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#4111 (Received by flhurricane at: 4:56 AM 10.Aug.2004) TCDAT3 TROPICAL STORM CHARLEY DISCUSSION NUMBER 4 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT TUE AUG 10 2004 THE DEEP CONVECTION THAT FORMED NEAR THE CENTER OVERNIGHT HAS PERSISTED DURING THE PAST FEW HOURS AS THE CYCLONE APPEARS TO BE GETTING BETTER ORGANIZED. WHILE OUTER BANDS OF DEEP CONVECTION ARE CURRENTLY MINIMAL BUT INCREASING...THE CIRCULATION OCCUPIES A LARGE ENVELOPE AND OUTFLOW IS EXCELLENT IN ALL DIRECTIONS. DVORAK CI NUMBERS ARE A CONSENSUS 2.5...AND ON THIS BASIS THE SYSTEM IS UPGRADED TO TROPICAL STORM CHARLEY WITH AN INTENSITY OF 35 KT. CHARLEY CONTINUES TO SPEED ALONG AT 285/21...SLIGHTLY FASTER THAN PREVIOUSLY...PERHAPS IN PART DUE TO THE INCREASED DEPTH OF THE CONVECTION. MOST TRACK GUIDANCE INDICATES THAT THIS WEST-NORTHWESTWARD MOTION SHOULD CONTINUE FOR ABOUT THE NEXT TWO DAYS...WITH STEERING PROVIDED BY THE SUBTROPICAL RIDGE CENTERED NORTH OF THE GREATER ANTILLES. HOWEVER...THE MODELS DIVERGE THEREAFTER AS CHARLEY REACHES A WEAKNESS IN THE RIDGE CAUSED BY A MID-LATITUDE TROUGH OVER THE EASTERN UNITED STATES. WHILE THE NOGAPS...GFDL...AND UKMET NOW TAKE THE SYSTEM OVER THE YUCATAN PENINSULA...WELL TO THE LEFT OF THE PREVIOUS FORECAST...THE GFS TAKES CHARLEY INTO THE EASTERN GULF OF MEXICO AT DAYS FOUR AND FIVE. GIVEN THE WIDE SPREAD...THE OFFICIAL FORECAST IS NUDGED ONLY SLIGHTLY TO THE LEFT OF THE PREVIOUS FORECAST...AND A LITTLE FASTER GIVEN THE CURRENT MOTION. THE ENVIRONMENT AHEAD OF CHARLEY IS QUITE FAVORABLE...WITH VERY WEAK VERTICAL SHEAR AND AN INCREASINGLY WARM OCEAN. THE GFDL MAKES CHARLEY A HURRICANE WITHIN THREE DAYS...AND SHIPS DOES SO IN LESS THAN TWO DAYS. THE OFFICIAL FORECAST IS CLOSER TO THE GFDL INTENSITY GUIDANCE...BUT INDICATES MORE INTENSIFICATION THAN THE PREVIOUS ADVISORY DUE TO THE IMPROVING ORGANIZATION OF THE SYSTEM. FORECASTER KNABB/FRANKLIN FORECAST POSITIONS AND MAX WINDS INITIAL 10/0900Z 13.0N 66.3W 35 KT 12HR VT 10/1800Z 13.9N 69.3W 40 KT 24HR VT 11/0600Z 15.0N 72.9W 45 KT 36HR VT 11/1800Z 16.3N 76.2W 50 KT 48HR VT 12/0600Z 17.5N 79.0W 55 KT 72HR VT 13/0600Z 19.5N 82.5W 65 KT 96HR VT 14/0600Z 22.5N 86.0W 75 KT 120HR VT 15/0600Z 26.0N 88.0W 80 KT |