High Surf Advisory 5, NWS Charleston, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1020 PM EST MON NOV 20 2006

...MAJOR COASTAL STORM DEVELOPING OFF THE SC/GA COAST...
...HIGH WINDS COULD IMPACT BRIDGE TRAVEL TUE MORNING...

.SHORT TERM /TONIGHT/...EVNG WATER VAPOR IMGRY SHOWS A HIGHLY
ANOMALOUS STRONG UPR TROF DIGGING ACROSS THE SERN U.S. WITH THE
CLOUD SHIELD OFF THE SE COAST EXHIBITING A CLASSIC BAROCLINIC LEAF
APPEARANCE. UNDER THE BAROCLINIC LEAF...COASTAL CYCLOGENESIS IS
UNDERWAY WITH LOW PRES NOTED ABOUT 125 MILES EAST OF TYBEE ISLAND
GA. SFC PRESSURES NEAR THE CENTER OF THE LOW HAVE DROPPED ABOUT 2MB
IN THE PAST SEVERAL HOURS AND SFC PRESSURES ACROSS THE NC/SC/GA
PIEDMONT HAVE RISEN ABOUT 2-3MB. THIS HAS PRODUCED A 3-5MB PRESS
GRADIENT ALONG THE SC COAST OVR THE LAST HOUR OR SO. WINDS HAVE
RESPONDED AND ARE NOW GUSTING 35 MPH AT MANY COASTAL OBSERVATION
STATIONS FROM TYBEE ISLAND NE ALONG THE SC COAST. THE PRES GRADIENT
WL CONTINUE TO TIGHTEN INTO TUE AS LOW PRESS DEEPENS AND STRONG HIGH
PRES BUILDS E TO THE APPALACHIAN CHAIN. IT SHOULD BE NOTED THAT THE
SFC LOW IS ALREADY A FEW MB LOWER THAN WHAT ANY OF THE 12Z/18Z MODEL
SUITE PREDICTED.

CONDITIONS WL CONTINUE TO DETERIORATE ACROSS THE RGN OVRNGT AS THE
LOW PRESS DEEPENS INTO A FORMIDABLE COASTAL STORM AS IT MEANDERS
WELL E OF THE SAVANNAH RIVER ENTRANCE. THE LATEST RUC OUTPUT
SUGGESTS A DEFORMATION ZONE WL SET UP ACROSS COASTAL NC AND SC
TOWARDS SUNRISE AS THE UPR TROF ALOFT BECOMES CUT OFF. SATL TRENDS
SUGGEST THIS PROCESS IS ALREADY UNDERWAY WITH CLOUD TOPS COOLING OFF
THE SC COAST SO EXPECT PCPN TO BLOSSOM ACROSS THE COAST LTE TNGT AS
MID-LVL FRONTOGENETICAL FORCING IN THE DEFORMATION ZONE INCRS. WL
MAKE A FEW MINOR CHANGES IN THE FCST TO BETTER TIME THE BEST CHANCES
RAIN TNGT BUT AT THIS POINT ITS PROBABLY NOT A GOOD IDEA TO CHANGE
THE OVRNGT POP FCST TOO MUCH UNTIL MORE DEFINITIVE PCPN TRENDS CAN
BE ESTABLISHED. IT IS POSSIBLE THAT MUCH OF INTERIOR SE GA WL REMAIN
DRY TNGT. FCST SOUNDINGS STILL SUGGEST LTL IN THE WAY OF P-TYPE
PROBLEMS WL OCCUR WITH THE ONSET OF PCPN. ALTHOUGH MOST OF THE
COLUMN WL REMAIN BELOW FREEZING...THE NEAR SFC LAYER /SFC-2000 FT/
JUST LOOKS TOO WARM TO SUPPORT ANY FROZEN HYDROMETERS.

WINDS WILL CONTINUE TO INCR TNGT...ESP AT THE COAST. WINDS NEAR THE
COAST ARE ALREADY NEARING WIND ADVISORY CRITERIA BUT AS BNDRY
LYR-950MB WINDS INCR TO NEAR 40-50 KT...SFC WINDS SHOULD RISE INTO
THE 25-35 MPH RANGE BY SUNRISE...ESP AT THE COAST. WE ARE BECMG
INCREASINGLY CONCERNED THAT HIGH WINDS JUST OFF THE SFC COULD
SEVERELY IMPACT BRIDGE OPERATIONS TUE MRNG...PARTICULARLY ON
ELEVATED BRIDGES SUCH AS THE RAVENEL BRIDGE IN CHARLESTON. A HIGH
WIND WARNING MAY EVENTUALLY BE NEEDED FOR ALL COASTAL COUNTIES.
&&

