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| #541693 (Received by flhurricane at: 11:02 PM 09.Sep.2012) TCDAT3 HURRICANE MICHAEL DISCUSSION NUMBER 28 NWS NATIONAL HURRICANE CENTER MIAMI FL AL132012 1100 PM AST SUN SEP 09 2012 THE ENHANCED INFRARED SATELLITE PRESENTATION THIS EVENING INDICATES SIGNIFICANT WEAKENING OF THE INNER CORE OF MICHAEL...WITH AN OPENING OF THE EYE WALL IN THE NORTHWEST QUADRANT. IT APPEARS THAT THE MUCH ANTICIPATED INCREASING NORTHERLY SHEAR IS FINALLY BEGINNING TO AFFECT THE CYCLONE. A BLEND OF THE SUBJECTIVE AND OBJECTIVE SATELLITE INTENSITY ESTIMATES SUPPORTS LOWERING THE INITIAL INTENSITY TO 75 KT. THE NORTHERLY SHEAR...PRIMARILY ASSOCIATED WITH THE OUTFLOW OF TROPICAL STORM LESLIE...SHOULD CONTINUE TO IMPACT THE CLOUD PATTERN DURING THE NEXT 24-36 HOURS. AFTER THAT TIME...INCREASING SOUTHWESTERLY SHEAR DOWNSTREAM FROM A DEEP-LAYER BAROCLINIC SYSTEM AND COOLER SEAS SURFACE TEMPERATURES SHOULD CAUSE THE CYCLONE TO WEAKEN SUBSTANTIALLY. SUBSEQUENTLY... MICHAEL IS FORECAST TO LOSE SUFFICIENT TROPICAL CHARACTERISTICS AND BECOME A POST-TROPICAL CYCLONE IN 48 HOURS...THEN TRANSITION TO AN EXTRA-TROPICAL CYCLONE IN 72 HOURS. MICHAEL SHOULD ULTIMATELY BECOME ABSORBED BY A FRONTAL SYSTEM AROUND DAY 4...OR EARLIER. THE NHC INTENSITY FORECAST IS BASICALLY AN UPDATE OF THE PREVIOUS ADVISORY AND IS BASED ON THE IVCN MODEL CONSENSUS. THE INITIAL MOTION IS 265/5. A MID-LEVEL RIDGE LOCATED NORTH OF THE CYCLONE SHOULD KEEP IT ON A GENERAL WESTWARD MOTION DURING THE NEXT 12 HOURS OR SO. AFTERWARD...THE LARGE-SCALE MODELS SHOW MICHAEL TURNING NORTHWESTWARD THEN NORTH-NORTHWESTWARD IN THE WESTERN PERIPHERY OF THE AFOREMENTIONED EASTWARD-MOVING SHORTWAVE RIDGE. BEYOND 36 HOURS...A TURN TOWARD THE NORTH-NORTHEAST AND A SIGNIFICANT INCREASE IN FORWARD SPEED IS FORECAST IN RESPONSE TO A MID- TO UPPER-LEVEL TROUGH APPROACHING FROM THE ATLANTIC CANADIAN MARITIMES. THE OFFICIAL TRACK FORECAST IS A LITTLE TO THE LEFT OF THE PREVIOUS ONE AND IS HEDGED TOWARD THE TVCA CONSENSUS AND THE FLORIDA STATE SUPER ENSEMBLE. FORECAST POSITIONS AND MAX WINDS INIT 10/0300Z 33.6N 44.4W 75 KT 85 MPH 12H 10/1200Z 33.8N 45.6W 70 KT 80 MPH 24H 11/0000Z 34.8N 47.2W 60 KT 70 MPH 36H 11/1200Z 37.3N 48.1W 50 KT 60 MPH 48H 12/0000Z 40.9N 46.9W 45 KT 50 MPH...POST-TROPICAL 72H 13/0000Z 48.0N 40.0W 35 KT 40 MPH...POST-TROP/EXTRATROP 96H 14/0000Z...ABSORBED BY A FRONT $$ FORECASTER ROBERTS |
