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TROPICAL STORM ALETTA DISCUSSION NUMBER 5
NATIONAL WEATHER SERVICE MIAMI FL
8 AM PDT TUE MAY 23 2000
EARLY VISIBLE SATELLITE IMAGES INDICATE THAT THE CLOUD PATTERN
ASSOCIATED WITH ALETTA IS GRADUALLY IMPROVING IN ORGANIZATION. AN
AREA OF DEEP CONVECTION HAS DEVELOPED NEAR THE CENTER AND BANDING
FEATURES ARE FORMING. THE OUTFLOW REMAINS FAIR. BECAUSE T-NUMBERS
ARE 2.5 AND 3.0 ON THE DVORAK SCALE...INITIAL INTENSITY IS INCREASED
TO 40 KNOTS AT THIS TIME. SHIPS INTENSITY FORECAST MODEL SUGGESTS
THAT SOME PARAMETERS...SST AND SHEAR...ARE FAVORABLE FOR A GRADUAL
STRENGTHENING DURING THE NEXT DAY OR SO AND THIS IS INDICATED IN THE
OFFICIAL FORECAST.
ALETTA IS STILL IN DEVELOPING STAGE AND THE CENTER IS DIFFICULT TO
LOCATE ON IR IMAGES. BEST ESTIMATE OF THE INITIAL MOTION IS 285/07.
MOST OF THE GUIDANCE SUGGESTS THAT THIS MOTION SHOULD CONTINUE
DURING THE NEXT 24 TO 48 HOURS. THEREAFTER...STEERING CURRENTS ARE
EXPECTED TO COLLAPSE RESULTING IN A LITTLE MOTION OF THE TROPICAL
CYCLONE. IN FACT...GFDL...UK...AND AVN MODELS TAKE A WEAKENING
ALETTA TO THE EAST BY THE END OF THE FORECAST PERIOD. THE OFFICIAL
FORECAST OPTED FOR KEEPING THE TROPICAL CYCLONE ON A WESTWARD TRACK
AND CALLS FOR A DECREASE IN FORWARD SPEED. THIS MOTION WOULD KEEP
ALETTA AWAY FROM THE COAST OF MEXICO.
AVILA
FORECAST POSITIONS AND MAX WINDS
INITIAL 23/1500Z 14.9N 102.8W 40 KTS
12HR VT 24/0000Z 15.1N 103.8W 45 KTS
24HR VT 24/1200Z 15.5N 105.0W 50 KTS
36HR VT 25/0000Z 16.0N 106.0W 55 KTS
48HR VT 25/1200Z 16.3N 107.0W 60 KTS
72HR VT 26/1200Z 16.5N 108.0W 60 KTS
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