Tropical Storm NICHOLAS

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TROPICAL STORM NICHOLAS DISCUSSION NUMBER  22
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT SAT OCT 18 2003
 
NICHOLAS CONTINUES TO STRUGGLE UNDER THE RELENTLES SOUTHWESTERLY
SHEAR. T-NUMBERS CONTINUE TO DECREASE AND THE INITIAL INTENSITY IS
LOWERED TO 45 KTS.

THE SYSTEM SEEMS TO HAVE BEEN WANDERING FOR MUCH OF THE DAY AND HAS
DRIFTED BACK TOWARD THE WEST IN THE PAST 6 HOURS.  THE MOTION FOR
THE PAST 12 TO 18 HOURS HAS BEEN 340/2...A SLOW DRIFT TOWARD THE
NORTH-NORTHWEST...AND THAT WILL BE THE INITIAL MOTION.

INFRARED SATELLITE IMAGERY SHOWS THE APPROACH OF A PARTICULARLY
STRONG PULSE OF MID- TO UPPER-LEVEL SOUTHWESTERLY WINDS. THIS WILL
SEVERELY DISRUPT THE UPPER-LEVEL STRUCTURE AND WILL PROBABLY BEGIN
THE DEMISE OF THE SYSTEM.  AS THE UPPER-LEVEL IS SHEARED AWAY THE
STEERING WILL BE CONTROLLED MORE BY THE MID- TO LOW-LEVEL FLOW.  THE
BAM SHALLOW AND MEDIUM SUGGEST A MORE WEST-NORTHWEST TO NORTHWEST
TRACK AND ARE IN GOOD AGREEMENT WITH THE GFS WHICH WANTS TO WEAKEN
THE SYSTEM AND MOVE IT WITH THE LOW LEVEL FLOW.  MOST OF THE OTHER
GLOBAL MODELS INITIALLY MOVE THE SYSTEM NORTH-NORTHWEST.  THE
GFDL...NOGAPS AND UKMET ALSO WANT TO ACCELERATE THE SYSTEM TOWARD
THE NORTH OR NORTH-NORTHEAST IN THE 72 TO 96 HOUR TIME FRAME IN
RESPONSE TO A SHORT WAVE IN THE WESTERLIES.  THESE MODELS ARE
ASSUMING A DEEP-CONVECTIVE SYSTEM WHICH...IN ALL LIKELYHOOD...WILL
NOT EXIST.  

THE OFFICIAL FORECAST IS AN UPDATE OF THE PREVIOUS FORECAST BUT A
SLOWER INITIAL MOTION AND SLOWER SPEEDS IN THE EARLY FORECAST
POSITIONS.

THE INTENSITY FORECAST FOLLOWS THE SHIPS GUIDANCE WHICH FORECASTS
HIGH SHEAR VALUES OVER THE SYSTEM THROUGHOUT THE FORECAST PERIOD. 

FORECASTER JARVINEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      19/0300Z 17.3N  48.2W    45 KT
 12HR VT     19/1200Z 17.4N  48.4W    40 KT
 24HR VT     20/0000Z 17.9N  48.8W    35 KT
 36HR VT     20/1200Z 18.5N  49.3W    35 KT
 48HR VT     21/0000Z 19.4N  49.9W    30 KT
 72HR VT     22/0000Z 21.1N  51.4W    30 KT
 96HR VT     23/0000Z 23.1N  52.7W    30 KT
120HR VT     24/0000Z 25.2N  53.6W    25 KT
 
 
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