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| #110253 (Received by flhurricane at: 4:52 PM 11.Sep.2006) TCDAT2 TROPICAL STORM GORDON DISCUSSION NUMBER 4 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL072006 500 PM EDT MON SEP 11 2006 AN AIR FORCE RECONNAISSANCE AIRCRAFT HAS BEEN INVESTIGATING THE TROPICAL CYCLONE AND REPORTED PEAK FLIGHT LEVEL WINDS OF 47 KT WHICH REDUCES TO 38 KT AT THE SURFACE. THUS THE SYSTEM IS BEING UPGRADED TO TROPICAL STORM GORDON ON THIS ADVISORY WITH AN INITIAL INTENSITY OF 40 KT. THE UPGRADE IS ALSO SUPPORTED BY DVORAK SATELLITE INTENSITY ESTIMATES OF 35 KT FROM SAB...TAFB AND AFWA. SINCE THE TIME OF THE FIRST AIRCRAFT FIX THE OVERALL SATELLITE PRESENTATION HAS IMPROVED WITH INCREASING BANDING FEATURES AND EXPANDING OUTFLOW. THE INITIAL MOTION IS 310/8...SLIGHTLY FASTER AND TO THE RIGHT OF THE PREVIOUS ADVISORY. THE TRACK GUIDANCE IS DIVIDED INTO 2 CAMPS...THE BAMS ON THE LEFT AND THE VARIOUS DYNAMICAL MODELS AND CONSENSUS TO THE RIGHT. THE FORECAST TRACK IS ADJUSTED TO THE RIGHT OUT OF RESPECT FOR THE DYNAMICAL GUIDANCE AND SLIGHTLY FASTER THAN THE PREVIOUS ADVISORY BASED ON THE INITIAL MOTION. THE GLOBAL MODELS ARE ALL IN AGREEMENT IN TURNING THE SYSTEM MORE NORTHWARD AND HEADING FOR A BREAK IN THE SUBTROPICAL RIDGE. THE GFS IS AN OUTLIER AND TRAPS THE SYSTEM BENEATH THE SUBTROPICAL RIDGE LATE IN THE FORECAST. THIS SOLUTION SEEMS UNLIKELY AND IS IN PART DUE TO POOR INITIALIZATION OF THE SYSTEM BY THAT MODEL WHICH ALSO DISSIPATES GORDON WITHIN 72 HOURS. THE INTENSITY FORECAST IS HIGHER THAN IN THE PREVIOUS ADVISORY GIVEN THE SYSTEM'S INITIAL INTENSITY OF 40 KT AND DECREASING ENVIRONMENTAL SHEAR. GIVEN THE MORE CONDUCIVE CONDITIONS AND INCREASED ORGANIZATION OF THE SYSTEM...MORE SIGNIFICANT STRENGTHENING SEEMS LIKELY THAN PREVIOUSLY INDICATED. GORDON COULD BECOME A HURRICANE IN A COUPLE OF DAYS. THE INTENSITY FORECAST IS NOT QUITE AS AGGRESSIVE AS THE FSU SUPERENSEMBLE AND IS IN REASONABLE AGREEMENT WITH SHIPS AND THE GFDL HURRICANE MODEL. FORECAST POSITIONS AND MAX WINDS INITIAL 11/2100Z 21.6N 57.3W 40 KT 12HR VT 12/0600Z 22.4N 58.3W 45 KT 24HR VT 12/1800Z 23.7N 59.3W 55 KT 36HR VT 13/0600Z 25.0N 60.1W 60 KT 48HR VT 13/1800Z 26.5N 60.5W 65 KT 72HR VT 14/1800Z 29.0N 60.5W 70 KT 96HR VT 15/1800Z 31.5N 60.0W 70 KT 120HR VT 16/1800Z 34.0N 59.5W 70 KT $$ FORECASTER COBB/PASCH |
