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Tropical Storm ISIS (Text)

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TROPICAL DEPRESSION ISIS DISCUSSION NUMBER  15
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2 PM PDT SAT SEP 11 2004
 
VISIBLE AND ENHANCED INFRARED ANIMATION DEPICT THAT THE PARTIALLY
EXPOSED LOW-LEVEL CIRCULATION CENTER OF ISIS HAS TUCKED IN BENEATH
THE NORTHEASTERN EDGE OF A NEW BURST OF DEEP CONVECTION. IMAGERY
ALSO SHOWS A DEVELOPING BANDING FEATURE WRAPPING IN FROM THE WEST
QUADRANT. SATELLITE CURRENT INTENSITY ESTIMATES ARE 35 KT FROM TAFB
AND 30 KT FROM AFWA AND SAB.  WE WILL WAIT TO SEE IF THE BANDING
FEATURES BECOME BETTER DEFINED BEFORE RE-UPGRADING ISIS TO A
TROPICAL STORM. THE SHIPS AND NOW THE GFDL SHOW A GRADUAL
INTENSIFICATION TREND THROUGH 72 HOURS BEFORE LEVELING OFF.
UW-CIMSS WIND SHEAR ANALYSIS CONTINUES TO SHOW 10 TO 20 KT OF
EASTERLY SHEAR...HOWEVER...LARGE SCALE MODELS AND THE INTENSITY
GUIDANCE SUGGESTS THAT THE SHEAR WILL WEAKEN. THE FORECAST
INTENSITY IS SIMILAR TO THE PREVIOUS FORECAST AND AGREES WITH THE
SHIPS AND THE GFDL.
 
THE INITIAL MOTION IS WESTWARD OR 270/8. GLOBAL AND REGIONAL MODELS
ARE IN GOOD AGREEMENT ON THE STRENGTH AND ORIENTATION OF A
MID-UPPER RIDGE EXTENDING FROM MEXICO/BAJA THROUGH 48 HOURS.
AFTERWARDS...A DEEPENING MID-UPPER LEVEL TROUGH EXTENDING SOUTHWEST
FROM BAJA IS EXPECTED TO CAUSE A SLIGHT REDUCTION IN MOTION BEYOND
THE 72 HOUR PERIOD. THE OFFICIAL FORECAST IS SIMILAR TO THE
PREVIOUS FORECAST AND IS BASED OFF OF GUNA AND THE CONU CONSENSUS. 

FORECASTER ROBERTS/PASCH
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      11/2100Z 17.5N 120.8W    30 KT
 12HR VT     12/0600Z 17.5N 122.2W    35 KT
 24HR VT     12/1800Z 17.5N 124.2W    35 KT
 36HR VT     13/0600Z 17.5N 126.1W    40 KT
 48HR VT     13/1800Z 17.5N 127.9W    45 KT
 72HR VT     14/1800Z 17.5N 131.0W    45 KT
 96HR VT     15/1800Z 17.5N 132.5W    45 KT
120HR VT     16/1800Z 17.5N 134.5W    45 KT
 
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