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| #7900 (Received by flhurricane at: 4:54 AM 11.Sep.2004) TCDAT4 HURRICANE IVAN DISCUSSION NUMBER 36 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT SAT SEP 11 2004 A U.S. AIR FORCE RESERVE UNIT AIRCRAFT IS CURRENTLY FLYING IN THE HURRICANE. THE CENTRAL PRESSUURE IS 924 MB AND FLIGHT LEVEL WINDS SUPPORT 125 KT SURFACE WINDS. HOWEVER THE HURRICANE IS UNDERGOING AN EYEWALL REPLACEMENT CYCLE AND MAY SOON BE INTENSIFYING AND THE INITIAL WIND SPEED IS SET AT 130 KT. WITH LIGHT VERTICAL SHEAR AND WARM SSTS...CONDITIONS APPEAR FAVORABLE FOR STRENGHENING FOR THE NEXT DAY OR TWO AS IVAN THREATENS THE CAYMAN ISLANDS AND THEN CUBA. THE EYE TOOK A WESTWARD WOBBLE OVERNIGHT AND REMAINED FAR ENOUGH SOUTH OF JAMAICA SO THAT THE STRONGEST WINDS ARE BELIEVED TO HAVE REMAINED OFFSHORE. NEVERTHELESS...JAMAICA EXPERIENCED HURRICANE FORCE WINDS AND IS STILL DOING SO. THE GUIDANCE CONTINUES TO SHOW THE SAME FORECAST SCENARIO OF A TURN TOWARD THE NORTHWEST AND THEN NORTH THROUGH A WEAKNESS IN THE SUBTROPICAL RIDGE. THE RUNS OF THE FOUR GLOBAL TRACK GUIDANCE MODELS...GFS...GFDL...UKMET...NOGAPS...ALL SHIFTED THEIR TRACK A LITTLE TO THE LEFT. SOME OR ALL OF THE SHIFT COULD BE DUE TO THE SHORT TERM WESTWARD WOBBLE. THE OFFICIAL TRACK FORECAST IS ADJUSTED A LITTLE LEFT OF THE PREVIOUS ADVISORY BUT IS STILL TO THE RIGHT OR EAST OF ALL THE MODELS THROUGH 48 HOURS AND THEN IS CLOSER TO A CONSENSUS OF THE MODELS AFTER 48 HOURS. THE GUIDANCE MODELS INDICATE A DECREASE IN FORWARD SPEED FOR THE NEXT DAY OR SO AND SO DOES THE OFFICIAL FORECAST. FORECASTER LAWRENCE FORECAST POSITIONS AND MAX WINDS INITIAL 11/0900Z 17.5N 78.0W 130 KT 12HR VT 11/1800Z 18.3N 79.0W 135 KT 24HR VT 12/0600Z 19.3N 80.1W 140 KT 36HR VT 12/1800Z 20.6N 81.4W 140 KT 48HR VT 13/0600Z 22.0N 82.5W 140 KT 72HR VT 14/0600Z 25.9N 83.8W 115 KT 96HR VT 15/0600Z 30.5N 84.0W 90 KT...INLAND 120HR VT 16/0600Z 36.0N 83.0W 30 KT...INLAND |
