000 WTNT42 KNHC 062037 TCDAT2 HURRICANE LESLIE DISCUSSION NUMBER 30 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122012 500 PM AST THU SEP 06 2012 THERE HAS NOT BEEN A SIGNIFICANT CHANGE IN THE SATELLITE PRESENTATION DURING THE DAY WITH THE EXCEPTION THAT THE OVERALL CLOUD PATTERN IS A LITTLE SMALLER. THERE IS A CONVECTIVE BAND WRAPPING AROUND A SMALL CENTRAL DENSE OVERCAST...WHICH GIVES THE APPEARANCE OF BETTER ORGANIZATION. HOWEVER...MICROWAVE DATA DOES NOT SHOW A WELL-DEFINED INNER CORE AT THIS TIME. DVORAK T-NUMBERS FROM BOTH TAFB AND SAB SUPPORT KEEPING AN INITIAL INTENSITY OF 65 KNOTS. SINCE LESLIE HAS BEEN MOVING LITTLE...IT IS PRODUCING UPWELLING RESULTING IN LOWER SEA SURFACE TEMPERATURES IN THE AREA. THE UPWELLING IN COMBINATION WITH THE SHEAR WOULD NOT FAVOR ANY SIGNIFICANT STRENGTHENING UNTIL LESLIE BEGINS TO MOVE NORTHWARD OVER UNDISTURBED WARMER WATERS IN A DAY OR TWO. THE NHC FORECAST CALLS FOR A MODEST STRENGTHENING BEGINNING IN 24 HOURS. LESLIE CONTINUES TO BE EMBEDDED WITHIN VERY LIGHT STEERING CURRENTS...AND CONSEQUENTLY IT HAS REMAINED PRACTICALLY STATIONARY ALL DAY. THERE ARE NO INDICATIONS FROM GLOBAL MODELS OR OTHER GUIDANCE THAT LESLIE WILL BEGIN TO MOVE FASTER ANY TIME SOON. IN FACT...THE NHC FORECAST MOVES LESLIE NORTHWARD ONLY 120 NAUTICAL MILES IN TWO DAYS. BEYOND 48 HOURS...THE SUBTROPICAL RIDGE IS FORECAST TO BUILD TO THE EAST OF LESLIE...AND THIS FEATURE IN COMBINATION WITH AN APPROACHING MID-LEVEL TROUGH WILL FORCE THE HURRICANE ON A NORTHWARD TRACK...AND THEN NORTHEASTWARD WITH A GRADUAL INCREASE IN FORWARD SPEED. THE NHC FORECAST CONTINUES TO BE VERY CLOSE TO THE CONSENSUS AND BETWEEN THE GFS AND THE ECMWF GLOBAL MODELS. IT IS INTERESTING TO NOTE THAT THE WHOLE GUIDANCE ENVELOPE SHIFTED A LITTLE BIT EASTWARD AWAY FROM BERMUDA THIS AFTERNOON...BUT THE NHC FORECAST PREFERS TO MAKE THAT EASTWARD ADJUSTMENT MORE GRADUALLY. 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 06/2100Z 26.5N 62.2W 65 KT 75 MPH 12H 07/0600Z 26.6N 62.2W 65 KT 75 MPH 24H 07/1800Z 27.0N 62.4W 70 KT 80 MPH 36H 08/0600Z 27.5N 62.5W 75 KT 85 MPH 48H 08/1800Z 28.5N 62.6W 85 KT 100 MPH 72H 09/1800Z 32.0N 62.2W 90 KT 105 MPH 96H 10/1800Z 35.5N 60.0W 80 KT 90 MPH 120H 11/1800Z 41.5N 56.0W 70 KT 80 MPH $$ FORECASTER AVILA