Hurricane BERTHA

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HURRICANE BERTHA DISCUSSION NUMBER  27
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022008
500 PM EDT WED JUL 09 2008
 
BERTHA'S SATELLITE PRESENTATION HAS DRAMATICALLY IMPROVED DURING THE
LAST 6 HOURS.  THE CYCLONE NOW HAS A DISTINCTIVE EYE AND IS
SURROUNDED BY A SYMMETRIC RING OF COLD CLOUD TOPS.  THE INITIAL
INTENSITY IS RAISED TO 90 KT BASED ON A BLEND OF THE SATELLITE
CLASSIFICATIONS FROM SAB AND TAFB.  BERTHA IS FORECAST TO BE IN A
SEEMINGLY FAVORABLE ENVIRONMENT FOR THE NEXT DAY OR SO AND
CONTINUED STRENGTHENING IS EXPECTED IN THE SHORT-TERM.  BEYOND 36
HOURS...VERTICAL SHEAR IS STILL EXPECTED TO GRADUALLY INCREASE AND
SSTS SLOWLY FALL.  THIS ENVIRONMENT IS EXPECTED TO RESULT IN A SLOW
WEAKENING TREND THROUGH THE END OF THE FORECAST PERIOD.  IT SHOULD
BE NOTED THAT BERTHA COULD BECOME A LITTLE STRONGER THAN CURRENTLY
FORECAST IN THE FIRST 24 HOURS. 
 
BERTHA HAS RECENTLY WOBBLED A LITTLE RIGHT OF THE PREVIOUS MOTION
ESTIMATE BUT THE 12 HOUR AVERAGE MOTION IS ESSENTIALLY
UNCHANGED...305/10.  THE TRACK FORECAST PHILOSOPHY IS THE SAME AS
IN THE PREVIOUS ADVISORY.  A MID-TROPOSPHERIC ANTICYCLONE
CURRENTLY OVER THE WESTERN ATLANTIC IS FORECAST TO MOVE
NORTHEASTWARD WHILE A SHORTWAVE TROUGH MOVES OFF OF THE U.S. EAST
COAST.  THIS SHOULD RESULT IN BERTHA MAKING A GRADUAL TURN TOWARD
THE NORTH DURING THE NEXT 2-3 DAYS.  HOWEVER...THIS TROUGH IS
FORECAST TO BYPASS BERTHA TO THE NORTH AND LEAVE IT BEHIND IN
RELATIVELY WEAK STEERING CURRENTS.  ACCORDINGLY...THE OFFICIAL
FORECAST SHOWS A SLOW NORTHWARD MOTION AT DAYS 3 AND 4.  A SECOND
TROUGH MOVING OFF THE UNITED STATES EAST COAST ON DAY 5 COULD
RESULT IN SOME NORTHWARD ACCELERATION LATE IN THE FORECAST PERIOD. 
IN GENERAL...TRACK MODELS HAVE CHANGED LITTLE SINCE THE LAST
ADVISORY...AND THE NEW OFFICIAL TRACK FORECAST IS ESSENTIALLY AN
UPDATE OF THE PREVIOUS ONE.
 
IT IS STILL TOO EARLY TO KNOW WHETHER BERTHA WILL HAVE AN IMPACT ON
BERMUDA.  INTERESTS ON THAT ISLAND SHOULD CONTINUE TO MONITOR THE
PROGRESS OF THIS HURRICANE OVER THE NEXT COUPLE OF DAYS.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      09/2100Z 24.8N  58.1W    90 KT
 12HR VT     10/0600Z 25.6N  59.2W   100 KT
 24HR VT     10/1800Z 26.8N  60.2W   100 KT
 36HR VT     11/0600Z 28.0N  61.0W   100 KT
 48HR VT     11/1800Z 29.1N  61.3W    95 KT
 72HR VT     12/1800Z 31.0N  61.5W    85 KT
 96HR VT     13/1800Z 32.5N  61.0W    80 KT
120HR VT     14/1800Z 35.5N  60.0W    75 KT
 
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FORECASTER RHOME
 
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