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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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