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| #6824 (Received by flhurricane at: 11:04 AM 31.Aug.2004) TCDAT1 HURRICANE FRANCES DISCUSSION NUMBER 27 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 AM EDT TUE AUG 31 2004 THE LAST RECONNAISSANCE PLANE EARLIER THIS MORNING REPORTED A MAXIMUM FLIGHT LEVEL WIND OF 138 KNOTS AT 700 MB AND A MINIMUM PRESSURE OF 950 MB FROM A DROP AND AN EXTRAPOLATED PRESSURE OF 944 MB. SATELLITE IMAGES SHOW THAT FRANCES HAS AN OUTSTANDING CLOUD PATTERN WITH A LARGE EYE...BANDING FEATURES AND EXCELLET OUTFLOW. THE LARGE EYE CAN ALSO BE OBSERVED IN THE SAN JUAN PUERTO RICO DOPPLER RADAR. INITIAL INTENSITY HAS BEEN INCREASED TO 115 KNOTS. SINCE THE SHEAR IS LOW AND THE OCEAN IS WARM...SOME ADDITIONAL STRENGTHENING IS POSSIBLE. HOWEVER...FUTURE CHANGES IN INTENSITY WILL PROBABLY BE CONTROLLED BY EYEWALL REPLACEMENT CYCLES...A PROCESS RATHER DIFFICULT TO FORECAST. THE BEST OPTION AT THIS TIME IS TO FORECAST FLUCTUATIONS IN INTENSITY AND KEEP THE HURRICANE AS A CATEGORY 4 ON THE SAFFIR/SIMPSON HURRICANE SCALE. FRANCES IS MOVING WESTWARD OR 275 DEGREES AT 13 KNOTS. DURING THE THE FIRST 2 TO 3 DAYS...THE HURRICANE WILL BE MOVING BETWEEN THE WEST AND WEST-NORTHWEST STEERED BY A STRONG SUBTROPICAL RIGDE. THEREAFTER...THE INTENSITY OF THE RIDGE VARIES WITH THE DIFFERENT MODELS. CONSEQUENTLY...SOME MODELS BRING THE HURRICANE FARTHER WEST OR CLOSER TO THE U.S. COAST THAN OTHERS. OVERALL...THE TREND OF THE MODELS SINCE YESTERDAY IS TO TURN THE CYCLONE TO THE NORTHWEST EARLIER AND NONE OF THE RELIABLE GLOBAL MODELS EXCEPT THE ECMWF BRING THE HURRICANE TO EXTREME SOUTH FLORIDA OR THE KEYS. THE MOST SIGNIFICANT CHANGE TO THE RIGHT IS PRODUCED BY THE GFS WHICH BARELY BRINGS THE HURRICANE NEAR THE NORTHEAST FLORIDA COAST. HOWEVER...IT IS NORMAL FOR MODELS TO VARY FROM RUN TO RUN AND I WOULD RATHER WAIT FOR ANOTHER MODEL CYCLE TO ADJUST THE FORECAST MORE THE RIGHT...IF NECESSARY. FORECASTER AVILA FORECAST POSITIONS AND MAX WINDS INITIAL 31/1500Z 20.0N 64.0W 115 KT 12HR VT 01/0000Z 20.4N 66.1W 120 KT 24HR VT 01/1200Z 21.5N 68.7W 125 KT 36HR VT 02/0000Z 22.5N 71.0W 125 KT 48HR VT 02/1200Z 23.5N 73.0W 125 KT 72HR VT 03/1200Z 25.5N 76.5W 125 KT 96HR VT 04/1200Z 27.5N 79.0W 125 KT 120HR VT 05/1200Z 30.5N 81.5W 115 KT |
