Tropical Storm ISIS

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TROPICAL STORM ISIS DISCUSSION NUMBER  26
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
8 AM PDT TUE SEP 14 2004
 
INFRARED IMAGERY SHOWS THAT ISIS HAS BECOME BETTER ORGANIZED THIS
MORNING...WITH A HEALTHY CONVECTIVE BAND WRAPPING AROUND THE
WESTERN SEMICIRCLE.  SATELLITE INTENSITY ESTIMATES ARE 55 KT FROM
TAFB...45 KT FROM SAB...AND 35 KT FROM AFWA.  THE INITIAL INTENSITY
REMAINS 45 KT FOR THIS PACKAGE.  THE SHEAR IS CURRENTLY LIGHT AND
ISIS IS SHOWING POOR TO FAIR OUTFLOW IN ALL DIRECTIONS.

THE INITIAL MOTION IS A RATHER UNCERTAIN 280/5.  ISIS IS SOUTH OF
LOW/MID-LEVEL RIDGE AND A DEVELOPING WEAKNESS IN A MID/UPPER-LEVEL
RIDGE TO THE NORTH.  LARGE-SCALE MODELS FORECAST THIS WEAKNESS TO
PERSIST...WHICH SHOULD PRODUCE A SLOW MOTION FOR THE NEXT 5 DAYS. 
TRACK FORECAST GUIDANCE IS IN GOOD AGREEMENT ON A SLOW
WEST-NORTHWESTWARD MOTION FOR THE FIRST 48 HR...THEN SPREADS OUT
SIGNIFICANTLY WITH FORECAST TRACKS EVERYWHERE FROM WEST THROUGH
NORTH THROUGH EAST.  THIS GENERALLY MEANS THE MOTION WILL BE
SLOW...AND THE OFFICIAL FORECAST THUS CALLS FOR A SLOW
WEST-NORTHWESTWARD DRIFT ALONG THE LINES OF THAT OF THE PREVIOUS
FORECAST.  GIVEN THAT THE 120 HR TRACK GUIDANCE POSITIONS RANGE
BETWEEN 124W AND 141W...THIS IS A LOW CONFIDENCE FORECAST.

GIVEN THE CURRENT INCREASE IN ORGANIZATION...THE INTENSITY FORECAST
WILL CHANGE TO INCLUDE SOME MODEST STRENGTHENING DURING THE NEXT 24
HR.  BEYOND THAT TIME...IF THE STORM FOLLOWS THE FORECAST TRACK IT
WILL BE NEAR OR OVER 26C SEA SURFACE TEMPERATURES IN 48-72 HR AND
OVER 25C BY 120 HR.  THIS SHOULD RESULT IN SOME GRADUAL WEAKENING. 
THE INTENSITY FORECAST IS IN GENERAL AGREEMENT WITH SHIPS AND THE
GFDL.
 
FORECASTER BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      14/1500Z 16.9N 130.1W    45 KT
 12HR VT     15/0000Z 17.0N 130.6W    50 KT
 24HR VT     15/1200Z 17.2N 131.3W    50 KT
 36HR VT     16/0000Z 17.4N 131.8W    45 KT
 48HR VT     16/1200Z 17.6N 132.1W    45 KT
 72HR VT     17/1200Z 18.0N 132.5W    45 KT
 96HR VT     18/1200Z 18.5N 133.0W    40 KT
120HR VT     19/1200Z 18.5N 133.5W    35 KT
 
 
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