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#43653 (Received by flhurricane at: 4:34 AM 02.Sep.2005) TCDAT4 TROPICAL DEPRESSION FOURTEEN DISCUSSION NUMBER 4 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT FRI SEP 02 2005 TROPICAL DEPRESSION FOURTEEN REMAINS IN A SOUTHEASTERLY SHEAR ENVIRONMENT THIS MORNING...WITH THE LOW-LEVEL CENTER PARTLY EXPOSED AT THE SOUTHEASTERN EDGE OF A RECTANGULAR CONVECTIVE MASS WITH TOPS COLDER THAN -70C. SATELLITE INTENSITY ESTIMATES ARE 30 KT FROM ALL AGENCIES...SO THAT IS THE INITIAL INTENSITY. THE INITIAL MOTION IS 305/9...JUST A TRIFLE TO THE LEFT OF THE PREVIOUS ADVISORY. THERE IS OTHERWISE LITTLE CHANGE IN THE TRACK FORECAST PHILOSOPHY OR THE TRACK FORECAST. THE DEPRESSION IS BETWEEN A MID-LEVEL RIDGE OVER THE EASTERN ATLANTIC AND A DEEP-LAYER TROUGH/WEAKNESS OVER THE WESTERN ATLANTIC...AND THIS PATTERN SHOULD PERSIST THROUGH THE FORECAST PERIOD. THIS SHOULD PRODUCE A INITIAL NORTHWESTWARD MOTION...FOLLOWED BY A GRADUAL TURN TO THE NORTH-NORTHWEST. ALL TRACK GUIDANCE AGREES ON THIS SCENARIO...AND THE OFFICIAL TRACK WILL FOLLOW IT. THE NEW FORECAST TRACK IS JUST A LITTLE LEFT OF THE PREVIOUS TRACK FOR THE FIRST 24 HR...A LITTLE RIGHT OF THE PREVIOUS TRACK BY 120 HR...AND A LITTLE FASTER. THE INTENSITY FORECAST REMAINS SOMEWHAT PROBLEMATIC. LARGE-SCALE MODELS SUGGEST THE DEPRESSION WILL REMAIN IN SOUTHEASTERLY TO SOUTHERLY SHEAR. SEVERAL MODELS...INCLUDING THE GFDL...DISSIPATE THE SYSTEM BEFORE 120 HR. ON THE OTHER HAND...THE SHIPS MODEL CALLS FOR THE DEPRESSION TO BECOME A HURRICANE IN 84 HR...AND THE ECMWF HOLDS ON TO IT THROUGH 120 HR. THE INTENSITY FORECAST WILL COMPROMISE BETWEEN THESE EXTREMES... CALLING FOR GRADUAL STRENGTHENING THROUGH THE FORECAST PERIOD. IT SHOULD BE NOTED THAT WHILE THE DEPRESSION IS NOT FORECAST TO BECOME A TROPICAL STORM FOR 24 HR...ANY PERSISTENT BURST CONVECTION COULD CAUSE IT TO BECOME A STORM AT JUST ABOUT ANY TIME IN THE NEXT 24 HR. FORECASTER BEVEN FORECAST POSITIONS AND MAX WINDS INITIAL 02/0900Z 20.6N 48.1W 30 KT 12HR VT 02/1800Z 21.6N 49.3W 30 KT 24HR VT 03/0600Z 23.2N 50.9W 35 KT 36HR VT 03/1800Z 25.0N 52.5W 40 KT 48HR VT 04/0600Z 26.8N 53.7W 40 KT 72HR VT 05/0600Z 29.5N 55.0W 45 KT 96HR VT 06/0600Z 32.0N 56.0W 50 KT 120HR VT 07/0600Z 34.5N 56.5W 50 KT |