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| #372795 (Received by flhurricane at: 10:41 PM 31.Aug.2010) TCDAT3 TROPICAL STORM FIONA DISCUSSION NUMBER 6 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL082010 1100 PM AST TUE AUG 31 2010 THE METEO FRANCE GUADELOUPE-MARTINIQUE RADAR MOSAIC WAS VERY HELPFUL IN IDENTIFYING THE CIRCULATION CENTER OF FIONA. DEEP CONVECTION HAS BEEN PERSISTENT NEAR THE CENTER...BUT THE CLOUD PATTERN IS A RATHER SHAPELESS BLOB...AND APPEARS TO BE ELONGATED ALONG AN AXIS SOUTHEAST TO NORTHWEST. THE DVORAK INTENSITY ESTIMATES REMAIN AT 30 KT FROM BOTH TAFB AND SAB...BUT THE INITIAL INTENSITY WILL REMAIN AT 35 KT BASED ON THE PERSISTENT DEEP CONVECTION TO THE NORTH OF THE CENTER WHERE THE EARLIER AIRCRAFT RECONNAISSANCE RECORDED FLIGHT-LEVEL WINDS OF 41 KT. NORTHEASTERLY SHEAR ASSOCIATED WITH THE SOUTHEAST OUTFLOW CHANNEL OF EARL IS EXPECTED TO IMPINGE ON THE WESTERN PORTION OF THE CYCLONE IN 36 HOURS. THE SHIPS MODEL AS WELL AS THE GLOBAL MODELS ALL SUGGEST THAT THE SHEAR WILL SIGNIFICANTLY INCREASE OVER THE CYCLONE THROUGH DAY 3... CAUSING DISSIPATION BY DAY 4. THERE IS SOMEWHAT OF A CHANCE... HOWEVER...OF MINIMAL STRENGTHENING PRIOR TO THE INCREASING SHEAR DURING THE EARLY PORTION OF THE FORECAST. THE INITIAL MOTION IS SIMILAR TO THE PREVIOUS ADVISORY ESTIMATE...BUT A LITTLE SLOWER...290/17 KT. LARGE-SCALE MODELS INDICATE THAT FIONA WILL TURN NORTHWESTWARD ALONG THE SOUTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE DURING THE NEXT 24 HOURS. THROUGH THE REMAINING FORECAST PERIOD...THE CYCLONE SHOULD TURN NORTHWARD WITHIN A STIFF SOUTHERLY FLOW BETWEEN THE RIDGE EXTENDING OVER BERMUDA AND HURRICANE EARL TO THE NORTHWEST. THE OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS PACKAGE...WITH ONLY A SLIGHT ADJUSTMENT TO THE LEFT...AND IS BASED ON THE MULTI-MODEL TVCN CONSENSUS. FORECAST POSITIONS AND MAX WINDS INITIAL 01/0300Z 16.9N 59.4W 35 KT 12HR VT 01/1200Z 18.7N 62.0W 40 KT 24HR VT 02/0000Z 21.2N 64.7W 40 KT 36HR VT 02/1200Z 24.4N 66.5W 40 KT 48HR VT 03/0000Z 27.8N 67.6W 35 KT 72HR VT 04/0000Z 35.0N 66.0W 30 KT 96HR VT 05/0000Z...DISSIPATED $$ FORECASTER ROBERTS/PASCH |
