Tropical Storm ISIS
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TROPICAL STORM ISIS DISCUSSION NUMBER 17
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2 AM PDT SUN SEP 12 2004
ENHANCED INFRARED IMAGERY INDICATE PERSISTANT DEEP CONVECTION IN THE
SOUTHERN SEMI-CIRCLE OF THE SYSTEM...AS WELL AS A SMALL AREA TO THE
NORTHEAST OF THE CENTER. ALSO...WATER VAPOR IMAGERY SUGGESTS THAT
THE SHEAR IS SLOWLY DECREASING OVER THE SYSTEM. THE SYSTEM IS
BECOMING BETTER ORGANIZED AND THIS IS REFLECTED IN THE T3.0
CLASSIFICATIONS FROM TAFB AND SAB. THE INITIAL INTENSITY IS NOW SET
AT 45 KTS. THE SHIPS GUIDANCE NOW SHOWS A GRADUAL INTENSIFICATION
TO 65 KT IN 60 TO 72 HOURS. THE OFFICIAL INTENSITY FORECAST FOLLOWS
THE SHIPS GUIDANCE BUT ONLY TO 60 KTS.
ISIS IS MOVING ON THE SOUTH SIDE OF OF A WELL POSITIONED RIDGE TO
THE NORTH. THE INITIAL MOTION IS WESTWARD OR 270/10. ISIS HAS BEEN
RUNNING DUE WEST ALONG 17.4 NORTH FOR THE PAST 24 HOURS AND MOVING
ONE WHOLE DEGREE OF LONGITUDE EVERY 6 HOURS. THE DYNAMICAL TRACK
GUIDANCE REMAINS CLUSTERED ON THIS CONTINUED WESTWARD TRACK THROUGH
THE PERIOD WITH A DECREASE IN FORWARD SPEED IN THE LATER FORECAST
PERIODS. THE CURRENT OFFICIAL TRACK FORECAST IS BASICALLY AN
UPDATE OF THE PREVIOUS ONE.
FORECASTER JARVINEN
FORECAST POSITIONS AND MAX WINDS
INITIAL 12/0900Z 17.4N 123.5W 45 KT
12HR VT 12/1800Z 17.4N 125.0W 50 KT
24HR VT 13/0600Z 17.4N 127.0W 55 KT
36HR VT 13/1800Z 17.4N 128.5W 60 KT
48HR VT 14/0600Z 17.4N 129.8W 60 KT
72HR VT 15/0600Z 17.4N 132.0W 60 KT
96HR VT 16/0600Z 17.4N 133.4W 60 KT
120HR VT 17/0600Z 17.4N 134.8W 60 KT
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