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| #540681 (Received by flhurricane at: 10:44 AM 06.Sep.2012) TCDAT2 HURRICANE LESLIE DISCUSSION NUMBER 29 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122012 1100 AM AST THU SEP 06 2012 SATELLITE INTENSITY ESTIMATES SUGGEST THAT THE CYCLONE IS BARELY A HURRICANE WITH AN INITIAL INTENSITY OF 65 KNOTS. LESLIE HAS A VERY LARGE CIRCULATION BUT LACKS AN INNER CORE. MOST OF THE THUNDERSTORM ACTIVITY IS CONCENTRATED IN CYCLONICALLY CURVED BANDS TO THE NORTH AND EAST OF THE CENTER DUE TO WESTERLY WIND SHEAR. GLOBAL MODELS HAVE BEEN VERY STUBBORN IN FORECASTING A RELAXATION OF THE SHEAR... ALTHOUGH THAT HAS NOT MATERIALIZED YET. HOWEVER...GIVING CREDIT TO THESE MODELS...AND THE FACT THAT THE SHIPS AND LGEM STATISTICAL MODELS ALSO DECREASE THE SHEAR...THE NHC FORECAST CALLS FOR STRENGTHENING TO BEGIN IN ABOUT 24 HOURS. THIS IS ALSO SUPPORTED BY THE FACT THAT LESLIE WILL BE MOVING OUT OF THE COOLER WATERS WHICH RESULTED FROM THE UPWELLING. LESLIE IS EMBEDDED WITHIN VERY LIGHT STEERING CURRENTS AND CONSEQUENTLY HAS BEEN MOVING VERY LITTLE OR MEANDERING NORTHWARD DURING THE PAST SEVERAL HOURS. THE STEERING CURRENTS ARE NOT FORECAST TO CHANGE MUCH DURING THE NEXT 24 TO 36 HOURS...BUT MOST OF THE GLOBAL MODELS BEGIN TO REDEVELOP THE SUBTROPICAL RIDGE TO THE EAST OF LESLIE AND BRING A LARGE MID-LATITUDE TROUGH OVER THE EASTERN UNITED STATES. THIS PATTERN SHOULD FORCE LESLIE TO MOVE NORTHWARD AND THEN NORTH-NORTHEASTWARD WITH AN INCREASE IN FORWARD SPEED DURING THE REMAINDER OF THE FORECAST PERIOD. ALTHOUGH THE TRACK MODELS ARE NOT IN GOOD AGREEMENT ON THE FORWARD SPEED... THE GENERAL MODEL TREND IS FOR A NORTHWARD AND NORTH-NORTHEASTWARD MOTION. THE WESTERN EDGE OF THE GUIDANCE ENVELOPE IS NEAR BERMUDA BUT THE CONSENSUS AS WELL AS THE GFS AND THE ECMWF MODELS SHOW A TRACK EAST OF BERMUDA. 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 FOR THE REMAINDER OF THIS WEEK. FORECAST POSITIONS AND MAX WINDS INIT 06/1500Z 26.4N 62.4W 65 KT 75 MPH 12H 07/0000Z 26.5N 62.4W 65 KT 75 MPH 24H 07/1200Z 26.8N 62.5W 70 KT 80 MPH 36H 08/0000Z 27.3N 62.8W 80 KT 90 MPH 48H 08/1200Z 28.2N 63.0W 85 KT 100 MPH 72H 09/1200Z 31.2N 62.8W 90 KT 105 MPH 96H 10/1200Z 35.0N 61.8W 90 KT 105 MPH 120H 11/1200Z 40.0N 59.0W 80 KT 90 MPH $$ FORECASTER AVILA |
