Tropical Storm Hanna

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Tropical Storm Hanna

• 1100L 05 Sept 2008
• Regis Walter
• NOAA Meteorologist

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Estimated arrival time of TS force winds Central
SC Coast 1400 EDT today Southern NC Coast
1600 EDT Today Landfall 0300 EDT Saturday,
Sept. 6 36 miles ENE of Charleston, SC or 25
miles S of Georgetown, SC
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Current Satellite Image
Center TS Hanna
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3 Day Total RainfallEnding Monday Morning, Sept.
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7 Inches
6 Inches
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NWS RadarMelbourne, FL
Center TS Hanna
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CENTER OF HANNA OFF THE EAST COAST OF
FLORIDAWARNINGS AND WATCHES EXTENDED NORTHWARD

• AT 1100 AM EDT...1500Z...THE CENTER OF TROPICAL
  STORM HANNA WAS LOCATED NEAR 28.9 NORTH 79.2 WEST
  OR ABOUT 110 MILES EAST OF DAYTONA BEACH FLORIDA
  AND ABOUT 375 MILES SOUTH-SOUTHWEST OF WILMINGTON
  NORTH CAROLINA.
• HANNA IS MOVING TOWARD THE NORTHWEST NEAR 20 MPH.
  A TURN TOWARD THE NORTH IS EXPECTED LATER
  TODAY...WITH A TURN TOWARD THE NORTHEAST AND AN
  INCREASE IN FORWARD SPEED EXPECTED ON SATURDAY.
  ON THE FORECAST TRACK...THE CENTER OF HANNA WILL
  BE NEAR THE SOUTHEAST COAST OF THE UNITED STATES
  THIS AFTERNOON AND TONIGHT.
• MAXIMUM SUSTAINED WINDS ARE NEAR 65 MPH WITH
  HIGHER GUSTS. ONLY SLIGHT STRENGTHENING IS
  FORECAST PRIOR TO LANDFALL... ALTHOUGH IT IS
  STILL POSSIBLE FOR HANNA TO BECOME A HURRICANE.
  WEAKENING IS EXPECTED AFTER LANDFALL.
• TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO
  315 MILES FROM THE CENTER.
• ESTIMATED MINIMUM CENTRAL PRESSURE IS 980
  MB...28.94 INCHES.

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Watches and Warnings

• T 11 AM EDT...1500 UTC...THE TROPICAL STORM
  WARNING FOR THE UNITED STATES EAST COAST IS
  EXTENDED NORTHWARD TO SANDY HOOK NEW
  JERSEY...INCLUDING ALL OF CHESAPEAKE BAY....THE
  TIDAL POTOMAC... WASHINGTON D.C...AND DELAWARE
  BAY.
• A TROPICAL WARNING IS NOW IN EFFECT FROM ALTAMAHA
  SOUND GEORGIA NORTHWARD ALONG THE ATLANTIC COAST
  TO SANDY HOOK NEW JERSEY...INCLUDING PAMLICO AND
  ALBEMARLE SOUNDS...INCLUDING ALL OF CHESAPEAKE
  BAY....THE TIDAL POTOMAC... WASHINGTON D.C...AND
  DELAWARE BAY.
• A TROPICAL STORM WARNING REMAINS IN EFFECT FOR
  THE NORTHWESTERN BAHAMAS.
• THE HURRICANE WATCH REMAINS IN EFFECT FROM NORTH
  OF EDISTO BEACH SOUTH CAROLINA TO CURRITUCK BEACH
  LIGHT NORTH CAROLINA...INCLUDING PAMLICO SOUND.
• AT 1100 AM EDT...1500 UTC...A TROPICAL STORM
  WATCH IS IN EFFECT FROM NORTH OF SANDY HOOK NEW
  JERSEY TO WATCH HILL RHODE ISLAND... INCLUDING
  LONG ISLAND.

