000 WTNT42 KNHC 060240 TCDAT2 HURRICANE LESLIE DISCUSSION NUMBER 27 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122012 1100 PM AST WED SEP 05 2012 RECENT TRMM AND SSMI MICROWAVE IMAGES INDICATE THAT LESLIE HAS NOT FORMED A CLOSED EYEWALL...AND IN FACT...THE INNER CORE CONVECTION HAS BECOME SOMEWHAT RAGGED. THERE IS STILL SOME INDICATION OF WESTERLY SHEAR AS WELL...WITH MOST OF THE CONVECTIVE BANDING LOCATED OVER THE EASTERN SEMICIRCLE. THE INITIAL INTENSITY IS BEING HELD AT 65 KT BASED ON DVORAK ESTIMATES OF T4.0 FROM TAFB AND SAB...AND A UW-CIMSS ADT ESTIMATE OF T3.7/4.3. BASED ON RECENT TRMM MICROWAVE FIXES...THE MOTION IS ESTIMATED TO BE 010/2 KT. LESLIE SHOULD CONTINUE A SLOW NORTHWARD CREEP FOR THE NEXT 48 HOURS OR SO WHILE IT REMAINS TRAPPED TO THE SOUTH OF A MID-LEVEL HIGH CENTERED TO THE NORTHEAST OF BERMUDA. THE HURRICANE SHOULD GAIN SOME NORTHWARD MOMENTUM BY DAY 3 ONCE A DEEP-LAYER TROUGH DEVELOPS OVER THE EASTERN UNITED STATES. THE GFS MODEL HAS SHIFTED BACK TO THE EAST ON THIS CYCLE AND IS THE EASTERNMOST AND SLOWEST OF THE DYNAMICAL GUIDANCE ON DAYS 3 THROUGH 5. SINCE THIS HAS NOT YET TURNED INTO A CONSISTENT TREND...THE NHC FORECAST IS BEING KEPT CLOSER TO THE MIDDLE OF THE GUIDANCE ENVELOPE AND IS VERY SIMILAR TO THE PREVIOUS TRACK FORECAST. LESLIE IS PRECARIOUSLY CLOSE TO DRY AIR LOCATED OVER THE WESTERN ATLANTIC. A CROSS SECTION BASED ON GFS MODEL DATA SHOWS AIR WITH RELATIVE HUMIDITY LESS THAN 30 PERCENT ABUTTING AGAINST THE CIRCULATION IN THE 250-500 MB LAYER. SINCE MODERATE WESTERLY SHEAR IS EXPECTED TO AFFECT LESLIE FOR THE NEXT 24 HOURS OR SO...THE DRY AIR COULD CONTINUE TO SEEP INTO THE CIRCULATION. IN ADDITION... MICROWAVE DATA INDICATES THAT THE SEA SURFACE BENEATH LESLIE IS COOLING DUE TO UPWELLING...AND THIS IS UNLIKELY TO CHANGE AS LONG AS THE HURRICANE MOVES SO SLOWLY. THE NHC INTENSITY FORECAST IS MOSTLY UNCHANGED FROM THE PREVIOUS ONE AND INDICATES GRADUAL STRENGTHENING DURING THE NEXT 3 TO 4 DAYS. LESLIE IS A LARGE TROPICAL CYCLONE THAT IS FORECAST TO GROW IN SIZE OVER THE NEXT SEVERAL DAYS. THE WIND FIELD OF THE CYCLONE... COMBINED WITH ITS EXPECTED SLOW MOTION...WILL HELP TO GENERATE LONG-PERIOD SWELLS THAT WILL PRODUCE LARGE WAVES AND LIFE- THREATENING RIP CURRENTS ON BERMUDA AND MUCH OF THE U.S. EAST COAST FOR THE REMAINDER OF THIS WEEK. FORECAST POSITIONS AND MAX WINDS INIT 06/0300Z 26.2N 62.5W 65 KT 75 MPH 12H 06/1200Z 26.4N 62.6W 70 KT 80 MPH 24H 07/0000Z 26.8N 62.7W 75 KT 85 MPH 36H 07/1200Z 27.1N 63.0W 80 KT 90 MPH 48H 08/0000Z 27.7N 63.4W 85 KT 100 MPH 72H 09/0000Z 30.5N 64.0W 90 KT 105 MPH 96H 10/0000Z 35.5N 63.0W 90 KT 105 MPH 120H 11/0000Z 44.0N 59.5W 75 KT 85 MPH $$ FORECASTER BERG