Hurricane BERTHA

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HURRICANE BERTHA DISCUSSION NUMBER  23
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022008
500 PM EDT TUE JUL 08 2008
 
BERTHA'S SATELLITE PRESENTATION CONTINUES TO DEGRADE THIS AFTERNOON
AND DVORAK DATA T-NUMBERS HAVE FALLEN DURING THE LAST 6 HOURS. THE
INITIAL INTENSITY IS LOWERED TO 75 KT BASED ON AN AVERAGE OF THE
VARIOUS INTENSITY ESTIMATES. INDEED...BERTHA'S RAPID
INTENSIFICATION YESTERDAY HAS BEEN EQUALED BY ITS RAPID WEAKENING
TODAY. SUCH INTENSITY FLUCTUATIONS REMAIN A FORECASTING CHALLENGE
AND SERVE AS AN IMPORTANT REMINDER FOR THE UNCERTAINTIES ASSOCIATED
WITH INTENSITY FORECASTS. GIVEN THE CURRENT TREND IN SATELLITE
IMAGERY...CONTINUED WEAKENING IS POSSIBLE IN THE SHORT-TERM. MOST
OF THE INTENSITY MODELS SUGGEST THAT BERTHA MIGHT EVEN REGAIN SOME
STRENGTH LATER IN THE FORECAST AS THE SHEAR RELAXES AND THE SSTS
INCREASE. DUE TO THE UNCERTAINTY...THE OFFICIAL FORECAST SHOWS
SLIGHT WEAKENING IN THE SHORT-TERM WITH LITTLE CHANGE THEREAFTER.

BERTHA CONTINUES MOVING NORTHWESTWARD WITH AN INITIAL MOTION
ESTIMATE OF 310/10. BERTHA SHOULD CONTINUE TO GRADUALLY TURN
NORTHWARD OVER THE NEXT COUPLE OF DAYS AS A MID-LEVEL RIDGE OVER
THE WESTERN ATLANTIC WEAKENS AND IS REPLACED BY A WEAK TROUGH. THIS
EVOLUTION OF THE LARGE-SCALE PATTERN COULD RESULT IN THE STEERING
CURRENTS BECOMING RATHER WEAK BEYOND 72 HOURS...AND BERTHA COULD
MOVE SLOWLY AND ERRATICALLY TOWARDS THE END OF THE FORECAST. IT IS
FOR THIS REASON THAT INTERESTS IN BERMUDA SHOULD CONTINUE TO
MONITOR THE PROGRESS OF THIS SYSTEM. TRACK MODELS HAVE NOT CHANGED
SIGNIFICANTLY SINCE THE LAST ADVISORY AND NEITHER HAS THE OFFICIAL
FORECAST.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      08/2100Z 22.7N  54.8W    75 KT
 12HR VT     09/0600Z 23.6N  56.0W    70 KT
 24HR VT     09/1800Z 24.8N  57.4W    65 KT
 36HR VT     10/0600Z 26.0N  58.5W    65 KT
 48HR VT     10/1800Z 27.0N  59.2W    65 KT
 72HR VT     11/1800Z 29.0N  60.0W    60 KT
 96HR VT     12/1800Z 31.0N  59.5W    60 KT
120HR VT     13/1800Z 33.0N  58.5W    60 KT
 
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FORECASTER RHOME
 
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