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| #199869 (Received by flhurricane at: 10:55 AM 08.Jul.2008) TCDAT2 HURRICANE BERTHA DISCUSSION NUMBER 22 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022008 1100 AM EDT TUE JUL 08 2008 CONVENTIONAL AND MICROWAVE IMAGERY SHOW A RAPID DEGRADATION OF BERTHA'S STRUCTURE DURING THE LAST 6 HOURS. THE EYE HAS DISAPPEARED AND CLOUD TOPS HAVE WARMED CONSIDERABLY. THERE IS ALSO EVIDENCE IN MICROWAVE IMAGERY THAT THE WESTERN PORTION OF THE EYEWALL HAS ERODED. A BLEND OF THE FINAL T AND CI NUMBERS FROM THE DVORAK TECHNIQUE SUPPORTS AN INITIAL INTENSITY OF 90 KT AND LATEST OBJECTIVE T NUMBERS SUGGEST AN EVEN LOWER INTENSITY. THE INITIAL INTENSITY IS CONSERVATIVELY SET AT 90 KT. IT WOULD APPEAR THAT BERTHA HAS FINALLY ENCOUNTERED THE HIGHER SHEAR ENVIRONMENT WE'VE BEEN FORECASTING. ADDITIONALLY...THE CYCLONE IS MOVING OVER SLIGHTLY COOLER WATERS AND THERE ARE SOME INDICATIONS IN SATELLITE IMAGERY THAT IT COULD BE ENTRAINING DRY AIR. BOTTOM LINE...THE ENVIRONMENT LOOKS RATHER HOSTILE AND BERTHA SHOULD CONTINUE TO WEAKEN IN THE SHORT-TERM. TOWARDS THE END OF THE FORECAST PERIOD...THE SHEAR COULD RELAX AND SSTS INCREASE SO THERE IS SOME POTENTIAL FOR A LITTLE RE-INTENSIFICATION. HOWEVER...GIVEN THE UNCERTAINTY IN INTENSITY FORECASTING...THE OFFICIAL FORECAST MERELY SHOWS SLOW WEAKENING THROUGH THE FORECAST PERIOD AND IS IN GOOD AGREEMENT WITH A CONSENSUS OF THE VARIOUS INTENSITY MODELS. BERTHA HAS BEEN MOVING A LITTLE TO THE RIGHT OF THE PREVIOUS ESTIMATE OR 315/9. 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. SINCE THE STEERING CURRENTS COULD BECOME RATHER WEAK AS A RESULT OF THIS EVOLUTION...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 FORECAST SO ONLY COSMETIC CHANGES TO THE OFFICIAL TRACK FORECAST ARE NEEDED AT THIS TIME. FORECAST POSITIONS AND MAX WINDS INITIAL 08/1500Z 22.1N 53.8W 90 KT 12HR VT 09/0000Z 23.1N 54.9W 85 KT 24HR VT 09/1200Z 24.3N 56.4W 80 KT 36HR VT 10/0000Z 25.5N 57.8W 80 KT 48HR VT 10/1200Z 26.6N 58.7W 75 KT 72HR VT 11/1200Z 28.5N 59.5W 70 KT 96HR VT 12/1200Z 30.5N 59.5W 65 KT 120HR VT 13/1200Z 32.5N 58.5W 65 KT $$ FORECASTER RHOME |
