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TROPICAL STORM LORENZO DISCUSSION NUMBER  11
NATIONAL WEATHER SERVICE MIAMI FL
10 PM EST MON OCT 29 2001
 
TROPICAL DEPRESSION FIFTEEN HAS BEEN UPGRADED TO TROPICAL STORM 
LORENZO BASED ON DVORAK INTENSITY ESTIMATES OF 30 KT FROM TAFB AND 
AFWA...AND 35 KT FROM SAB. HOWEVER...AFWA REPORTED A DATA-T NUMBER 
OF 3.0...45 KT...AND DEEP CONVECTION HAS DEVELOPED OVER THE CENTER 
AND CONVECTIVE BANDING HAS ALSO IMPROVED SINCE THE 30/00Z SATELLITE 
ANALYSES.  ALSO...EARLIER TODAY...SEVERAL SHIPS REPORTED THE HIGHEST 
WINDS OF 30 KT WELL TO THE SOUTHEAST OUTSIDE OF DEEP CONVECTION...SO 
TAKING THE CYCLONE UP TO 35 KT SEEMS REASONABLE. UPPER-LEVEL OUTFLOW 
IS FAIR TO THE NORTH AND IMPROVING AS THE SOUTHWESTERLY SHEAR HAS 
DECREASED.

THE INITIAL MOTION ESTIMATE IS 300/09.  THERE IS NO SIGNIFICANT 
CHANGE TO THE PREVIOUS FORECAST TRACK OR REASONING. WATER VAPOR 
IMAGERY INDICATES THAT LORENZO IS BEGINNING TO BECOME INFLUENCED BY 
THE APPROACHING TROUGH TO THE WEST AND GRADUAL RECURVATURE SHOULD 
BEGIN IN ABOUT 12 TO 18 HOURS. THE OFFICIAL FORECAST IS SIMILAR TO 
THE PREVIOUS FORECAST TRACK AND IS CLOSE TO THE AVN SOLUTION.
 
NOW THAT THE UPPER-LEVEL SHEAR HAS WEAKENED...SOME ADDITIONAL 
STRENGTHENING IS POSSIBLE FOR ANOTHER 24 TO 36 HOURS BEFORE 
INCREASING SOUTHWESTERLY SHEAR OF MORE THAN 40 KT KICKS IN AND 
DECAPITATES LORENZO. THE CYCLONE IS EXPECTED BECOME ABSORBED BY 
AN EXTRATROPICAL LOW ASSOCIATED WITH THE APPROACHING COLD FRONT 
AND UPPER-LEVEL TROUGH.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     30/0300Z 28.7N  45.0W    35 KTS
12HR VT     30/1200Z 30.3N  45.9W    35 KTS
24HR VT     31/0000Z 32.9N  45.4W    40 KTS
36HR VT     31/1200Z 36.3N  42.5W    45 KTS
48HR VT     01/0000Z 41.0N  38.0W    35 KTS...BECOMING EXTRATROPICAL
72HR VT     02/0000Z...ABSORBED BY FRONTAL SYSTEM
 
 
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