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| #8541 (Received by flhurricane at: 4:51 PM 15.Sep.2004) TCDAT1 TROPICAL STORM JEANNE DISCUSSION NUMBER 9 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 PM EDT WED SEP 15 2004 JEANNE TRIED TO FORM AN EYE IN BOTH RADAR AND SATELLITE IMAGERY JUST AS IT WAS MAKING LANDFALL IN SOUTHEASTERN PUERTO RICO. WSR-88D DATA FROM SAN JUAN INDICATES IT RETAINS A GOOD STRUCTURE ALTHOUGH THE CURRENT DOPPLER WINDS DO NOT SUPPORT SUSTAINED SURFACE WINDS OF HURRICANE FORCE. THIS AGREES WITH AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT...WHICH FOUND 57 KT FLIGHT-LEVEL WINDS AS IT FLEW AROUND THE PUERTO RICO COAST. THE INITIAL INTENSITY REMAINS 60 KT FOR THIS ADVISORY. THE INITIAL MOTION IS NOW 300/8. THERE IS LITTLE CHANGE IN THE TRACK FORECAST PHILOSOPHY. JEANNE IS CURRENTLY ON THE SOUTHERN PERIPHERY OF A DEEP LAYER RIDGE...AND MODEL GUIDANCE AGREES THAT THIS RIDGE SHOULD PERSIST AND MOVE JEANNE ON A CONTINUED WEST-NORTHWEST MOTION THROUGH ABOUT 48 HOURS. BEYOND THAT TIME...THE SOLUTIONS SOMEWHAT DIVERGE...OWING TO DIFFERENCES IN HOW EACH MODEL HANDLES A WEAKENING IVAN OVER THE SOUTHEASTERN UNITED STATES AND HOW MUCH RIDGING WILL REMAIN OVER THE EXTREME WESTERN ATLANTIC. MOST OF THE DYNAMICAL GUIDANCE CALLS FOR JEANNE TO TURN NORTHWESTWARD AND EVEN NORTHWARD AFTER 48 HR. WHILE THE GFDL IS STILL A LEFT OUTLIER...IT HAS SHIFTED CONSIDERABLY TO THE RIGHT IN BETTER AGREEMENT WITH THE OTHER MODELS.THE OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS PACKAGE WITH A LITTLE MORE NORTHWARD MOTION AFTER 72 HR. THE FORECAST TRACK IS TO THE LEFT OF ALL THE DYNAMICAL GUIDANCE SAVE THE GFDL AND FSU SUPERENSEMBLE. THE INTENSITY FORECAST REMAINS A CHALLENGE. WHILE THE OUTFLOW HAS IMPROVED THIS AFTERNOON...AN UPPER-LEVEL TROUGH OR CYCLONIC SHEAR AXIS IS CURRENTLY JUST WEST OF JEANNE. LARGE-SCALE MODELS HAVE A VARIETY OF IDEAS FOR THE EVOLUTION OF THIS FEATURE...FROM PERSISTING FOR THREE OR MORE DAYS TO QUICK DISSIPATION. MOST LIKELY ENOUGH THIS FEATURE WILL CREATE ENOUGH SHEAR TO AT LEAST SLOW INTENSIFICATION FOR 48-72 HR...AND THIS IS REFLECTED IN THE INTENSITY FORECAST. AFTER THAT...JEANNE SHOULD MOVE INTO A MORE FAVORABLE ENVIRONMENT AND GRADUALLY STRENGTHEN. ANOTHER COMPLICATION IS LAND INTERACTION. IF JEANNE MOVES OVER OR NEAR THE DOMINICAN REPUBLIC ALL BETS WILL BE OFF ON THE INTENSITY FORECAST. HURRICANE WARNINGS WILL REMAIN UP FOR PUERTO RICO AND THE VIRGIN ISLANDS UNTIL JEANNE MOVES AWAY...AS EVEN SLIGHT STRENGTHENING AS THE CENTER MOVES OFFSHORE COULD MAKE THE SYSTEM A HURRICANE. FORECASTER BEVEN FORECAST POSITIONS AND MAX WINDS INITIAL 15/2100Z 18.4N 66.5W 60 KT...OVER PUERTO RICO 12HR VT 16/0600Z 18.8N 67.7W 65 KT...OVER WATER 24HR VT 16/1800Z 19.7N 69.2W 65 KT 36HR VT 17/0600Z 20.6N 70.9W 65 KT 48HR VT 17/1800Z 21.6N 72.4W 70 KT 72HR VT 18/1800Z 23.5N 74.5W 75 KT 96HR VT 19/1800Z 26.0N 76.5W 80 KT 120HR VT 20/1800Z 29.5N 77.5W 85 KT |
