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#108971 (Received by flhurricane at: 10:40 PM 05.Sep.2006) TCDAT1 TROPICAL STORM FLORENCE DISCUSSION NUMBER 10 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL062006 1100 PM EDT TUE SEP 05 2006 WHILE THE OVERALL CIRCULATION OF FLORENCE IS VERY LARGE...FINDING THE EXACT CENTER IS SOMEWHAT DIFFICULT. AN AMBIGUITY ANALYSIS FROM THE 2105 UTC QUIKSCAT OVERPASS INDICATED THAT THE CENTER REMAINS BROAD AND ELONGATED NORTHEAST TO SOUTHWEST. THE CENTER THAT WE HAVE BEEN TRACKING APPEARS TO BE LOCATED SOUTHWEST OF THE MAIN AREA OF DEEP CONVECTION. ALTHOUGH THE CONVECTION IS VERY STRONG...THERE ARE NO DISCERNIBLE BANDING FEATURES. DUE TO THE CENTER LOCATION UNCERTAINTIES...THE DVORAK INTENSITY ESTIMATES RANGE FROM 30 KT FROM TAFB...35 KT FROM SAB...AND 45 KT FROM AFWA. THEREFORE....THE INITIAL INTENSITY WILL REMAIN 40 KT FOR THIS ADVISORY. THE INITIAL MOTION ESTIMATE IS 290/10. THE TRACK MODELS CONTINUE TO AGREE ON A GENERAL WEST-NORTHWEST HEADING SOUTH OF A DEEP LAYER RIDGE WHICH EXPANDS EASTWARD OVER THE NEXT FEW DAYS. LATE IN THE FORECAST PERIOD...THE GLOBAL MODELS SUGGEST THAT FLORENCE WILL BE APPROACHING THE SOUTHWESTERN PERIPHERY OF THE HIGH AND BEGIN TURNING NORTHWESTWARD. THE TRACK FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY THROUGH 72 HOURS...BUT WAS ADJUSTED A LITTLE EASTWARD...CLOSER TO THE MODEL CONSENSUS AND FSU SUPERENSEMBLE AT 96 AND 120 HOURS. FLORENCE HAS BEEN UNDER THE INFLUENCE OF SOUTHWESTERLY VERTICAL SHEAR ASSOCIATED WITH AN UPPER-LEVEL TROUGH TO ITS NORTHWEST. WATER VAPOR IMAGERY SUGGESTS THAT THE TROUGH IS BEGINNING TO CUT-OFF AND MOVE WEST-SOUTHWESTWARD...MUCH LIKE THE EVOLUTION PREDICTED BY THE GLOBAL MODELS. AS THIS OCCURS...THE SHEAR IS EXPECTED TO RELAX WITH THE ENVIRONMENT BECOMING QUITE FAVORABLE FOR INTENSIFICATION. THE OFFICIAL FORECAST WILL SHOW STRENGTHENING AND INDICATES THAT FLORENCE COULD BECOME A HURRICANE IN ABOUT 2 DAYS. THIS INTENSITY FORECAST IS ONLY SLIGHTLY BELOW THE AVAILABLE NUMERICAL GUIDANCE. THE FORECAST TROPICAL STORM-FORCE WIND RADII HAVE BEEN EXPANDED USING GUIDANCE FROM THE GLOBAL MODEL PREDICTIONS...WHICH DEPICT A RATHER LARGE CIRCULATION. THESE MODELS HAVE SHOWN SOME SKILL IN FORECASTING THE EVOLUTION OF TROPICAL CYCLONE OUTER WIND FIELDS. FORECAST POSITIONS AND MAX WINDS INITIAL 06/0300Z 17.7N 49.5W 40 KT 12HR VT 06/1200Z 18.3N 51.0W 45 KT 24HR VT 07/0000Z 19.3N 53.0W 55 KT 36HR VT 07/1200Z 20.3N 55.2W 60 KT 48HR VT 08/0000Z 21.3N 57.6W 65 KT 72HR VT 09/0000Z 23.5N 62.5W 75 KT 96HR VT 10/0000Z 25.5N 66.5W 85 KT 120HR VT 11/0000Z 28.5N 69.0W 95 KT $$ FORECASTER BROWN/PASCH |