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#105448 (Received by flhurricane at: 5:03 AM 22.Aug.2006) TCDAT4 TROPICAL DEPRESSION FOUR DISCUSSION NUMBER 3 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL042006 500 AM EDT TUE AUG 22 2006 THE OVERALL CLOUD PATTERN HAS INCREASED SLIGHTLY IN ORGANIZATION OVER THE PAST FEW HOURS AND NEW CONVECTION HAS BEEN DEVELOPING CLOSE TO THE ESTIMATED CENTER. HOWEVER...SATELLITE INTENSITY ESTIMATES REMAIN 30 KT FROM TAFB AND SAB...AND 25 KT FROM AFWA. THEREFORE...THE INITIAL INTENSITY WILL BE HELD AT 30 KT. THE INITIAL MOTION ESTIMATE IS 285/14...SLIGHTLY FASTER THAN BEFORE. GLOBAL MODELS REMAIN IN GOOD AGREEMENT ON A WEST- NORTHWEST TO NORTHWESTWARD MOTION SOUTH OF A MID-TROPOSPHERIC RIDGE THROUGH 48 HOURS. THEREAFTER...THE UKMET MODEL DEPICTS A WEAKER CYCLONE...THAT IS STEERED MORE WESTWARD BY THE LOW- TO MID-LEVEL FLOW. THE GFS AND GFDL DEPICT A STRONGER SYSTEM THAT CONTINUES NORTHWEST INTO A WEAKNESS IN THE RIDGE THAT DEVELOPS OVER THE CENTRAL ATLANTIC. THE OFFICIAL TRACK FORECAST REMAINS A LITTLE LEFT OF THE DYNAMICAL MODELS EARLY IN THE FORECAST PERIOD...BUT IS NEAR THE MIDDLE OF THE MODEL GUIDANCE BEYOND 72 HOURS...AND IS CLOSEST TO THE GFDL AND CONU CONSENSUS. THE DEPRESSION IS FORECAST TO REMAIN IN A FAVORABLE ATMOSPHERIC ENVIRONMENT AND OVER WARM WATER FOR THE NEXT FEW DAYS...SO GRADUAL STRENGTHENING IS ANTICIPATED. THE OFFICIAL INTENSITY FORECAST CLOSELY FOLLOWS THE SHIPS GUIDANCE AND IS UNCHANGED FROM THE PREVIOUS ADVISORY. IF CURRENT TRENDS CONTINUE...THE DEPRESSION COULD BECOME A TROPICAL STORM LATER THIS MORNING. IT SHOULD BE NOTED THAT THE SHIPS MODEL HALTS STRENGTHENING AT DAYS 4 AND 5 DUE TO INCREASING SOUTHERLY SHEAR ASSOCIATED WITH AN UPPER-LEVEL TROUGH OVER THE CENTRAL ATLANTIC. FORECAST POSITIONS AND MAX WINDS INITIAL 22/0900Z 12.8N 24.6W 30 KT 12HR VT 22/1800Z 13.7N 26.6W 35 KT 24HR VT 23/0600Z 15.1N 29.3W 40 KT 36HR VT 23/1800Z 16.7N 32.0W 45 KT 48HR VT 24/0600Z 18.3N 34.8W 50 KT 72HR VT 25/0600Z 21.5N 40.5W 60 KT 96HR VT 26/0600Z 24.5N 46.0W 65 KT 120HR VT 27/0600Z 27.5N 51.5W 65 KT |