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| #199831 (Received by flhurricane at: 4:37 AM 08.Jul.2008) TCDAT2 HURRICANE BERTHA DISCUSSION NUMBER 21 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022008 500 AM EDT TUE JUL 08 2008 THE EYE OF THE HURRICANE HAS BECOME A LITTLE LESS DISTINCT OVER THE PAST SEVERAL HOURS. NONETHELESS...BERTHA HAS BEEN MAINTAINING A FAIRLY SYMMETRICAL RING OF COLD CLOUD TOPS AROUND THE CENTER. SUBJECTIVE AND OBJECTIVE DVORAK T-NUMBERS HAVE COME DOWN SLIGHTLY BUT CURRENT INTENSITY ESTIMATES...BOTH OBJECTIVE AND SUBJECTIVE... REMAIN CLOSE TO 105 KT. HENCE THE ADVISORY INTENSITY IS UNCHANGED. SOME FLUCTUATIONS IN STRENGTH ASSOCIATED WITH EYEWALL REPLACEMENTS COULD OCCUR WITHIN THE NEXT 12 HOURS OR SO. IN THE LONGER-TERM... THE ENVIRONMENT IS EXPECTED TO GRADUALLY BECOME LESS CONDUCIVE FOR STRENGTHENING AS BERTHA MOVES TOWARDS HIGHER LATITUDES. THIS IS REFLECTED IN THE SHIPS MODEL...WHICH WEAKENS BERTHA TO MINIMAL HURRICANE STRENGTH BY 72 HOURS. THE OFFICIAL INTENSITY FORECAST CLOSELY FOLLOWS THE INTENSITY MODEL CONSENSUS ICON. EYE FIXES GIVE A MOTION ESTIMATE OF 310/9 WHICH IS SLIGHTLY TO THE RIGHT OF PREVIOUS ESTIMATES. GLOBAL MODELS ARE NOW IN FAIRLY GOOD AGREEMENT THAT BERTHA WILL HEAD FOR A WEAKNESS IN THE MID-TROPOSPHERIC SUBTROPICAL RIDGE AND TURN NORTHWARD LATER IN THE FORECAST PERIOD. IT SHOULD BE NOTED THAT THE GFDL AND HWRF MODELS HAVE BEEN CALLING FOR THIS SCENARIO MORE CONSISTENTLY THAN THE OTHER GUIDANCE OVER THE PAST COUPLE OF DAYS. THE OFFICIAL TRACK FORECAST IS ADJUSTED EAST OF THE PREVIOUS ONE BUT IS STILL TO THE WEST OF MOST OF THE DYNAMICAL MODEL TRACKS AS WELL AS THE MODEL CONSENSUS. BY DAY 5...STEERING CURRENTS COULD BECOME QUITE WEAK AND BERTHA MAY MOVE SLOWLY AND ERRATICALLY AS IT WAITS TO BE EVENTUALLY PICKED UP BY A TROUGH IN THE WESTERLIES. FORECAST POSITIONS AND MAX WINDS INITIAL 08/0900Z 21.4N 53.3W 105 KT 12HR VT 08/1800Z 22.2N 54.4W 100 KT 24HR VT 09/0600Z 23.4N 55.9W 95 KT 36HR VT 09/1800Z 24.7N 57.4W 90 KT 48HR VT 10/0600Z 26.0N 58.6W 85 KT 72HR VT 11/0600Z 28.0N 59.5W 80 KT 96HR VT 12/0600Z 30.0N 59.5W 75 KT 120HR VT 13/0600Z 32.0N 59.0W 70 KT $$ FORECASTER PASCH |