.MARINE...WINDS AND SEAS ARE QUICKLY BUILDING ACROSS THE WTRS. GALES
ARE NOW BEING REPORTED AT 41004 AND THE CAPERS MID-SHELF BUOY WITH
GUSTS TO NEAR GALE FORCE AT 41008. 00Z RUC GUIDANCE SHOWS BNDRY
LYR-950MB WINDS INCRG TO 40-50 AFT MIDNIGHT WITH 45-60 KT ACROSS THE
GA OFFSHORE WTRS. MODIFIED SOUNDINGS SUGGEST A LARGE PERCENTAGE OF
THIS SHOULD MIX TO THE SFC. PLAN ON INCRG WINDS TO 35 KT WITH GUSTS
TO 40 KT OVR THE GA NEARSHORE WATERS...30-40 KT WITH STORM FORCE
GUSTS TO 50 KT ACROSS THE SC NEARSHORE WATERS AND BRING WINDS UP TO
35-45 KT WITH GUSTS TO 55 KT OVR THE GA OFFSHORE WATERS. VERY
DANGEROUS MARINE CONDITIONS WL OCCUR...PARTICULARLY ACROSS THE
EASTERN HALF OF THE GA OFFSHORE WATERS WHERE THE WRN WALL OF THE
GULF STREAM CURRENTLY RESIDES. GALE AND STORM WARNINGS WL REMAIN BUT
WL UPGRADE THE GALE WARNING TO A STORM WARNING FOR THE SC NEARSHORE
WATERS.
&&

.AVIATION...DEVELOPING LOW OVER COASTAL WATERS IS EXPECTED TO CREATE
DETERIORATING WEATHER CONDITIONS FOR BOTH TERMS LATER TONIGHT/EARLY
MORNING. EXPECT MOISTURE AND ASSOCIATED CLOUDS TO WRAP AROUND LOW
LEADING TO MVFR CONDITIONS BY 06Z. WIND GUSTS REMAIN A HAZARD AS
DEEPENING LOW LEADS TO A STRONGER PRESSURE GRADIENT OVER THE
CAROLINAS AND CAA ALOFT ALLOWS MIXING OF STRONGER WINDS TO THE
SFC. WINDS SHOULD INCREASE TO 15 KNOTS WITH GUSTS UP TO 30 KNOTS AT
CHS AND 25 KNOTS AT SAV OVER NIGHT. AS DEEP LAYER OF MOISTURE WRAPS
AROUND LOW...EXPECT LIGHT RAIN TO DEVELOP AROUND 08Z THRU THE REST
OF THE TAF PERIOD.  MOS HINTS AT LOWERING CLOUD CEILINGS AND VSBYS
IN THE AFTERNOON BUT GIVEN SOME UNCERTAINTY OF RAIN INTENSITY
TOMORROW AFTERNOON...HAVE DECIDED TO KEEP CEILINGS AT LOW END MVFR
CONDITIONS TOWARDS THE END OF TAF PERIOD.
&&

.LAKE WINDS...WINDS ALREADY 20-25 KT ON THE OPEN LAKE WATERS BASED
ON OBSERVATIONS OUT OF THE CHARLESTON HARBOR. UNFORTUNATELY THE ONE
SENSOR WE HAVE ON THE SANTEE DAM IS NOT COMPLETELY SAMPLING THE WIND
SINCE WINDS ARE FROM THE NE /FROM OVER LAND/. STEEP LAPSE RATES AND
WINDS OF 40-45 KT IN THE BNDRY LYR SUGGEST SFC WNDS OF AT LEAST
30-35 KT. WL UPGRADE THE LAKE WIND ADVISORY TO A LOW-END HIGH WIND
WARNING. EXPECT WAVES IN THE OPEN WATERS TO REACH 4-5 FT AT TIMES...
PARTICULARLY ON THE SRN END OF THE LAKE. THIS MAY RESULT IN MINOR
LAKE FLOODING...EROSION AND POSSIBLE PIER/DOCK DAMAGE ON THE SRN END
OF THE LAKE...INCLUDING THE COMMUNITY OF PINOPOLIS.
&&

.COASTAL IMPACTS...SEAS AT 41004 HAVE RISEN TO AT LEAST 10 FT. SEAS
WL BUILD TO AT LEAST 8-10 FT IN THE 0-20 NM STRETCH BY SUNRISE AS
GALE FORCE WINDS WITH STORM FORCE GUSTS DVLP. DESPITE OFFSHORE
WINDS...BACKSWELL WITH 8-9 SEC PERIODS WL LIKELY PRODUCE
CONSIDERABLE BEACH EROSION...ESPECIALLY IN EROSION PRONE AREAS SUCH
AS TYBEE ISLAND...HUNTING ISLAND...EDISTO BEACH...FOLLY BEACH AND
WILD DUNES. WL GO AHEAD AND ISSUE A HIGH SURF ADVISORY.
&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...HIGH SURF ADVISORY FOR GAZ117-119-139-142 THROUGH TUE AFTERNOON.
  ...WIND ADVISORY FOR GAZ117-119-139-141 THROUGH TUE NIGHT.
SC...WIND ADVISORY FOR SCZ048>051 THROUGH TUE NIGHT.
  ...HIGH WIND WARNING FOR LAKE MOULTRIE SCZ045 THROUGH TUE
     AFTERNOON.
MARINE...STORM WARNING FOR AMZ350-352-374
         GALE WARNING FOR AMZ330-354.

