Show Selection: |
#540953 (Received by flhurricane at: 10:53 AM 07.Sep.2012) TCDAT2 TROPICAL STORM LESLIE DISCUSSION NUMBER 33 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122012 1100 AM AST FRI SEP 07 2012 LESLIE HAS BEEN NEARLY STATIONARY TOO LONG AND THE OCEAN BENEATH HAS COOLED SIGNIFICANTLY. IN FACT...ONE OF THE AXBT SONDES LAUNCHED FROM THE NOAA PLANE CURRENTLY IN LESLIE MEASURED A SEA SURFACE TEMPERATURE OF 24.5 DEGREES CELSIUS. CONSEQUENTLY...THE CONVECTION HAS DIMINISHED AND THE CLOUD PATTERN HAS BECOME LESS ORGANIZED. THE NOAA HURRICANE HUNTER AIRCRAFT ALSO MEASURED A MINIMUM PRESSURE OF 981 MB...BUT BOTH SFMR AND FLIGHT LEVEL WINDS ONLY SUPPORT AN INITIAL INTENSITY OF 60 KNOTS. ONCE LESLIE MOVES AWAY FROM THE COOL POOL IT HAS CREATED FOR ITSELF...THE CYCLONE WILL HAVE THE OPPORTUNITY TO REGAIN HURRICANE STATUS SINCE THE SHEAR IS EXPECTED TO BE LOW. BY THE END OF THE FORECAST PERIOD...LESLIE SHOULD HAVE LOST TROPICAL CHARACTERISTICS AND BECOME A STRONG POST-TROPICAL CYCLONE. THE STEERING CURRENTS COLLAPSED A COUPLE OF DAYS AGO RESULTING IN LESLIE BEING NEARLY STATIONARY. GLOBAL MODELS ARE SHOWING A LARGE MID-LEVEL TROUGH MOVING EASTWARD ACROSS THE EASTERN UNITED STATES AND CANADA. THIS TROUGH SHOULD ACCELERATE THE SOUTHERLY FLOW THAT EVENTUALLY WILL FORCE LESLIE TO MOVE NORTHWARD AND THEN NORTH-NORTHEASTWARD WITH AN INCREASING FORWARD SPEED DURING THE NEXT FEW DAYS. THE TRACK GUIDANCE IS MORE CONSISTENT WITH THIS SOLUTION PRIMARILY IN THE FIRST 3 DAYS. THE NHC FORECAST IS VERY CLOSE TO THE MODEL CONSENSUS AND IS A BLEND OF THE GFS AND THE ECMWF. THE WIND FIELD OF LESLIE...COMBINED WITH ITS EXPECTED SLOW MOTION... WILL GENERATE LONG-PERIOD SWELLS THAT WILL PRODUCE LARGE WAVES AND LIFE-THREATENING RIP CURRENTS ON BERMUDA AND ALONG MUCH OF THE U.S. EAST COAST THROUGH THE WEEKEND. FORECAST POSITIONS AND MAX WINDS INIT 07/1500Z 26.8N 62.2W 60 KT 70 MPH 12H 08/0000Z 27.1N 62.2W 60 KT 70 MPH 24H 08/1200Z 28.0N 62.2W 60 KT 70 MPH 36H 09/0000Z 29.0N 62.2W 70 KT 80 MPH 48H 09/1200Z 30.5N 61.9W 80 KT 90 MPH 72H 10/1200Z 33.3N 60.8W 85 KT 100 MPH 96H 11/1200Z 39.0N 57.0W 75 KT 85 MPH 120H 12/1200Z 45.5N 53.5W 60 KT 70 MPH...POST-TROP/EXTRATROP $$ FORECASTER AVILA |