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#372737 (Received by flhurricane at: 4:53 PM 31.Aug.2010) TCDAT3 TROPICAL STORM FIONA DISCUSSION NUMBER 5 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL082010 500 PM AST TUE AUG 31 2010 THUNDERSTORM ACTIVITY HAS RECENTLY DEVELOPED NEAR THE CENTER OF FIONA...HOWEVER THE CONVECTION SHOWS LITTLE BANDING. THE AIRCRAFT FOUND PEAK 925 MB FLIGHT-LEVEL WINDS OF 41 KT AND SEVERAL UNFLAGGED SFMR WINDS OF AROUND 35 KT TO THE NORTH OF THE CENTER. BASED ON THESE DATA...THE INITIAL INTENSITY REMAINS 35 KT. AN UPPER-LEVEL ANTICYCLONE TO THE NORTHWEST OF FIONA IS FORECAST TO PRODUCE INCREASING UPPER-LEVEL NORTHEASTERLY SHEAR OVER THE CYCLONE. THE SHEAR IS EXPECTED TO REMAIN STRONG DURING THE NEXT SEVERAL DAYS AND ONLY A LITTLE STRENGTHENING IS SHOWN IN THE OFFICIAL FORECAST. THE INITIAL MOTION ESTIMATE IS 290/21 KT. FIONA IS FORECAST TO TURN NORTHWESTWARD AND DECELERATE VERY SOON AS IT APPROACHES THE WESTERN EDGE OF THE SUBTROPICAL RIDGE. IN 36-48 HOURS...THE CYCLONE SHOULD TURN NORTHWARD BETWEEN THE RIDGE AND HURRICANE EARL TO THE NORTHWEST. ALL OF GLOBAL MODELS DISSIPATE THE STORM IN 2-3 DAYS AS THE SMALLER CIRCULATION OF FIONA BECOMES AN OPEN TROUGH IN THE STRONG SOUTHWESTERLY FLOW ON THE SOUTHEASTERN SIDE OF EARL. THE OFFICIAL FORECAST FOLLOWS THIS SCENARIO...HOWEVER DISSIPATION COULD OCCUR EARLIER THAN SHOWN BELOW. FORECAST POSITIONS AND MAX WINDS INITIAL 31/2100Z 16.7N 57.7W 35 KT 12HR VT 01/0600Z 17.9N 60.8W 40 KT 24HR VT 01/1800Z 20.2N 63.7W 40 KT 36HR VT 02/0600Z 23.0N 66.0W 40 KT 48HR VT 02/1800Z 26.5N 67.7W 35 KT 72HR VT 03/1800Z 33.5N 67.5W 35 KT 96HR VT 04/1800Z...DISSIPATED $$ FORECASTER BROWN |