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HURRICANE ALBERTO DISCUSSION NUMBER  36
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT SAT AUG 12 2000
 
HURRICANE ALBERTO HAS RAPIDLY WEAKENED DURING THE PAST 6 HOURS AS
THE CYCLONE HAS EXPERIENCED INCREASING WESTERLY SHEAR. THE INITIAL
INTENSITY OF 100 KT IS BASED ON 00Z SATELLITE INTENSITY ESTIMATES OF
95 AND 100 KT FROM SAB AND TAFB...RESPECTIVELY...AND ALSO A RAGGED
CLOUD-FILLED EYE IN RECENT SATELLITE IMAGERY. OUTFLOW REMAINS GOOD
IN THE EAST SEMICIRCLE...FAIR TO THE SOUTHWEST AND RESTRICTED TO THE
NORTHWEST.

THE OFFICIAL FORECAST TRACK IS A LITTLE SOUTH OF THE PREVIOUS TRACK
THOUGH 36 HOURS..AND A LITTLE EAST AFTERWARDS. ALL OF THE FORECAST
MODEL TRACKS ARE A LITTLE FURTHER EAST THAN PREVIOUS RUNS...POSSIBLY
DUE TO MORE LOW- AND MID-LEVEL STEERING AS THE UPPER-LEVEL
CIRCULATION DECOUPLES FROM THE LOW-LEVEL CENTER DUE TO EXPECTED
WEAKENING CONVECTION. THE UPPER-TROPOSPHERIC LOW CURRENTLY SOUTH OF
THE AZORES AS SEEN IN WATER VAPOR IMAGERY IS FORECAST BY THE AVN
MODEL TO GRADUALLY FILL AND LIFT OUT TO THE NORTHEAST ACROSS THE
AZORES AFTER 36 HOURS...LEAVING BEHIND A BROAD WEAK TROUGH. THE
SURFACE TO 700 MB SUBTROPICAL RIDGE TO THE SOUTH IS FORECAST TO
REMAIN INTACT...WHICH MAY ACT TO KEEP ALBERTO ON A MORE EASTERLY
TRACK TOWARD THE AZORES BY THE END OF THE FORECAST PERIOD.
 
WESTERLY SHEAR IS EXPECTED TO INCREASE DUE TO THE SMALL BLOCKING
PATTERN TO THE EAST. COMBINE THE SHEAR WITH PROGRESSIVELY COOLER
SSTS...25C TO 23C...AND THE INGREDIENTS ARE THERE FOR STEADY AND
POSSIBLE RAPID WEAKENING. THE SHIPS INTENSITY MODEL TAKES ALBERTO
DOWN BELOW TROPICAL DEPRESSION INTENSITY BY 72 HOURS...BUT WE HAVE
KEPT THE INTENSITY HIGHER DUE TO EXPECTED EXTRATROPICAL TRANSITION.

FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     13/0300Z 37.8N  51.0W   100 KTS
12HR VT     13/1200Z 38.7N  48.1W    85 KTS
24HR VT     14/0000Z 39.3N  44.2W    75 KTS
36HR VT     14/1200Z 39.3N  41.0W    65 KTS...BECOMING EXTRATROPICAL
48HR VT     15/0000Z 39.0N  38.0W    60 KTS...EXTRATROPICAL
72HR VT     16/0000Z 36.8N  34.8W    55 KTS...EXTRATROPICAL
 
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