Hurricane ISIS

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TROPICAL STORM ISIS DISCUSSION NUMBER  33
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2 AM PDT THU SEP 16 2004
 
THE INTENSITY ESTIMATE OF ISIS REMAINS AT 55 KTS BASED ON UW-CIMSS
AND CSU-CIRA AMSU ALGORITHMS WHICH YIELD A CONSISTENT MINIMUM
PRESSURE ESTIMATE OF 992 MB AND AN INTENSITY OF 55 KTS. THE CURRENT
INTENSITY ESTIMATES FROM TAFB...SAB..AND AFWA YIELD A SOMEWHAT
LOWER INTENSITY OF 45 KTS...HOWEVER THE OFFICIAL INTENSITY IS HELD
AT 55 KTS BASED ON THE CONSISTENT RESULTS FROM THE OBJECTIVE
ANALYSES.

THE INITIAL MOTION IS STILL DIFFICULT TO DISCERN...BUT IT APPEARS
STATIONARY. ISIS REMAINS EMBEDDED IN WEAK STEERING CURRENTS AND IS
EXPECTED TO CONTINUE DRIFTING WESTWARD OVER THE NEXT FIVE DAYS. THE
MODEL GUIDANCE FOR THIS ADVISORY CALLS FOR A SLOW WESTWARD TO
WEST-SOUTHWESTWARD DRIFT...THEREFORE THE OFFICIAL FORECAST TRACK
FOLLOWS THIS SCENARIO.

SINCE ISIS HAS MOVED GENERALLY NORTHWARD...IT HAS TRACKED OVER
SLIGHTLY COOLER SSTS OF 25 DEGREES CELSIUS AND THIS HAS LIKELY KEPT
CONVECTION TO A MINIMUM. HOWEVER...THE PROJECTED WEST AND SOUTHWEST
TRACK OF ISIS MAY ALLOW FOR SOME REDEVELOPMENT AS IT CROSSES BACK
INTO A BIT WARMER SST REGIME...BUT AT THIS TIME THE OFFICIAL
INTENSITY FORECAST WILL ASSUME A GRADUAL WEAKENING TREND UNTIL THAT
SCENARIO UNFOLDS.
 
FORECASTER SISKO/JARVINEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      16/0900Z 18.7N 132.3W    55 KT
 12HR VT     16/1800Z 18.7N 132.8W    50 KT
 24HR VT     17/0600Z 18.7N 133.3W    45 KT
 36HR VT     17/1800Z 18.6N 133.8W    40 KT
 48HR VT     18/0600Z 18.4N 134.2W    35 KT
 72HR VT     19/0600Z 18.3N 134.7W    30 KT
 96HR VT     20/0600Z 18.2N 135.1W    30 KT...DISSIPATING
120HR VT     21/0600Z 18.1N 135.5W    30 KT...DISSIPATING
 
 
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