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Tropical Storm ISIS


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TROPICAL DEPRESSION ISIS DISCUSSION NUMBER  11
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2 PM PDT FRI SEP 10 2004
 
ISIS HAS REMAINED CONVENTION FREE FOR MOST OF THE DAY...DESPITE AN
APPARENTLY FAVORABLE ATMOSPHERE AND WARM OCEAN.  ALL THAT REMAINS
IS A LOW LEVEL WELL-DEFINED CIRCULATION.  THE SYSTEM WAS
UNCLASSIFIABLE BY THE SUBJECTIVE DVORAK TECHNIQUE BUT MAINTAINED A
1.5 FT/2.0 CI FROM ALL AGENCIES BASED ON THE MODEL EXPECTED
T-NUMBER.  A 13Z QUIKSCAT PASS INDICATED WINDS HAVE FALLEN BELOW
TROPICAL STORM STRENGTH.  BASED ON THE ABOVE INFORMATION...ISIS HAS
BEEN DOWNGRADED TO A TROPICAL DEPRESSION.  EVEN THOUGH THE SHIPS
AND GFDL MODELS TRY TO RE-INTENSIFY ISIS AFTER 36-48 HOURS...IT
WILL BE DIFFICULT FOR ISIS TO RECOVER AND THE INTENSITY FORECAST
KEEPS ISIS AS A DEPRESSION UNTIL DISSIPATION OCCURS IN 96
HOURS...IF NOT SOONER.
 
THE INITIAL MOTION IS 280/9.  ISIS CONTINUES TO MOVE SOUTH OF A
DEEP-LAYER RIDGE WHICH IS ANTICIPATED TO PERSIST THROUGH THE
FORECAST PERIOD.  MODEL GUIDANCE IS TIGHTLY CLUSTERED ON A WESTERLY
TRACK BUT IS A BIT SLOWER THAN THE PREVIOUS FORECAST DUE TO THE
WEAKENED STRENGTH OF THE CYCLONE AND SUBSEQUENT DECOUPLING FROM THE
STRONG UPPER-LEVEL EASTERLIES.  THE OFFICIAL FORECAST FOLLOWS THE
PREVIOUS TRACK BUT MAINTAINS THE CYCLONE WITH THE CURRENT INITIAL
MOTION.
 
FORECASTER MAINELLI/FRANKLIN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      10/2100Z 17.5N 117.1W    30 KT
 12HR VT     11/0600Z 17.9N 118.5W    30 KT
 24HR VT     11/1800Z 18.5N 120.9W    30 KT
 36HR VT     12/0600Z 18.7N 123.4W    30 KT
 48HR VT     12/1800Z 18.8N 126.0W    30 KT...DISSIPATING
 72HR VT     13/1800Z 19.0N 131.0W    30 KT...REMNANT LOW
 96HR VT     14/1800Z 19.0N 136.0W    25 KT...REMNANT LOW
120HR VT     15/1800Z...DISSIPATED
 
 
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