&&

ST/DPB

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE CHARLESTON SC
600 PM EST MON NOV 20 2006

AMZ330-350-352-354-374-GAZ087-088-099>101-114>119-137>141-SCZ040-
042>045-047>051-211100-
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-BERKELEY-INLAND
JASPER-BEAUFORT-COASTAL COLLETON-CHARLESTON-COASTAL JASPER-
600 PM EST MON NOV 20 2006

...LAKE WIND ADVISORY FOR LAKE MOULTRIE BEGINNING TONIGHT...
...WIND ADVISORY FOR COASTAL SOUTH CAROLINA AND GEORGIA BEGINNING
TUESDAY AFTERNOON...
...GALE WARNING FOR AMZ330-350-352-354...
...STORM WARNING FOR AMZ374...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST SOUTH CAROLINA...
SOUTHEAST GEORGIA AND THE ADJACENT COASTAL WATERS FROM THE SOUTH
SANTEE RIVER SOUTH CAROLINA TO ALTAMAHA SOUND GEORGIA.

.DAY ONE...TONIGHT.
.LAKE WINDS...WINDS WILL INCREASE TONIGHT OVER LAKE MOULTRIE TO 25
KNOTS WITH GUSTS TO 30 KNOTS. THUS...A LAKE WIND ADVISORY HAS BEEN
ISSUED. REFER TO THE LATEST NON-PRECIPITATION STATEMENT FOR MORE
INFORMATION.

.MARINE...A DEVELOPING STORM SYSTEM WILL BRING DANGEROUS MARINE
CONDITIONS TO THE ADJACENT WATERS TONIGHT THROUGH WEDNESDAY. A STORM
WARNING IS IN EFFECT FOR THE OUTER GEORGIA WATERS WITH GALE WARNINGS
FOR ALL NEARSHORE COASTAL WATERS AND THE CHARLESTON HARBOR. REFER TO
THE LATEST COASTAL WATERS FORECAST AND MARINE WEATHER STATEMENT FOR
DETAILS.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY.
.MARINE...GALE WARNINGS WILL BE ONGOING FOR ALL NEARSHORE WATERS AND
CHARLESTON HARBOR TUESDAY WHILE STORM WARNINGS WILL BE ONGOING FOR
THE WATERS 20 TO 60 NM OFF THE GEORGIA COAST. CONDITIONS WILL
IMPROVE OVER THE ENTIRE MARINE AREA WEDNESDAY NIGHT AND THURSDAY.
REFER TO THE LATEST MARINE WEATHER STATEMENT AND COASTAL WATERS
FORECAST FOR ADDITIONAL INFORMATION.

.HIGH SURF/BEACH EROSION/COASTAL FLOODING...SUBSTANTIAL BEACH
EROSION IS POSSIBLE TUESDAY THROUGH WEDNESDAY. THE THREAT FOR
COASTAL FLOODING HAS DIMINISHED DUE TO THE EXPECTED OFFSHORE WINDS.
A BUILDING NORTHEAST SWELL MAY RESULT IN 5-8 FT WAVES IN THE COASTAL
WATERS TUE THROUGH WED. HIGH SURF ADVISORIES MAY BE NEEDED. REFER TO
THE LATEST SPECIAL WEATHER STATEMENT FOR ADDITIONAL INFORMATION.

.LAKE WINDS...WINDS WILL BE AROUND 35 KNOTS WITH GUSTS TO 45 KNOTS
OVER LAKE MOULTRIE TUESDAY AND WEDNESDAY. THUS...A LAKE WIND
ADVISORY HAS BEEN ISSUED. REFER TO THE LATEST NON-PRECIPITATION
STATEMENT FOR MORE INFORMATION.

.WINDS...STRONG WINDS OF 25 TO 35 MPH WITH GUSTS TO 45 MPH ARE
EXPECTED TO DEVELOP ALONG THE COAST TUESDAY AND PERSIST THROUGH AT
LEAST WEDNESDAY. THUS...A WIND ADVISORY HAS BEEN ISSUED FOR ALL OF
COASTAL SOUTHERN SOUTH CAROLINA AND NORTH COASTAL GEORGIA. REFER TO
THE LATEST NON-PRECIPITATION STATEMENT FOR ADDITIONAL INFORMATION.

.HEAVY RAINFALL...THERE IS THE POSSIBILITY OF HEAVY RAINFALL TONIGHT
THROUGH WEDNESDAY NIGHT...ESPECIALLY ACROSS SOUTHERN SOUTH CAROLINA.
REFER TO THE HYDROLOGIC OUTLOOK PRODUCT FOR ADDITIONAL INFORMATION.

.SPOTTER INFORMATION STATEMENT...
SKYWARN SPOTTER ACTIVATION WILL NOT BE REQUIRED TONIGHT.

RJB/JRL