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| #7296 (Received by flhurricane at: 4:52 PM 03.Sep.2004) TCDAT4 TROPICAL STORM IVAN DISCUSSION NUMBER 5 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 PM EDT FRI SEP 03 2004 METEOSAT-8 VISIBLE IMAGERY DEPICTS A WELL-DEFINED CURVED BAND WRAPPING ABOUT TWO-THIRDS AROUND THE SYSTEM CENTER. DVORAK T NUMBERS ARE 3.0 FROM BOTH TAFB AND SAB...AND THE INITIAL INTENSITY IS 45 KT BASED ON THESE ESTIMATES. UPPER LEVEL OUTFLOW IS WELL-DEFINED AND EXPANDING IN ALL QUADRANTS...INDICATIVE OF WEAK VERTICAL SHEAR. THE ENVIRONMENT APPEARS FAVORABLE FOR GRADUAL INTENSIFICATION THROUGHOUT THE FORECAST PERIOD. THE OFFICIAL FORECAST CLOSELY FOLLOWS THE SHIPS GUIDANCE AND BRINGS IVAN TO HURRICANE INTENSITY IN 36 HOURS AND TO 100 KNOTS BY 120 HOURS...WHICH IS LESS AGGRESSIVE THAN THE GFDL. IVAN IS MOVING A LITTLE MORE SOUTH OF DUE WEST...NOW 255/17. THE TROPICAL STORM IS EMBEDDED WITHIN A DEEP EASTERLY CURRENT SOUTH OF A STRONG RIDGE. THIS RIDGE IS FORECAST TO MOVE OR BUILD WESTWARD ALONG WITH IVAN FOR THE NEXT 72 HOURS OR SO...THEREFORE A GENERAL WESTWARD AND EVENTUALLY WEST-NORTHWESTWARD MOTION IS EXPECTED FOR THE NEXT SEVERAL DAYS. THE NOGAPS AND GFDN TURN IVAN TO THE NORTHWEST WELL EAST OF THE LESSER ANTILLES...BUT THIS SCENARIO SEEMS LESS LIKELY GIVEN THE INITIAL MOTION. THE OFFICIAL FORECAST IS IN BEST AGREEMENT WITH THE GFS AND GFDL MODELS...ON THE SOUTHERN SIDE OF THE GUIDANCE SUITE. FORECASTER KNABB/PASCH FORECAST POSITIONS AND MAX WINDS INITIAL 03/2100Z 8.9N 34.6W 45 KT 12HR VT 04/0600Z 8.7N 37.1W 55 KT 24HR VT 04/1800Z 8.7N 40.3W 60 KT 36HR VT 05/0600Z 9.0N 43.4W 65 KT 48HR VT 05/1800Z 9.8N 46.6W 75 KT 72HR VT 06/1800Z 11.5N 53.0W 90 KT 96HR VT 07/1800Z 13.0N 59.0W 95 KT 120HR VT 08/1800Z 15.0N 64.5W 100 KT |
