Tropical Storm NICHOLAS

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TROPICAL STORM NICHOLAS DISCUSSION NUMBER  14
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT THU OCT 16 2003
 
ALTHOUGH THE CENTER IS IMPOSSIBLE TO LOCATE ON IR OR NIGHT-VIS
IMAGERY...THERE IS EVIDENCE THAT THE NICHOLAS HAS BEEN MOVING TO
THE LEFT OF THE PREVIOUS FORECAST TRACK.  ANALYSIS OF THE 21Z
QUIKSCAT AMBIGUITIES STRONGLY INDICATES THAT THE CENTER IS NOT
UNDERNEATH THE DEEP CONVECTION...BUT RATHER IS NEAR OR BEYOND ITS
SOUTHWEST EDGE.  A MICROWAVE PASS...ALSO AT 21Z...IS CONSISTENT
WITH THIS LOCATION.  IF THIS ANALYSIS IS CORRECT...THEN THE
SOUTHWESTERLY SHEAR IS RE-ASSERTING ITSELF AND NICHOLAS IS NOT AS
WELL ORGANIZED AS IT WAS EARLIER.  THE INITIAL MOTION IS ESTIMATED
TO BE 300/8 AND THE INITIAL INTENSITY IS HELD AT 55 KT.

THE GLOBAL MODELS...PARTICULARLY THE GFS...SUGGEST THAT
SOUTHWESTERLY SHEAR IS GOING TO BE AN ISSUE FOR NICHOLAS OVER THE
NEXT SEVERAL DAYS...AND HOW THE CYCLONE RESPONDS TO THE SHEAR WILL
DETERMINE BOTH THE INTENSITY AND THE TRACK.  THE SHEAR SHOULD BE
LOWEST OVER THE NEXT 48 HOURS...AND SO THE OFFICIAL FORECAST STILL
SHOWS NICHOLAS REACHING HURRICANE STRENGTH.  HOWEVER... TOWARDS THE
END OF THE FORECAST PERIOD STRONGER WESTERLIES ARE LIKELY TO EITHER
TAKE A STRONGER SYSTEM ON A MORE NORTHERLY TRACK...OR LEAVE A
SHEARED SYSTEM BEHIND ON A MORE WESTERLY PATH.  THE FORMER OPTION
IS REPRESENTED BY THE GFDL...WHILE THE LATTER BY THE SHALLOW AND
MEDIUM BAM AND THE GFS.  IT IS QUITE POSSIBLE THAT NICHOLAS WILL
OSCILLATE BETWEEN A WEST-NORTHWEST AND NORTH-NORTHWEST TRACK WITH
SHORT-TERM VARIATIONS IN THE SHEAR AND DEEP CONVECTION.  THE
OFFICIAL FORECAST HAS BEEN ADJUSTED A LITTLE TO THE LEFT OF THE
PREVIOUS TRACK BY VIRTUE OF THE SHIFT IN THE INITIAL POSITION...BUT
IS OTHERWISE SIMILAR.  CONFIDENCE IN THIS FORECAST... ESPECIALLY BY
DAYS 4 AND 5...IS NOT REAL HIGH.
 
FORECASTER FRANKLIN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      17/0300Z 14.5N  47.8W    55 KT
 12HR VT     17/1200Z 15.4N  48.4W    55 KT
 24HR VT     18/0000Z 16.4N  49.1W    60 KT
 36HR VT     18/1200Z 17.2N  50.0W    65 KT
 48HR VT     19/0000Z 18.0N  51.0W    65 KT
 72HR VT     20/0000Z 19.0N  52.0W    60 KT
 96HR VT     21/0000Z 20.0N  53.0W    55 KT
120HR VT     22/0000Z 21.0N  54.0W    55 KT
 
 
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