[NCEP Logo] HOME ARCHIVES FORECASTS IMAGERY ABOUT TPC RECONNAISSANCE

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TROPICAL STORM MANUEL DISCUSSION NUMBER  17
NATIONAL WEATHER SERVICE MIAMI FL
2 PM PDT SUN OCT 14 2001

BASED ON RECENT VISIBLE IMAGES...THE CENTER HAS BEEN RE-LOCATED A 
BIT TO THE NORTHEAST OF PREVIOUS POSITION ESTIMATES.  THIS IS NEAR 
THE WESTERN EDGE OF A RAGGED-LOOKING AREA OF DEEP CONVECTION.  THE 
SYSTEM HAS A BROKEN CURVED BAND FEATURE OVER ITS EASTERN 
SEMICIRCLE...AND IS BEING IMPACTED BY WESTERLY SHEAR.  SATELLITE 
IMAGES SUGGEST THAT THE UPPER-LEVEL TROUGH THAT IS PRODUCTING THE 
SHEAR IS BEGINNING TO CUT OFF...AND THE NCEP GLOBAL MODEL INDICATES 
THAT THIS SYSTEM WILL GRADUALLY MOVE TO THE SOUTHWEST AND WEAKEN.  
THIS EVOLUTION TYPICALLY REDUCES THE SHEAR AND PROVIDES A MORE 
FAVORABLE ENVIRONMENT FOR A TROPICAL CYCLONE TO STRENGTHEN.  HOWEVER 
THE GLOBAL MODEL INDICATES THAT A CYCLONIC SHEAR AXIS WILL LINGER IN 
THE VICINITY OF MANUEL EVEN AFTER THE UPPER LEVEL CYCLONE MOVES AWAY 
FROM THE TROPICAL CYCLONE.  ALSO THE TRACK OF MANUEL IS EXPECTED TO 
BE OVER COOLER WATERS NEAR THE END OF THE PERIOD.   THEREFORE THE 
AMOUNT OF FORECAST STRENGTHENING HAS BEEN REDUCED A BIT FROM THE 
PREVIOUS ADVISORIES.

THE CENTER HAS APPARENTLY BEEN MEANDERING SO INITIAL MOTION ESTIMATE 
IS STATIONARY.  MANUEL APPEARS TO HAVE BEEN EMBEDDED IN A BROAD 
MID-LEVEL TROUGH OR WEAKNESS BETWEEN TWO ANTICYCLONES.  THE AVN 
MODEL GRADUALLY BUILDS A 500 MB ANTICYCLONE TO THE NORTHEAST OF 
MANUEL...AND THIS SHOULD INDUCE A NORTHWESTWARD MOTION.  THE 
OFFICIAL FORECAST FOLLOWS THIS REASONING.
 
FORECASTER PASCH
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     14/2100Z 14.4N 113.9W    35 KTS
12HR VT     15/0600Z 15.0N 114.5W    40 KTS
24HR VT     15/1800Z 15.8N 115.5W    45 KTS
36HR VT     16/0600Z 16.5N 116.5W    50 KTS
48HR VT     16/1800Z 17.5N 118.0W    55 KTS
72HR VT     17/1800Z 20.0N 120.5W    55 KTS
 
 
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