Hurricane MICHAEL

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HURRICANE MICHAEL DISCUSSION NUMBER  31
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL132012
500 PM AST MON SEP 10 2012
 
THE EYE OF MICHAEL HAS BECOME OBSCURED AND MORE RAGGED DURING THE
PAST SEVERAL HOURS.  NORTHERLY SHEAR MAY BE INCREASING AS EVIDENCED
BY THE APPROACH OF A CIRRUS CLOUD SHIELD FROM THE WEST ASSOCIATED
WITH OUTFLOW OF LESLIE.  THE CLOUD PATTERN HAS BECOME MORE
ASYMMETRIC AS A RESULT OF THE INCREASE IN SHEAR...WITH THE BULK OF
THE CLOUDINESS AND DEEP CONVECTION IN THE SOUTHERN SEMICIRCLE.  A
BLEND OF THE LATEST DVORAK T- AND CI-NUMBERS...AS WELL AS RECENT
ADT CI VALUES...SUGGESTS THAT MICHAEL HAS WEAKENED. THE INITIAL
INTENSITY ESTIMATE IS LOWERED TO 65 KT...IN LINE WITH THESE DATA. 
NORTH-NORTHEASTERLY SHEAR AND DECREASING SEA SURFACE TEMPERATURES
ARE EXPECTED TO TAKE A TOLL ON MICHAEL DURING THE NEXT 24 TO 36
HOURS.  AS A RESULT...CONTINUED WEAKENING IS LIKELY PRIOR TO THE
CYCLONE BECOMING A FRONTAL WAVE JUST BEFORE 48 HOURS. POST-TROPICAL
MICHAEL IS FORECAST TO BE ABSORBED BY A FRONTAL SYSTEM BY 72 HOURS. 
THE NHC INTENSITY FORECAST IS REDUCED SLIGHTLY FROM THE PREVIOUS
ONE AND IS WEIGHTED TOWARD THE BETTER PERFORMING INTENSITY
CONSENSUS AIDS.
 
THE HEADING OF MICHAEL HAS BEGUN TO QUICKLY SHIFT TOWARD THE RIGHT
AND THE FORWARD SPEED HAS INCREASED SINCE THE LAST ADVISORY.  BASED
ON THE RECENT CENTER FIXES...THE INITIAL MOTION ESTIMATE IS 305/10.
MICHAEL IS ROUNDING THE SOUTHWESTERN PERIPHERY OF A MID-LEVEL HIGH
CENTERED NEAR 39N 45W...AND A TURN TOWARD THE NORTH-NORTHWEST AND
THEN THE NORTH WITH A FURTHER INCREASE IN FORWARD SPEED SHOULD OCCUR
WITHIN 24 HOURS.  AN ACCELERATION TOWARD THE NORTH-NORTHEAST
IS EXPECTED AFTER THAT AS MICHAEL BECOMES EMBEDDED IN A FAST-PACED
FLOW IN BETWEEN THE RIDGE TO ITS EAST AND A RAPIDLY ADVANCING
SHORTWAVE OVER THE CANADIAN MARITIMES.  THE NHC TRACK FORECAST IS
ESSENTIALLY AN UPDATE OF THE PREVIOUS ONE AND LIES IN BETWEEN THE
GFS AND ECMWF MODELS...VERY NEAR THE MULTI-MODEL TVCA CONSENSUS.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  10/2100Z 34.4N  47.6W   65 KT  75 MPH
 12H  11/0600Z 36.2N  48.3W   55 KT  65 MPH
 24H  11/1800Z 39.8N  47.7W   45 KT  50 MPH
 36H  12/0600Z 44.2N  44.8W   40 KT  45 MPH
 48H  12/1800Z 49.6N  38.5W   35 KT  40 MPH...POST-TROP/EXTRATROP
 72H  13/1800Z...ABOSORBED BY A FRONT
 
$$
FORECASTER KIMBERLAIN
 
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