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| #373137 (Received by flhurricane at: 10:41 AM 02.Sep.2010) TCDAT3 TROPICAL STORM FIONA DISCUSSION NUMBER 12 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL082010 1100 AM AST THU SEP 02 2010 BURSTS OF CONVECTION CONTINUE TO FORM NEAR THE WELL-DEFINED CIRCULATION OF FIONA THIS MORNING. HOWEVER THIS CONVECTION HAS HAD TROUBLE MAINTAINING ITSELF...PROBABLY DUE TO PERSISTENT NORTHERLY SHEAR. DVORAK CLASSIFICATIONS ARE UNCHANGED FROM EARLIER...SO THE INITIAL INTENSITY WILL STAY 45 KT. FIONA HAS TURNED TO THE RIGHT AND IS NOW MOVING 330/15. AS THE CYCLONE ROUNDS THE SOUTHWESTERN PERIPHERY OF A RIDGE OVER THE CENTRAL ATLANTIC...IT IS EXPECTED TO TURN TOWARD THE NORTH AND NORTHEAST BY LATE TOMORROW. MOST OF THE MODEL GUIDANCE IS CLUSTERED ON A TRACK NEAR OR WEST OF BERMUDA IN ABOUT 36-48 HRS...THOUGH WITH SOME SPEED DIFFERENCES. SINCE FIONA HAS SHOWN NO SIGNS OF SLOWING DOWN...AND WILL LIKELY REMAIN A WEAK SYSTEM STEERED BY SWIFT LOW-LEVEL WINDS...THE NHC FORECAST WILL STAY FASTER THAN THE MODEL CONSENSUS. THE NEW FORECAST IS ALSO SHIFTED A LITTLE TO THE RIGHT OF THE PREVIOUS ONE TO COME INTO BETTER AGREEMENT WITH THE LATEST GUIDANCE. THE GFDL SOLUTION OF A SLOWER...MORE WESTWARD TRACK WELL TO THE SOUTHWEST OF BERMUDA IS CONSIDERED UNLIKELY. THE STORM IS WALKING A TIGHTROPE BETWEEN RATHER STRONG NORTHERLY SHEAR TO ITS EAST AND AN AREA OF LIGHTER SHEAR FARTHER WEST. WITH THE RIGHTWARD SHIFT OF THE GUIDANCE THIS MORNING...THIS COULD CAUSE EVEN STRONGER SHEAR IN A DAY OR SO NEAR THE CYCLONE. ALL THE GUIDANCE SHOWS A CONSIDERABLE WEAKENING OF FIONA...EXCEPT FOR THE GFDL WHICH HAS AN UNREALISTIC TRACK FORECAST. THE NHC INTENSITY FORECAST IS REDUCED FROM THE PREVIOUS ONE...BUT IS STILL HIGHER THAN NEARLY ALL OF THE GUIDANCE. FORECAST POSITIONS AND MAX WINDS INITIAL 02/1500Z 24.4N 65.8W 45 KT 12HR VT 03/0000Z 26.4N 66.5W 45 KT 24HR VT 03/1200Z 28.9N 66.7W 45 KT 36HR VT 04/0000Z 31.3N 65.7W 40 KT 48HR VT 04/1200Z 33.8N 64.1W 35 KT 72HR VT 05/1200Z 37.9N 61.4W 25 KT...DISSIPATING 96HR VT 06/1200Z...DISSIPATED $$ FORECASTER BLAKE/PASCH |
