000
WTNT43 KNHC 080244
TCDAT3
 
HURRICANE MICHAEL DISCUSSION NUMBER  20
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL132012
1100 PM AST FRI SEP 07 2012
 
THE CLOUD PATTERN OF MICHAEL IN INFRARED IMAGERY HAS CONTINUED TO
DEGRADE DURING THE PAST FEW HOURS...AND RECENT MICROWAVE DATA
INDICATE THAT THE RING OF DEEP CONVECTION AROUND THE CENTER IS OPEN
ON THE WEST SIDE.  THE LATEST SUBJECTIVE DVORAK NUMBERS ARE T4.0/5.0
FROM BOTH TAFB AND SAB AND HAVE FALLEN TO T4.4/4.8 FROM THE
UW-CIMSS ADT.  THE INTENSITY IS THEREFORE LOWERED TO 85 KT.
 
MICHAEL APPEARS TO HAVE BEEN SQUEEZED A BIT FROM THE NORTHWEST AND
SOUTHEAST BY THE SURROUNDING UPPER-LEVEL FLOW...WHICH COULD BE
CONTRIBUTING TO THE SLIGHT WEAKENING.  HOWEVER...THE DEEP-LAYER
SHEAR IS EXPECTED TO BE LIGHT FOR THE NEXT 36 HOURS...AND MICHAEL
IS NOT FORECAST TO CHANGE MUCH IN INTENSITY DURING THAT TIME.  THE
OUTFLOW FROM LESLIE SHOULD PRODUCE STRONG NORTHERLY SHEAR ON THE
ORDER OF 30-40 KT NEAR THE CYCLONE IN ABOUT 3 DAYS...AND MICHAEL IS
EXPECTED TO SUFFER MARKEDLY GIVEN ITS SMALL SIZE.  THE GLOBAL
MODELS THEN SHOW MICHAEL RUNNING INTO A WARM FRONT BY DAY 4...WHILE
OVER SEA SURFACE TEMPERATURES LESS THAN 20 DEGREES CELSIUS...SO THE
CYCLONE IS FORECAST TO BE POST-TROPICAL AT 96 HOURS AND ABSORBED BY
THE FRONT AT 120 HOURS.
 
THE INITIAL MOTION ESTIMATE IS 310/4 KT.  MICHAEL WILL CONTINUE TO
MOVE SLOWLY NORTHWESTWARD DURING THE NEXT 48-72 HOURS WHILE BEING
TRAPPED BETWEEN A RIDGE TO ITS EAST AND A DEVELOPING RIDGE TO ITS
NORTH.  AFTER 72 HOURS...THE CYCLONE WILL BECOME EMBEDDED IN THE
SOUTHERLY FLOW TO THE EAST OF LESLIE...AND IT IS FORECAST TO
ACCELERATE NORTHWARD UNTIL IT BECOMES ABSORBED WITHIN THE FRONTAL
ZONE.  THE TRACK MODELS ARE IN GENERALLY CLOSE PROXIMITY TO EACH
OTHER DURING THE FORECAST PERIOD...AND THE ONLY REAL UPDATE NEEDED
TO THE FORECAST WAS A SLIGHT SOUTHWESTWARD SHIFT OF THE 72-HOUR
POINT.

FORECAST POSITIONS AND MAX WINDS
 
INIT  08/0300Z 31.8N  41.8W   85 KT 100 MPH
 12H  08/1200Z 32.2N  42.1W   80 KT  90 MPH
 24H  09/0000Z 32.9N  42.5W   80 KT  90 MPH
 36H  09/1200Z 33.5N  43.0W   80 KT  90 MPH
 48H  10/0000Z 33.9N  43.8W   75 KT  85 MPH
 72H  11/0000Z 36.0N  46.5W   60 KT  70 MPH
 96H  12/0000Z 44.0N  47.0W   55 KT  65 MPH...POST-TROPICAL
120H  13/0000Z...ABSORBED BY A FRONT
 
$$
FORECASTER BERG