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| #213611 (Received by flhurricane at: 4:41 PM 04.Sep.2008) TCDAT5 TROPICAL STORM JOSEPHINE DISCUSSION NUMBER 11 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL102008 500 PM EDT THU SEP 04 2008 JOSEPHINE CURRENTLY CONSISTS OF A LARGE SWIRL OF LOW/MID-LEVEL CLOUDS THAT IS VOID OF ORGANIZED CONVECTION. INDEED...THE ONLY CONVECTION IN THE SYSTEM AT THIS TIME ARE A FEW CELLS WELL TO THE SOUTHWEST AND NORTHEAST OF THE CENTER. ANALYSES FROM CIMSS AT THE UNIVERSITY OF WISCONSIN SHOW THAT JOSEPHINE CONTINUES TO EXPERIENCE ABOUT 20 KT OF SOUTHWESTERLY VERTICAL WIND SHEAR. THE INITIAL INTENSITY IS REDUCED TO 40 KT BASED ON A BLEND OF INTENSITY ESTIMATES FROM TAFB AND SAB...AND 35-40 KT WINDS SEEN IN AN ASCAT PASS NEAR 12Z. THE INITIAL MOTION REMAINS 285/9. AGAIN...THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS ADVISORY. JOSEPHINE IS FORECAST TO MOVE IN A GENERAL WEST-NORTHWESTWARD MOTION ALONG THE SOUTHERN PERIPHERY OF A LARGE SUBTROPICAL RIDGE FOR THE NEXT 36-48 HOURS. AFTER THAT...A WEAKNESS IS FORECAST TO DEVELOP IN THE RIDGE...WHICH SHOULD ALLOW JOSEPHINE TO MAKE A NORTHWARD JOG AT 72-96 HR...BEFORE THE RIDGE FILLS BACK IN FORCING THE CYCLONE A LITTLE MORE WESTWARD BY 120 HOURS. WHILE THE GUIDANCE IS IN BETTER AGREEMENT ON THE SPEED THIS TIME...THERE IS SOME SPREAD IN THE DIRECTION. THE BAMD...NOGAPS...GFDL...AND HWRF CALL FOR A NORTHWESTERLY MOTION...WHILE THE UKMET...GFS...AND BAMS ARE AT THE OTHER EDGE OF THE ENVELOPE CALLING FOR A WEST-NORTHWESTWARD MOTION. THE NEW FORECAST TRACK IS SIMILAR TO THE PREVIOUS TRACK AND LIES ALONG THE SOUTH SIDE OF THE GUIDANCE IN BEST AGREEMENT WITH THE UKMET AND BAMS. THE LARGE-SCALE MODELS CONTINUE TO DISAGREE ON WHETHER THE SHEAR OVER JOSEPHINE WILL LET UP. THE GFS FORECASTS UPPER-LEVEL WINDS TO BECOME MORE FAVORABLE AFTER 48 HR...WHILE THE UKMET FORECAST A RATHER HOSTILE LOOKING UPPER-LEVEL WIND PATTERN. IN ADDITION...THE FORECAST TRACK TAKES THE SYSTEM OVER PROGRESSIVELY COOLER WATER FOR 60 HR BEFORE THE SEA SURFACE TEMPERATURES START INCREASING. THE INTENSITY FORECAST CALLS FOR A LITTLE MORE WEAKENING...THEN HOLDING JOSEPHINE AT 35 KT THROUGH 72 HR. THEREAFTER...IF THE GFS/ SHIPS MODELS ARE CORRECT ABOUT THE SHEAR DECREASING...SOME RE-INTENSIFICATION IS POSSIBLE. AN ALTERNATIVE SCENARIO...FAVORED BY THE HWRF AND GFDN...IS THAT JOSEPHINE COULD DISSIPATE DURING THE NEXT 5 DAYS IF THE CONVECTION DOES NOT PERSIST. FORECAST POSITIONS AND MAX WINDS INITIAL 04/2100Z 14.6N 33.2W 40 KT 12HR VT 05/0600Z 14.9N 34.4W 35 KT 24HR VT 05/1800Z 15.3N 35.9W 35 KT 36HR VT 06/0600Z 15.8N 37.5W 35 KT 48HR VT 06/1800Z 16.5N 39.3W 35 KT 72HR VT 07/1800Z 18.5N 43.0W 35 KT 96HR VT 08/1800Z 20.5N 47.0W 40 KT 120HR VT 09/1800Z 22.0N 50.5W 45 KT $$ FORECASTER BEVEN |
