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| #539810 (Received by flhurricane at: 10:53 AM 03.Sep.2012) TCDAT2 TROPICAL STORM LESLIE DISCUSSION NUMBER 17 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122012 1100 AM AST MON SEP 03 2012 LESLIE CONTINUES TO BE AFFECTED BY ABOUT 15 KT OF NORTHWESTERLY SHEAR...ACCORDING TO ANALYSIS FROM UW-CIMSS. THIS SHEAR HAS CAUSED THE CONVECTIVE PATTERN TO BE QUITE ASYMMETRIC WITH NEARLY ALL OF THE COLD CLOUD TOPS CONFINED TO THE SOUTHEASTERN PORTION OF THE CIRCULATION. THERE HAS BEEN LITTLE CHANGE IN THE DVORAK CLASSIFICATIONS THIS CYCLE...SO THE INITIAL INTENSITY IS HELD AT 50 KT. THE SHIPS MODEL SHOWS THE SHEAR INCREASING A LITTLE OVER THE NEXT 24 HOURS...WHICH SHOULD LIMIT THE STORM FROM STRENGTHENING DURING THAT TIME PERIOD. AFTER THAT...HOWEVER...THE SHEAR IS EXPECTED TO RELAX AND GIVEN THAT THE OTHER ATMOSPHERIC AND OCEANIC CONDITIONS APPEAR FAVORABLE...LESLIE WILL LIKELY HAVE AN OPPORTUNITY TO GAIN STRENGTH. THE OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS ONE AND BASICALLY A BLEND OF THE SHIPS AND LGEM GUIDANCE. RECENT MICROWAVE DATA AND VISIBLE SATELLITE IMAGES INDICATE THAT THE CENTER OF LESLIE WAS LOCATED A LITTLE TO THE WEST OF THE PREVIOUS TRACK. BLENDING THE MICROWAVE DATA WITH EARLIER SATELLITE FIXES YIELDS AN INITIAL MOTION ESTIMATE OF 330/7. LESLIE IS CURRENTLY MOVING TOWARD A DEEP-LAYER TROUGH TO ITS NORTH. THIS TROUGH IS EXPECTED TO SHIFT TO THE EAST...CAUSING THE STEERING CURRENTS TO WEAKEN DURING THE NEXT DAY OR SO. THEREFORE...LESLIE IS ONLY EXPECTED TO DRIFT NORTHWARD DURING THE 24 TO 72 HOUR TIME PERIOD. LATE IN THE WEEK...THE COMBINED INFLUENCES OF A MID- TO UPPER-LEVEL LOW OFF THE SOUTHEAST U.S. COAST AND A RIDGE TO THE EAST OF LESLIE SHOULD CAUSE THE CYCLONE TO MOVE NORTH-NORTHWESTWARD OR NORTHWARD AT A FASTER PACE. THE OFFICIAL FORECAST IS ADJUSTED ABOUT 30 N MI TO THE WEST OF THE PREVIOUS TRACK DUE TO THE MORE WESTWARD INITIAL POSITION. DUE TO THE LARGE SIZE OF THE CYCLONE AND EXPECTED SLOW MOTION... LARGE SWELLS PROPAGATING AWAY FROM THE TROPICAL CYCLONE WILL AFFECT BERMUDA AND NEARLY ALL OF THE U.S. EAST COAST FOR MUCH OF THE WEEK. FORECAST POSITIONS AND MAX WINDS INIT 03/1500Z 24.4N 63.1W 50 KT 60 MPH 12H 04/0000Z 25.2N 63.2W 50 KT 60 MPH 24H 04/1200Z 25.8N 63.3W 50 KT 60 MPH 36H 05/0000Z 26.3N 63.4W 55 KT 65 MPH 48H 05/1200Z 26.8N 63.5W 55 KT 65 MPH 72H 06/1200Z 27.7N 63.6W 65 KT 75 MPH 96H 07/1200Z 29.0N 64.0W 75 KT 85 MPH 120H 08/1200Z 31.5N 64.5W 80 KT 90 MPH $$ FORECASTER CANGIALOSI |
