000
WTNT43 KNHC 062031
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