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| #213454 (Received by flhurricane at: 4:40 AM 04.Sep.2008) TCDAT5 TROPICAL STORM JOSEPHINE DISCUSSION NUMBER 9 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL102008 500 AM EDT THU SEP 04 2008 CONVENTIONAL AND MICROWAVE SATELLITE IMAGERY INDICATE THAT DEEP CONVECTION HAS REDEVELOPED IN THE NORTHERN SEMICIRCLE AND THAT THE LOW-LEVEL CENTER HAS MOVED FURTHER INTO THE SOUTHERN PORTION OF THE CONVECTIVE CLOUD MASS. SATELLITE INTENSITY ESTIMATES ARE T3.5/55 KT AND T3.0/45 KT FROM TAFB AND SAB...RESPECTIVELY...SO THE INITIAL INTENSITY HAS BEEN INCREASED TO 50 KT. HOWEVER...IF THE LOW-LEVEL CENTER IS FARTHER NORTH INTO THE CONVECTION...THEN JOSEPHINE WILL BE STRONGER THAN INDICATED IN THIS ADVISORY. THE INITIAL MOTION ESTIMATE IS 285/9...BASED MAINLY ON MICROWAVE SATELLITE POSITION ESTIMATES OVER THE PAST 9 HOURS. JOSEPHINE IS FORECAST TO MOVE IN A GENERAL WEST-NORTHWESTWARD MOTION ALONG THE SOUTHERN PERIPHERY OF LARGE SUBTROPICAL RIDGE FOR THE NEXT 48-72 HOURS. AFTER THAT...A WEAKNESS IS FORECAST TO DEVELOP IN THE RIDGE ...WHICH SHOULD ALLOW JOSEPHINE TO MAKE A POLEWARD JOG AT DAYS 3 AND 4...BEFORE THE RIDGE FILLS BACK IN FORCING THE CYCLONE ON A LITTLE MORE WESTWARD BY 120 HOURS. THE OFFICIAL FORECAST TRACK IS TO THE RIGHT OF THE PREVIOUS TRACK...BUT REMAINS TO THE LEFT OF THE MODEL CONSENSUS AND CONTINUES ALONG THE SOUTHERN EDGE OF THE NHC MODEL GUIDANCE ENVELOPE. ALTHOUGH JOSEPHINE IS EXPERIENCING SOUTH-SOUTHWESTERLY VERTICAL WIND SHEAR OF 20 TO 25 KT...THE CYCLONE IS LOCATED IN A REGION OF MODERATE DIFLUENCE IN SOUTHEASTERN QUADRANT OF A LARGE UPPER-LEVEL LOW THAT IS SITUATED ABOUT MIDWAY BETWEEN JOSEPHINE AND MAJOR HURRICANE IKE. THIS UPPER-AIR PATTERN IS FORECAST TO PROPAGATE WESTWARD IN TANDEM WITH JOSEPHINE AND IKE FOR THE NEXT 48 HOURS... AFTER WHICH THE UPPER-LEVEL LOW IS EXPECTED TO GRADUALLY FILL AND LIFT OUT TO THE NORTH. THE SHIPS INTENSITY MODEL MAINTAINS SOUTHERLY SHEAR OF ABOUT 20 KT THROUGH 72 HOURS...AND THEN INDICATES THE VERTICAL SHEAR WILL DECREASE TO 10 TO 15 KT AFTER THAT. THE OFFICIAL FORECAST FOLLOWS THE SHIPS MODEL BY HOLDING THE INTENSITY STEADY THROUGHOUT THE FORECAST PERIOD. HOWEVER...IF JOSEPHINE REMAINS NEAR OR SOUTH OF 20N LATITUDE BY DAYS 4 AND 5...THEN THE CYCLONE WILL BE BENEATH UPPER-LEVEL ANTICYCLONIC FLOW AND WEAK SHEAR...WHICH WOULD ALLOW FOR STRENGTHENING TO OCCUR. THIS SCENARIO WILL BE EVALUATED IN SUBSEQUENT FORECAST PACKAGES. FORECAST POSITIONS AND MAX WINDS INITIAL 04/0900Z 14.2N 31.3W 50 KT 12HR VT 04/1800Z 14.5N 32.9W 50 KT 24HR VT 05/0600Z 15.0N 35.0W 50 KT 36HR VT 05/1800Z 15.7N 37.1W 50 KT 48HR VT 06/0600Z 16.4N 39.1W 50 KT 72HR VT 07/0600Z 17.9N 42.8W 50 KT 96HR VT 08/0600Z 19.5N 47.0W 50 KT 120HR VT 09/0600Z 21.0N 51.5W 50 KT $$ FORECASTER STEWART |
