI VALLEY ALL
THE WAY TO NEW ENGLAND. PWS SHOULD GO UP OVER 2 INCHES BY THEN...AND
THE SYNOPTIC LIFT WILL BE STRONGER. ONLY FACTOR THAT MAY HOLD BACK
CONVECTION IN A FEW PLACES IS THE LACK OF STRONG INSTABILITY AS
CLOUDS WILL KEEP MAXIMUM TEMPS DOWN A FEW DEGREES FROM SATURDAY.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
MEDIUM RANGE GUIDANCE IS IN GOOD AGREEMENT INDICATING AN UNSETTLED
PATTERN FOR MOST OF THE LONG TERM PERIOD WITH BROAD UPPER LEVEL
TROUGHING PERSISTING ACROSS THE EASTERN UNITED STATES THROUGH THE
MIDDLE OF NEXT WEEK. WHILE MODELS DIFFER SLIGHTLY WITH THE POSITION
OF A COLD FRONT ALONG THE SOUTHEAST COAST...THEY GENERALLY SUGGEST
THE FRONT SLOWLY SHIFTING ACROSS THE AREA ON MONDAY THEN STALLING
JUST OFFSHORE INTO THE MIDDLE OF NEXT WEEK. THE GREATEST CHANCES FOR
PRECIPITATION APPEAR TO BE EARLY IN THE WEEK WITH AN AXIS OF DEEP
MOISTURE OVER THE AREA AND THE FRONT PASSING THROUGH...BUT COULD
DIMINISH SOME TOWARD THE MIDDLE OF NEXT WEEK DEPENDING ON HOW FAR
OFFSHORE THE FRONT AND ASSOCIATED DEEP MOISTURE GET. OVERALL...THE
FORECAST WILL MAINTAIN A CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH
THE LONG TERM PERIOD. SLIGHTLY BELOW NORMAL TEMPERATURES ARE
EXPECTED THROUGH THE LONG TERM PERIOD.

&&

.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
CONVECTION HAS BLOSSOMED QUICKLY OVER KSAV DUE TO MULTIPLE
BOUNDARY COLLISIONS AND THE PRESENCE OF A WEAK UPPER LEVEL SHORT
WAVE. BRIEF PERIODS OF MVFR POSSIBLE THROUGH THE REST OF THE
AFTERNOON...THEN EXPECT A RETURN TO MAINLY VFR BY THIS EVENING.
CONVECTION STILL POSSIBLE AT KCHS...BUT COVERAGE EXPECTED TO BE
LESS THAN AROUND KSAV AND TIMING...IF IT OCCURS...WILL BE LATE
AFTERNOON AND EVENING. HAVE CONTINUED TO LEAVE OUT PRECIP MENTION
FOR KCHS GIVEN LOW PROBABILITIES OF IT HITTING THE TERMINAL...BUT
WILL CLOSELY MONITOR.

TONIGHT...VFR EXPECTED TO PREVAIL FOR MUCH OF THE NIGHT.
HOWEVER...STILL CONCERNED ABOUT A POTENTIAL FOR LOWER
CIGS...POSSIBLY MVFR/IFR FOR BOTH SITES MAINLY AFTER 08Z TONIGHT.
ALSO...GIVEN THE CONVECTION THIS AFTERNOON AND EVENING...FOG IS
MORE OF A POSSIBILITY...ESPECIALLY FOR KSAV. WILL NEED TO ADDRESS
THE FOG POTENTIAL WITH LATER UPDATES.

EXTENDED AVIATION OUTLOOK...THERE IS A CHANCE OF SOME LOW CLOUDS
AROUND EACH MORNING THROUGH THE WEEKEND...POSSIBLY ENOUGH TO LOWER
CIGS TO MVFR FOR AN HOUR OR TWO. OTHERWISE...SCATTERED SHOWERS AND
THUNDERSTORMS...MAINLY DURING THE AFTERNOON/EVENING HOURS...COULD
RESULT IN TEMPORARY REDUCTIONS IN CIGS/VSBYS THIS WEEKEND.

&&

.MARINE...
A WEAK SURFACE FRONT REMAINS STALLED INLAND THROUGH THIS EVENING.
SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO CONTINUE ALONG
THE COASTAL WATERS THROUGH THIS EVENING. SOME OF THESE STORMS
COULD BE STRONG WITH GUSTY WINDS NEAR 35 KTS AND SMALL HAIL.
ISOLATED SHOWERS AND THUNDERSTORMS WILL GRADUALLY TAPPER OFF LATER
TONIGHT. WINDS LESS THAN 15 KTS AND SEAS 3 FT OR LESS WILL PERSIST
THROUGH TONIGHT.

AFTER A RELATIVELY QUIET FRIDAY...A COLD FRONT WILL APPROACH FROM
THE NORTHWEST THROUGH THE WEEKEND...BEFORE STALLING JUST OFF THE
SOUTHEAST COAST EARLY NEXT WEEK. OVERALL...A SOUTH-SOUTHWEST FLOW
IS GENERALLY EXPECTED EACH DAY...WITH THE FLOW VEERING OFFSHORE
DURING THE NIGHTTIME/EARLY MORNING HOURS BY NEXT WEEK. BRIEF
SURGES UPWARDS OF NO MORE THAN 15-20 KT COULD OCCUR AT TIMES...BUT
WIND AND SEA CONDITIONS SHOULD REMAIN BELOW SMALL CRAFT ADVISORY
CRITERIA THROUGH THE PERIOD.

&&

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

&&

SYNOPSIS...
NEAR TERM...RFM
SHORT TERM...ALSHEIMER
LONG TERM...JAQ
AVIATION...BDC/RFM
MARINE...ALSHEIMER/RFM

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHARLESTON SC
356 AM EDT THU AUG 16 2012

AMZ330-350-352-354-374-GAZ087-088-099>101-114>119-137>141-SCZ040-
042>045-047>052-171130-
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-
356 AM EDT THU AUG 16 2012

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

.DAY ONE...TODAY AND TONIGHT.

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ASSISTANCE IS NOT ANTICIPATED AT THIS TIME.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHARLESTON SC
400 PM EDT THU AUG 16 2012

GAZ088-SCZ040-042-162045-
ALLENDALE-HAMPTON-SCREVEN-
400 PM EDT THU AUG 16 2012

...STRONG THUNDERSTORMS WILL IMPACT PORTIONS OF SCREVEN...ALLENDALE
AND HAMPTON COUNTIES THROUGH 445 PM EDT...

AT 353 PM EDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A
STRONG THUNDERSTORM...8 MILES NORTHWEST OF SHIRLEY...MOVING EAST AT
10 MPH.

SOME LOCATIONS THAT WILL BE AFFECTED INCLUDE...
ESTILL...FURMAN...GARNETT...LENA...LURAY...SCOTIA AND SHIRLEY...

PREPARE NOW FOR THE FOLLOWING HAZARDS...
GUSTY WINDS OF 40 TO 50 MPH...
PENNY SIZE HAIL...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

FREQUENT CLOUD-TO-GROUND LIGHTNING IS OCCURRING. POSTPONE OUTDOOR
ACTIVITIES PROMPTLY. SEEK SHELTER INSIDE AN ENCLOSED BUILDING.

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 3279 8105 3256 8129 3272 8149 3285 8141
TIME...MOT...LOC 2000Z 285DEG 10KT 3275 8138

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