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#4169 (Received by flhurricane at: 9:36 PM 10.Aug.2004) TCDAT2 TROPICAL STORM BONNIE DISCUSSION NUMBER 12 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 PM EDT TUE AUG 10 2004 AN AIRCRAFT RECONNAISSANCE MISSION FROM 17 TO 23Z FOUND A MAXIMUM WIND OF 43 KT AT 850-MB FLIGHT LEVEL AND 1004 MB. ALSO SATELLITE IMAGERY SHOWS A SPUTTERING VERY SMALL AREA OF DEEP CONVECTION. THEREFORE THE MAXIMUM SURFACE WIND IS REDUCED FROM 45 KT TO 40 KT. THE INITIAL MOTION ESTIMATE IS 010/04. THE TRACK GUIDANCE REMAINS IN GOOD AGREEMENT ABOUT AN ACCELERATION TOWARD THE NORTHEAST IN ADVANCE OF A MID LATITUDE TROUGH DIGGING SOUTHWARD INTO THE NORTHERN GULF OF MEXICO. THE OFFICIAL FORECAST TRACK IS SHIFTED A LITTLE TO THE LEFT OF THE PREVIOUS ADVISORY FOLLOWING A CONSENSUS OF THE GLOBAL TRACK GUIDANCE MODELS. BONNIE ONLY HAS ABOUT 24 HOURS TO INTENSIFY BEFORE ENCOUNTERING STRONG SOUTHWESTERLY VERTICAL WIND SHEAR. SINCE THE CURRENT TREND HAS BEEN FOR SLIGHT WEAKENING...SIGNIFICANT INTENSIFICATION IS GETTING LESS LIKELY. THE GFDL MODEL BRINGS THE WINDS TO 82 KT BEFORE LANDFALL...BUT NONE OF THE OTHER GUIDANCE SHOWS MUCH STRENGTHENING. THE SHIPS MODEL GOES TO ONLY 45 KT BEFORE LANDFALL. THE PREVIOUS ADVISORY FORECAST 70 KT BEFORE LANDFALL AND THIS ADVISORY FORECAST BACKS OFF TO 60 KT WHICH IS PROBABLY STILL TOO HIGH. THE TRACK AND INTENSITY FORECASTS REQUIRE A TROPICAL STORM WATCH FOR THE FLORIDA PANHANDLE. FORECASTER LAWRENCE FORECAST POSITIONS AND MAX WINDS INITIAL 11/0300Z 25.0N 90.4W 40 KT 12HR VT 11/1200Z 26.0N 90.1W 50 KT 24HR VT 12/0000Z 27.6N 89.0W 60 KT 36HR VT 12/1200Z 29.8N 86.7W 60 KT 48HR VT 13/0000Z 32.5N 83.2W 30 KT...INLAND 72HR VT 14/0000Z 42.0N 75.0W 30 KT...EXTRATROPICAL 96HR VT 15/0000Z...ABSORBED BY FRONTAL SYSTEM |