Tropical Storm ISIS
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TTAA00 KNHC DDHHMM
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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