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#8658 (Received by flhurricane at: 11:03 PM 15.Sep.2004) TCDAT4 HURRICANE IVAN DISCUSSION NUMBER 55 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 PM EDT WED SEP 15 2004 THE EYE REMAINS WELL-DEFINED ON SATELLITE IMAGES...BUT ON THE MOBILE WSR-88D RADAR...THERE HAS BEEN AN EROSION OF THE SOUTHWEST EYEWALL. ALSO...THE NOAA PLANE REPORTED THAT THE EYEWALL WAS OPEN TO THE SOUTHWEST. GPS DROPSONDE DATA AT 200 MB FROM THIS EVENING'S NOAA G-IV JET MISSION DO NOT SUGGEST MUCH VERTICAL SHEAR IN THE ENVIRONMENT OF IVAN...ALTHOUGH THERE IS SOME WESTERLY FLOW INTO THE HURRICANE AT 250 AND 300 MB. NO LARGE CHANGES IN STRENGTH ARE LIKELY UNTIL THE CENTER REACHES THE COAST...AND IVAN IS EXPECTED TO MAKE LANDFALL AS A MAJOR HURRICANE. OVER THE LAST FEW HOURS THE MOTION HAS BEEN SLIGHTLY EAST OF NORTH...ABOUT 010/010. BECAUSE OF THIS SLIGHT EASTWARD SHIFT IN HEADING...THE TRACK HAS BEEN ADJUSTED SLIGHTLY TO THE RIGHT. THIS REMAINS CLOSE TO THE CONSENSUS OF THE TRACK MODELS AS WELL AS THE LATEST FSU SUPERENSEMBLE RUN. SINCE IVAN IS SO LARGE AND INTENSE...IT IS EXPECTED TO BRING HURRICANE FORCE WINDS WELL INLAND...UP TO ABOUT 150 MILES ALONG ITS TRACK. NOTE THAT THE INLAND GUST FACTOR IS QUITE LARGE BECAUSE HIGH MOMENTUM AIR...ALOFT...CAN BE BROUGHT TO THE SURFACE IN THE CONVECTIVE CELLS. LATER IN THE PERIOD...THE DYNAMICAL MODELS SHOW THE FORWARD PROGRESS OF IVAN BEING BLOCKED. THEREFORE THE OFFICIAL FORECAST SHOWS IVAN STALLING NEAR THE SOUTHERN APPALACHIANS AND SLOWLY DISSIPATING IN THAT AREA. OBVIOUSLY THIS COULD BE A MAJOR FLOOD EVENT OVER PORTIONS OF THE SOUTHEASTERN U.S. IN THE COMING DAYS. FORECASTER PASCH FORECAST POSITIONS AND MAX WINDS INITIAL 16/0300Z 29.3N 88.1W 115 KT 12HR VT 16/1200Z 31.0N 87.9W 110 KT...INLAND 24HR VT 17/0000Z 33.0N 87.2W 60 KT...INLAND 36HR VT 17/1200Z 34.5N 86.5W 30 KT...INLAND 48HR VT 18/0000Z 35.5N 85.5W 25 KT...INLAND 72HR VT 19/0000Z 36.0N 84.0W 20 KT...INLAND 96HR VT 20/0000Z 36.0N 84.0W 20 KT...DISSIPATING 120HR VT 21/0000Z...DISSIPATED |