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HURRICANE ALBERTO DISCUSSION NUMBER  18
NATIONAL WEATHER SERVICE MIAMI FL
11 AM AST TUE AUG 08 2000
 
THE APPEARANCE OF ALBERTO REMAINS RATHER RAGGED DUE TO SOUTHERLY
VERTICAL SHEAR.  HOWEVER...THE CENTRAL CONVECTION HAS INCREASED
SOMEWHAT OVER THE PAST FEW HOURS AND SATELLITE INTENSITY ESTIMATES
ARE UNCHANGED FROM 6 HR AGO.  THE MAXIMUM WINDS WILL REMAIN 70 KT
FOR THIS PACKAGE.

ALBERTO CONTINUES ITS STAIR-STEPPING WAYS AND THE INITIAL MOTION IS
NOW 285/11.  THE HURRICANE IS MOVING THROUGH AN UPPER LEVEL TROUGH
WHILE A STRONG LOW/MID LEVEL RIDGE CONTINUES NORTH OF THE CYCLONE. 
NHC TRACK MODEL GUIDANCE CONTINUES TO INDICATE A NORTHWEST TRACK...
WHICH IS AT ABOUT A 30-40 DEGREE ANGLE TO HOW ALBERTO HAS BEEN
MOVING.  THE OFFICIAL FORECAST CALLS FOR A CONTINUED WEST-NORTHWEST
MOTION THROUGH 72 HR AND IS ALONG THE LEFT EDGE OF THE GUIDANCE. 
ALBERTO IS LIKELY TO CONTINUE STAIR-STEPPING...WOBBLING TO THE RIGHT
AND LEFT OF THE FORECAST TRACK.

LARGE-SCALE MODELS ARE IN UNANIMOUS AGREEMENT THAT THE UPPER LEVEL
TROUGH WILL SPLIT BY 48 HR AND LEAVE ALBERTO IN A MORE FAVORABLE
ENVIRONMENT.  WHILE NOT CONCLUSIVE...WATER VAPOR IMAGERY SUGGESTS
THIS FORECAST COULD VERIFY.  THE GFDU AND SHIP MODELS RESPOND TO THE
TROUGH SPLIT BY INTENSIFYING ALBERTO AFTER 36 HR...AND THE INTENSITY
FORECAST REFLECTS THIS.  IN THE SHORT TERM...THERE COULD BE MORE
WEAKENING WHILE THE SHEAR CONTINUES...WHICH IS ALSO REFLECTED IN THE
FORECAST.
 
FORECASTER BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     08/1500Z 17.4N  45.9W    70 KTS
12HR VT     09/0000Z 17.9N  47.6W    65 KTS
24HR VT     09/1200Z 18.7N  49.8W    65 KTS
36HR VT     10/0000Z 19.7N  51.8W    65 KTS
48HR VT     10/1200Z 21.0N  54.0W    70 KTS
72HR VT     11/1200Z 23.0N  59.0W    80 KTS
 
 
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