000 WTNT42 KNHC 080846 TCDAT2 TROPICAL STORM LESLIE DISCUSSION NUMBER 36 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122012 500 AM AST SAT SEP 08 2012 LESLIE SHOWED SOME SIGNS OF PERHAPS GETTING BETTER ORGANIZED EARLIER TONIGHT...WITH CONVECTIVE BANDS TRYING TO WRAP AROUND THE SOUTH SIDE OF THE CENTER. HOWEVER...THE CLOUD PATTERN HAS RECENTLY BECOME MORE RAGGED AND THE COLDEST TOPS ARE DISPLACED WEST AND NORTH OF THE CENTER LOCATION. DROPSONDE DATA FROM THE AIRCRAFT MISSIONS LAST NIGHT AND SATELLITE IMAGERY SHOW SOME DRY AIR WRAPPING INTO THE SOUTHERN PORTION OF THE CIRCULATION...WHICH IS LIKELY HINDERING INTENSIFICATION FOR THE TIME BEING. THE INITIAL INTENSITY REMAINS 55 KT IN AGREEMENT WITH THE LATEST DVORAK ESTIMATE FROM TAFB. THE INTENSITY FORECAST REASONING REMAINS UNCHANGED...AS DRY AIR AND RELATIVELY COOL WATERS SHOULD LEAD TO ONLY GRADUAL STRENGTHENING IN THE NEXT DAY OR SO. AFTER THAT TIME...AS LESLIE MOVES OVER WARMER WATERS...STEADIER INTENSIFICATION IS EXPECTED THROUGH 72 HOURS. AT DAYS 4 AND 5 LESLIE SHOULD WEAKEN AS THE SHEAR INCREASES WHILE THE CYCLONE MOVES NORTH OF THE GULF STREAM AND UNDERGOES EXTRATROPICAL TRANSITION. THE NHC FORECAST IS CLOSE TO OR A LITTLE ABOVE THE INTENSITY CONSENSUS AFTER 12 HOURS AND IS SIMILAR TO THE PREVIOUS ADVISORY. THE INITIAL MOTION ESTIMATE IS 360/04. THE MID-LEVEL RIDGE NORTH OF LESLIE IS EXPECTED TO WEAKEN DURING THE NEXT DAY OR TWO AS A LONGWAVE TROUGH MOVES INTO EASTERN NORTH AMERICA. LESLIE SHOULD BEGIN TO ACCELERATE NORTHWARD AND THEN NORTH-NORTHEASTWARD THROUGH THE PERIOD AS IT INTERACTS WITH THE TROUGH. THE NHC TRACK FORECAST THROUGH 48 HOURS IS LARGELY AN UPDATE OF THE PREVIOUS ONE AND IS NEAR THE MIDDLE OF THE GUIDANCE ENVELOPE. AT 72 HOURS AND BEYOND... THE NHC FORECAST HAS BEEN SHIFTED TO THE LEFT WITH A SLIGHTLY SLOWER FORWARD SPEED. THIS REPRESENTS A TREND TOWARD THE LATEST TRACK GUIDANCE...WHICH FOR THIS CYCLE GENERALLY SHOWS MORE INTERACTION BETWEEN LESLIE AND A SHORTWAVE TROUGH THAT TRIES TO CUT OFF EAST OF NEW ENGLAND IN 3 TO 4 DAYS. HOWEVER...THE NEW NHC TRACK IS STILL A LITTLE EAST OF THE TVCA CONSENSUS AND LIES ALONG THE EASTERN EDGE OF THE GUIDANCE ENVELOPE LATE IN THE PERIOD. 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 AND INTO EARLY NEXT WEEK. FORECAST POSITIONS AND MAX WINDS INIT 08/0900Z 28.1N 62.3W 55 KT 65 MPH 12H 08/1800Z 28.9N 62.2W 55 KT 65 MPH 24H 09/0600Z 30.3N 62.0W 60 KT 70 MPH 36H 09/1800Z 31.9N 61.6W 65 KT 75 MPH 48H 10/0600Z 33.6N 61.0W 75 KT 85 MPH 72H 11/0600Z 38.5N 58.5W 80 KT 90 MPH 96H 12/0600Z 44.5N 55.5W 65 KT 75 MPH...POST-TROP/EXTRATROP 120H 13/0600Z 48.0N 53.0W 55 KT 65 MPH...POST-TROP/EXTRATROP $$ FORECASTER BRENNAN