000 WTPZ44 KNHC 110234 TCDEP4 HURRICANE FLOSSIE DISCUSSION NUMBER 10 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP092007 800 PM PDT FRI AUG 10 2007 WHILE FLOSSIE HAS MAINTAINED ITS CONVECTIVE VIGOR...THE EYE IS NOW A BIT RAGGED. STILL...THIS COULD BE A TEMPORARY TREND AND THE INITIAL INTENSITY IS HELD AT 75 KT IN LINE WITH A CONSENSUS OF THE VARIOUS SATELLITE ESTIMATES. CONDITIONS APPEAR FAVORABLE FOR A LITTLE MORE STRENGTHENING AND INTENSITY GUIDANCE INDICATES THAT FLOSSIE WILL REACH ITS PEAK INTENSITY DURING THE NEXT DAY OR SO. THEREAFTER...SLOW WEAKENING IS EXPECTED AS THE CYCLONE ENCOUNTERS COOLER WATER AND AN INCREASE IN VERTICAL SHEAR. THERE IS SOME DIFFERENCE IN THE HOW THE GLOBAL MODELS RESOLVE THE UPPER-LEVEL FLOW TOWARDS THE END OF THE FORECAST LEADING TO UNCERTAINTY IN THE EVENTUAL IMPACT OF VERTICAL SHEAR. THE OFFICIAL INTENSITY FORECAST IS ESSENTIALLY UNCHANGED AND IS VERY CLOSE TO THE FLORIDA STATE SUPER ENSEMBLE. FLOSSIE CONTINUES TO BE STEERED BY A SUBTROPICAL RIDGE TO ITS NORTH WITH AN ALMOST DUE WESTWARD MOTION OR 275 DEGREES AT ABOUT 11 KT. TRACK MODEL GUIDANCE REMAINS SOMEWHAT DIVERGENT WITH SOME RUN TO RUN INCONSISTENCY. THE HWRF HAS SHIFTED SOUTH WHILE THE NOGAPS HAS SHIFTED NORTH. THE BIGGEST DIFFERENCE BETWEEN THE VARIOUS TRACK MODELS IS THE FORECAST STRENGTH OF THE SUBTROPICAL RIDGE...AND THE EVENTUAL STRENGTH AND DEPTH OF THE CYCLONE. THE GFDL CONTINUES TO LIE ALONG THE NORTHERN SIDE OF THE GUIDANCE ENVELOPE BUT IT SHOWS FLOSSIE MAINTAINING HURRICANE STRENGTH LONGER THAN THE OTHER MODELS DESPITE ITS TRACK OVER COOLER WATERS. ADDITIONALLY...THE GFDL HAS CONSISTENTLY DEMONSTRATED A NORTHWARD BIAS FOR THIS STORM. THE EUROPEAN MODEL CONTINUES TO LIE ALONG THE SOUTH SIDE OF THE MODEL GUIDANCE BUT IT SHOWS FLOSSIE SHEARING APART AT DAYS 4 AND 5. IT IS MUCH TOO SOON TO DECIDE WHICH OF THESE TWO SCENARIOS IS MOST LIKELY SO THE OFFICIAL FORECAST IS LARGELY UNCHANGED FROM THE PREVIOUS ADVISORY...EXCEPT A LITTLE SLOWER BEYOND DAY 3. FORECAST POSITIONS AND MAX WINDS INITIAL 11/0300Z 12.7N 138.3W 75 KT 12HR VT 11/1200Z 12.9N 140.0W 80 KT 24HR VT 12/0000Z 13.4N 142.3W 80 KT 36HR VT 12/1200Z 13.9N 144.6W 75 KT 48HR VT 13/0000Z 14.4N 146.9W 70 KT 72HR VT 14/0000Z 15.5N 151.5W 60 KT 96HR VT 15/0000Z 17.0N 155.5W 50 KT 120HR VT 16/0000Z 18.5N 159.0W 40 KT $$ FORECASTER RHOME