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| #540760 (Received by flhurricane at: 4:32 PM 06.Sep.2012) TCDAT3 HURRICANE MICHAEL DISCUSSION NUMBER 15 NWS NATIONAL HURRICANE CENTER MIAMI FL AL132012 500 PM AST THU SEP 06 2012 RECENT MICROWAVE AND ENHANCED BD-CURVE INFRARED IMAGERY INDICATE SOME WEAKENING OF THE INNER CORE...PARTICULARLY IN THE SOUTHWEST QUADRANT. CONSEQUENTLY...THE FINAL SUBJECTIVE DVORAK INTENSITY ESTIMATES FROM BOTH AGENCIES HAVE DECREASED TO 77 KT. HOWEVER...THE INITIAL INTENSITY HAS BEEN LOWERED JUST A BIT TO 95 KT IN CONSIDERATION OF THE 105 KT UW-CIMSS ADT ESTIMATE. GRADUAL WEAKENING THROUGH THE ENTIRE PERIOD IS REFLECTED IN THE OFFICIAL INTENSITY FORECAST...PRIMARILY DUE TO EITHER A MID- TO UPPER-LEVEL MID-LATITUDE TROUGH APPROACHING FROM THE NORTHWEST...OR THE LARGE OUTFLOW ASSOCIATED WITH HURRICANE LESLIE. THE NHC INTENSITY FORECAST CALLS FOR GRADUAL WEAKENING THROUGH 5 DAYS AND IS A COMPROMISE BETWEEN THE IVCN CONSENSUS AND THE FLORIDA STATE UNIVERSITY SUPERENSEMBLE. THE INITIAL MOTION ESTIMATE IS 020/6...WITH A TURN TO THE NORTH AND THE NORTH-NORTHWEST OCCURRING DURING THE NEXT 24 HOURS. THE GLOBAL AND HURRICANE MODELS HAVE BECOME MUCH MORE ALIGNED WITH A SIMILAR NORTH-NORTHWESTWARD TO NORTHWESTWARD MOTION...ALBEIT WITH SIGNIFICANT FORWARD SPEED DIFFERENCES BEYOND 48 HOURS. THE GUIDANCE NOW APPEARS TO BE RESPONDING MORE TO A STEERING ENVIRONMENT PRODUCED BY A SIGNIFICANT BREAK IN THE SUBTROPICAL RIDGE NEAR 45W AND THE AZORES HIGH ANCHORED TO THE EAST. THE GFS AND THE GFDL MODELS ARE QUITE A BIT FASTER BEYOND DAY 4 WHILE THE REMAINING AVAILABLE GUIDANCE AGREE MORE ON A SLOWER 5-7 KT FORWARD MOTION. THE NHC FORECAST IS VERY CLOSE TO THE PAST 6 HOUR TRACK FORECAST...BUT A LITTLE FASTER AT DAY 5 IN ORDER TO HEDGE CLOSER TO THE TVCA CONSENSUS WHICH INCORPORATES THE FASTER GFDL AND GFS. FORECAST POSITIONS AND MAX WINDS INIT 06/2100Z 30.6N 41.0W 95 KT 110 MPH 12H 07/0600Z 31.1N 41.0W 90 KT 105 MPH 24H 07/1800Z 31.7N 41.5W 85 KT 100 MPH 36H 08/0600Z 32.2N 42.1W 80 KT 90 MPH 48H 08/1800Z 32.8N 42.6W 80 KT 90 MPH 72H 09/1800Z 34.0N 43.5W 75 KT 85 MPH 96H 10/1800Z 36.2N 45.3W 70 KT 80 MPH 120H 11/1800Z 40.0N 46.5W 60 KT 70 MPH $$ FORECASTER ROBERTS |