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Rainfall and Ocean Swells

• COASTAL STORM SURGE FLOODING OF 4 TO 6 FEET ABOVE
  NORMAL TIDE LEVELS...ALONG WITH LARGE AND
  DANGEROUS BATTERING WAVES...CAN BE EXPECTED NEAR
  AND TO THE EAST OF THE PATH OF THE CENTER OF
  HANNA.
• HANNA IS EXPECTED TO PRODUCE RAINFALL
  ACCUMULATIONS OF 3 TO 7 INCHES FROM COASTAL SOUTH
  CAROLINA...NORTHWARD THROUGH NORTH CAROLINA INTO
  CENTRAL VIRGINA...MARYLAND...AND SOUTHEASTERN
  PENNSYLVANIA. ISOLATED MAXIMUM AMOUNTS OF 10
  INCHES ARE POSSIBLE.
• ADDITIONAL RAINFALL AMOUNTS OF 1 TO 3 INCHES ARE
  POSSIBLE ALONG THE FLORIDA EAST COAST AND COASTAL
  GEORGIA.
• THE POTENTIAL FOR EXTREMELY HEAVY RAINFALL TOTALS
  AND FLASH FLOODING WILL BE SIGNIFICANT FOR THE
  NORTHERN MID-ATLANTIC STATES AND SOUTHERN NEW
  ENGLAND AS HANNA ADVANCES NORTHWARD ON SATURDAY
  AND SUNDAY.
• RAINFALL TOTALS OF 4 TO 8 INCHES WITH LOCALIZED
  HEAVIER AMOUNTS ARE POSSIBLE THERE.
• ISOLATED TORNADOES ARE POSSIBLE TONIGHT OVER THE
  COASTAL AREAS OF SOUTH AND NORTH CAROLINA.

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Technical Discussion

• SATELLITE IMAGERY AND RADAR DATA FROM THE
  MELBOURNE WSR-88D INDICATE THAT HANNA HAS BECOME
  A LITTLE BETTER ORGANIZED THIS MORNING...AS THE
  LATEST CONVECTIVE BURST HAS PRODUCED AN INNER
  WIND CORE. HOWEVER...THE RADAR-OBSERVED
  VELOCITIES DO NOT YET SUGGEST INTENSIFICATION.
  THE INITIAL INTENSITY REMAINS 55 KT.
• THE CENTER OF HANNA JOGGED WESTWARD BETWEEN
  06-12Z. HOWEVER...THE MELBOURNE RADAR SUGGEST THE
  CENTER HAS RESUMED A MORE NORTHWARD
  MOTIONS...WITH THE INITIAL MOTION ESTIMATED AT
  325/17. HANNA IS MOVING AROUND THE WESTERN END OF
  THE SUBTROPICAL RIDGE OVER THE WESTERN ATLANTIC
  AND SHOULD ENTER THE WESTERLIES IN 24-48 HR. THIS
  SHOULD RESULT IN RECURVATURE TO THE NORTHEAST AND
  ACCELERATION.
• ALL GUIDANCE AGREES WITH THIS SCENARIO...AND
  THERE ARE NO SIGNIFICANT OUTLIERS AMONGST THE
  DYNAMICAL MODELS. THE NEW FORECAST TRACK IS
  ADJUSTED A LITTLE TO THE LEFT FOR THE FIRST 36 HR
  TO ACCOUNT FOR THE INITIAL POSITION...AND IS
  CLOSE TO THE PREVIOUS FORECAST TRACK THEREAFTER.

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Technical Discussion Cont.

• WHILE VERTICAL WIND SHEAR AND DRY AIR ENTRAINMENT
  ARE STILL ISSUES...THE INCREASED ORGANIZATION
  SUGGESTS THE POSSIBILITY OF STRENGTHENING BEFORE
  LANDFALL. THUS...THE INTENSITY FORECAST CALLS FOR
  A PEAK INTENSITY OF 60 KT NEAR LANDFALL.
• NONE OF THE GUIDANCE INDICATES THAT HANNA WILL
  REACH HURRICANE STRENGTH PRIOR TO
  LANDFALL...ALTHOUGH THIS CANNOT BE RULED OUT. THE
  CYCLONE SHOULD WEAKEN AFTER LANDFALL AND BECOME
  EXTRATROPICAL IN ABOUT 48 HR.
• THE GFS AND UKMET SUGGEST THE POSSIBILITY OF
  DEEPENING AS AN EXTRATROPICAL SYSTEM LATE IN THE
  PERIOD...AND THIS IS REFLECTED IN THE 96 AND 120
  HR FORECASTS.