Hurricane BERTHA

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HURRICANE BERTHA DISCUSSION NUMBER  26
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022008
1100 AM EDT WED JUL 09 2008
 
BERTHA'S CLOUD PATTERN HAS IMPROVED THIS MORNING AND THE EYE APPEARS
TO BE REFORMING. THE INITIAL INTENSITY REMAINS 65 KT BASED ON 1200Z
DVORAK CLASSIFICATIONS BUT BERTHA LOOKS TO BE IN THE PROCESS OF
STRENGTHENING. THE INTENSITY FORECAST CONTINUES TO BE CHALLENGING.
IN THE SHORT-TERM...THE ATMOSPHERE APPEARS FAVORABLE FOR
STRENGTHENING AND THE OCEAN IS PLENTY WARM. HOWEVER...THE VARIOUS
INTENSITY MODELS ARE NOT IN GOOD AGREEMENT ON HOW MUCH OR EVEN WHEN
REINTENSIFICATION MIGHT OCCUR. GIVEN THE CURRENT TREND IN THE
SATELLITE PRESENTATION...THE OFFICIAL FORECAST ASSUMES SOONER
RATHER THAN LATER AND SHOWS BERTHA STRENGTHENING DURING THE FIRST
24 HOURS. THEREAFTER...BERTHA WILL BE MOVING OVER WARMER WATERS BUT
WITH INCREASING VERTICAL SHEAR MAKING IT UNCLEAR WHETHER
INTENSIFICATION WILL CONTINUE. GIVEN THE UNCERTAINTY...THE OFFICIAL
FORECAST CONTINUES THE PREVIOUSLY SHOWN TREND OF SLOW WEAKENING. AS
THE ABOVE SHOWS...THERE IS CONSIDERABLE UNCERTAINTY IN THE
INTENSITY FORECAST.
 
THE INITIAL MOTION IS ESSENTIALLY UNCHANGED FROM THE PREVIOUS
PACKAGE...300/10.  BERTHA SHOULD CONTINUE A SLOW TURN NORTHWARD
DURING THE NEXT 2-3 DAYS AS A MID-TROPOSPHERIC ANTICYCLONE
CURRENTLY NEAR BERMUDA IS FORECAST TO WEAKEN AND A 500 MB
SHORTWAVE TROUGH MOVES OFF OF THE U.S. EAST COAST.  BEYOND 72
HOURS...THE TRACK BECOMES A LITTLE LESS CERTAIN AS THE SHORTWAVE IS
NOT CURRENTLY FORECAST TO PICK UP THE CYCLONE.  RATHER...IT LEAVES
BERTHA BEHIND IN WEAK STEERING CURRENTS POSSIBLY RESULTING IN SLOW
AND ERRATIC MOTION AT THE END OF THE FORECAST.  TRACK MODELS HAVE
NOT DEMONSTRATED GOOD RUN TO RUN CONSISTENCY.  AS A RESULT...THE
NEW OFFICIAL TRACK FORECAST IS ESSENTIALLY UNCHANGED AND LIES WEST
OF THE DYNAMICAL MODEL CONSENSUS.
 
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      09/1500Z 24.2N  57.5W    65 KT
 12HR VT     10/0000Z 24.7N  58.5W    70 KT
 24HR VT     10/1200Z 25.9N  59.7W    75 KT
 36HR VT     11/0000Z 27.2N  60.6W    75 KT
 48HR VT     11/1200Z 28.3N  61.1W    70 KT
 72HR VT     12/1200Z 30.0N  61.5W    70 KT
 96HR VT     13/1200Z 31.5N  61.5W    65 KT
120HR VT     14/1200Z 33.5N  60.5W    60 KT
 
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FORECASTER RHOME
 
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