Tropical Storm ISIS

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TROPICAL STORM ISIS DISCUSSION NUMBER   8
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
8 PM PDT THU SEP 09 2004
 
ISIS IS STILL FEELING THE EFFECTS OF SIGNIFICANT EASTERLY SHEAR. 
OVERALL THE CONVECTIVE STRUCTURE HAS NOT CHANGED MUCH THIS EVENING. 
CLOUD TOPS REMAIN COLD AND ARE SOMEWHAT CLOSER TO THE LOW LEVEL
CIRCULATION CENTER THAN YESTERDAY.  SATELLITE CLASSIFICATION
INTENSITY ESTIMATES ARE 35/45/45 KT FROM SAB/TAFB/KGWC.  BECAUSE OF
A LACK OF ADDITIONAL OBSERVATIONAL EVIDENCE AND THE STEADY STATE OF
THE SATELLITE PRESENTATION...THE INITIAL INTENSITY REMAINS AT 40
KT.

THE INITIAL MOTION IS STILL WEST-NORTHWESTWARD AT ABOUT 8 KT.  THE
FORECAST TRACK IS VERY SIMILAR TO THE PREVIOUS FORECAST.  THE MODEL
GUIDANCE HAS BEEN TRENDING TOWARD A SLOWER MOTION LATER IN THE
FORECAST PERIOD AND THIS FORECAST REFLECTS THAT.  ISIS WILL
GRADUALLY TURN TOWARD A MORE WESTERLY TRACK AS IT ENCOUNTERS
INCREASING INFLUENCE BY A BUILDING SUBTROPICAL RIDGE TO ITS NORTH.  

THE INTENSITY FORECAST REASONING HAS NOT CHANGED.  VERTICAL WIND
SHEAR IS FORECAST TO RELAX OVER THE NEXT DAY OR TWO WITH ISIS STILL
LOCATED OVER WARM SEA SURFACE TEMPERATURES.  MODEST STRENGTHENING
IS FORECAST UNTIL ISIS MOVES OVER A COLDER SEA SURFACE AROUND THE 3
DAY TIME FRAME.  AFTER THAT TIME...ISIS WILL GRADUALLY WEAKEN AS IT
CONTINUES TO MOVE IN A WESTERLY FASHION OVER INCREASINGLY
UNFAVORABLE SEA SURFACE TEMPERATURES.

FORECASTER BEVEN/HENNON

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      10/0300Z 17.4N 114.6W    40 KT
 12HR VT     10/1200Z 17.8N 116.0W    45 KT
 24HR VT     11/0000Z 18.4N 118.2W    45 KT
 36HR VT     11/1200Z 18.9N 120.7W    50 KT
 48HR VT     12/0000Z 19.4N 123.0W    50 KT
 72HR VT     13/0000Z 19.5N 128.1W    45 KT
 96HR VT     14/0000Z 19.5N 133.2W    40 KT
120HR VT     15/0000Z 19.5N 138.8W    40 KT
 
 
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