000 WTNT44 KNHC 150233 TCDAT4 HURRICANE IVAN DISCUSSION NUMBER 51 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 PM EDT TUE SEP 14 2004 OBSERVATIONS FROM AIR FORCE AND NOAA RECONNAISSANCE AIRCRAFT INDICATE THAT IVAN IS MAINTAINING 120 KT...CAT. 4...INTENSITY. WATER VAPOR IMAGERY AND GPS DROPSONDE OBSERVATIONS FROM THE NOAA G-IV JET INDICATE STRONG UPPER-LEVEL OUTFLOW AS WELL. THERE IS THE POSSIBILITY THAT THE HURRICANE CORE WILL PASS OVER SOME HIGHER HEAT CONTENT WATERS DURING THE NEXT 24 HOURS...SO SOME STRENGTHENING IS POSSIBLE ON WEDNESDAY. AS THE HURRICANE NEARS THE COAST...A SHALLOWER LAYER OF WARM WATERS AND SOME INCREASE IN VERTICAL SHEAR COULD CAUSE SLIGHT WEAKENING. HOWEVER...WE EMPHASIZE THAT IVAN IS EXPECTED TO BE A VERY POWERFUL AND DANGEROUS HURRICANE AT LANDFALL. INITIAL MOTION IS A LITTLE FASTER...NOW 340/10. THE TRACK FORECAST REASONING AND NUMERICAL GUIDANCE REMAINS BASICALLY UNCHANGED FROM THE PREVIOUS PACKAGE. IVAN IS BEING STEERED MAINLY BY THE FLOW ON THE WEST SIDE OF A MID-TROPOSPHERIC RIDGE. THERE IS GOOD AGREEMENT AMONGST THE GFDL...GFS...UKMET...NOGAPS...AND GFDN MODELS ON THE PREDICTED TRACK FOR THE NEXT 36 HOURS. THE CURRENT OFFICIAL FORECAST TRACK FOLLOWS A CONSENSUS OF THE AFOREMENTIONED 5 DYNAMICAL MODELS...AND IS SIMILAR TO THE FORECAST FROM THE PREVIOUS ADVISORY. LATE IN THE FORECAST PERIOD...GLOBAL MODEL GUIDANCE SUGGESTS THAT IVAN WILL NOT GET PICKED UP BY THE WESTERLIES BUT RATHER WILL STALL OR MOVE ERRATICALLY NEAR THE SOUTHERN APPALACHIANS. SO THIS OFFICIAL FORECAST...LIKE THE PREVIOUS ONE... SHOWS NO MOVEMENT AT DAYS 4 AND 5. SINCE IVAN IS SO LARGE AND INTENSE...IT HAS THE POTENTIAL TO CARRY STRONG AND DAMAGING WINDS WELL INLAND ALONG ITS PATH. NOTE THAT THE OFFICIAL FORECAST INDICATES THAT THE SYSTEM WILL STILL BE AT HURRICANE STRENGTH 12 HOURS AFTER LANDFALL. FORECASTER PASCH FORECAST POSITIONS AND MAX WINDS INITIAL 15/0300Z 25.1N 87.2W 120 KT 12HR VT 15/1200Z 26.6N 87.8W 125 KT 24HR VT 16/0000Z 28.6N 88.2W 125 KT 36HR VT 16/1200Z 30.6N 88.2W 120 KT...INLAND 48HR VT 17/0000Z 32.6N 87.6W 70 KT...INLAND 72HR VT 18/0000Z 35.0N 85.5W 30 KT...INLAND 96HR VT 19/0000Z 35.5N 85.0W 20 KT...INLAND 120HR VT 20/0000Z 35.5N 85.0W 20 KT...INLAND $$