|
Show Selection: |
| #541692 (Received by flhurricane at: 11:02 PM 09.Sep.2012) TCDAT2 TROPICAL STORM LESLIE DISCUSSION NUMBER 43 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122012 1100 PM AST SUN SEP 09 2012 THE CONVECTIVE CLOUD PATTERN OF LESLIE HAS CONTINUED TO SLOWLY ERODE AND CLOUD TOPS HAVE ALSO CONTINUED TO WARM SINCE THE PREVIOUS ADVISORY. THE INITIAL INTENSITY REMAINS AT 50 KT BASED ON A BLEND OF DVORAK SATELLITE INTENSITY ESTIMATES OF T3.0/45 KT AND T3.5/55 KT FROM TAFB AND SAB...RESPECTIVELY. THE INITIAL MOTION ESTIMATE IS 015/14. THERE REMAINS NO SIGNIFICANT CHANGE TO THE PREVIOUS TRACK FORECAST AND REASONING. LESLIE IS EXPECTED TO CONTINUE MOVING NORTH-NORTHEASTWARD FOR THE NEXT 12 HOURS OR SO AS THE CYCLONE ROUNDS THE WESTERN PERIPHERY OF A DEEP-LAYER RIDGE LOCATED TO ITS EAST. BY 24 HOURS...LESLIE IS FORECAST TO ACCELERATE TO THE NORTHEAST BETWEEN INCREASING SOUTHWESTERLY FLOW AHEAD OF AN APPROACHING DEEP-LAYER TROUGH FROM THE WEST AND THE AFOREMENTIONED RIDGE TO THE EAST. BY DAYS 3-4... LESLIE WILL BE INTERACTING WITH A FRONTAL SYSTEM...AND THE POST-TROPICAL CYCLONE IS EXPECTED TURN EAST-NORTHEASTWARD AND EASTWARD IN THE HIGH-LATITUDE WESTERLY FLOW. ABSORPTION BY A LARGER EXTRATROPICAL LOW IS FORECAST TO OCCUR BY DAY 5 OVER THE NORTH SEA. THE OFFICIAL FORECAST TRACK IS CLOSE TO THE MIDDLE OF THE TIGHTLY PACKED NHC MODEL GUIDANCE. LESLIE CONTINUES TO LACK ANY INNER-CORE DEEP CONVECTION AND ALSO HAS A BROAD INNER-CORE WIND FIELD...WHICH SHOULD INHIBIT ANY SIGNIFICANT STRENGTHENING IN THE SHORT TERM. HOWEVER...AS THE CYCLONE BEGINS TO ACCELERATE RAPIDLY NORTHEASTWARD...THE ADDITIONAL FORWARD SPEED COMPONENT SHOULD INCREASE THE WIND SPEEDS IN THE EASTERN SEMICIRCLE. SINCE LESLIE IS FORECAST TO BE MOVING AT NEARLY 35 KT BY 36 HOURS...THIS COULD ALLOW THE CYCLONE TO ACHIEVE HURRICANE STATUS AGAIN BEFORE THE CYCLONE AFFECTS SOUTHEASTERN NEWFOUNDLAND. AFTER 36 HOURS...THE GLOBAL MODELS INDICATE THAT LESLIE WILL TRANSITION INTO A VIGOROUS EXTRATROPICAL CYCLONE AFTER IT MERGES WITH A STRONG FRONTAL SYSTEM BY DAY 2. LESLIE WILL REMAIN A POWERFUL EXTRATROPICAL CYCLONE UNTIL IT IS ABSORBED BY A LARGER EXTRATROPICAL LOW PRESSURE SYSTEM ON DAY 5. LONG-PERIOD SWELLS FROM LESLIE ARE EXPECTED TO PRODUCE ROUGH SURF AND LIFE-THREATENING RIP CURRENTS ON BERMUDA AND ALONG MUCH OF THE U.S. EAST COAST FOR THE NEXT COUPLE OF DAYS. OWING TO THE INCREASING FORWARD SPEED OF LESLIE FOR THE NEXT 36 HOURS...A HURRICANE WATCH WILL LIKELY REQUIRED EARLY FRIDAY MORNING FOR PORTIONS OF SOUTHEASTERN NEWFOUNDLAND...INCLUDING THE AVALON PENINSULA. FORECAST POSITIONS AND MAX WINDS INIT 10/0300Z 34.4N 61.8W 50 KT 60 MPH 12H 10/1200Z 36.8N 60.8W 55 KT 65 MPH 24H 11/0000Z 41.3N 58.2W 60 KT 70 MPH 36H 11/1200Z 47.5N 53.9W 65 KT 75 MPH...INLAND 48H 12/0000Z 54.1N 46.7W 60 KT 70 MPH...POST-TROP/EXTRATROP 72H 13/0000Z 62.5N 25.0W 60 KT 70 MPH...POST-TROP/EXTRATROP 96H 14/0000Z 62.5N 3.5W 50 KT 60 MPH...POST-TROP/EXTRATROP 120H 15/0000Z...ABSORBED BY LARGER EXTRATROPICAL LOW $$ FORECASTER STEWART |
