605 
 WTPZ42 KNHC 130837
 TCDEP2
 TROPICAL STORM ISIS DISCUSSION NUMBER  21
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
 2 AM PDT MON SEP 13 2004
  
 A 530 UTC QUICK SCAT PASS SHOWS THAT THE LOW LEVEL CIRCULATION
 REMAINS ON THE EAST SIDE OF THE DEEP CONVECTION.  ISIS REMAINS
 SIGNIFICANTLY SHEARED BUT IS STILL A 45 KT TROPICAL STORM...AS
 CLASSIFIED BY TAFB AND SAB ESTIMATES.
 
 THE INITIAL MOTION IS 270/9. ISIS HAS BEEN MOVING DUE WESTWARD ON
 THE SOUTH SIDE OF A MID-PACIFIC RIDGE. THE RIDGE IS FORECAST TO
 INTENSIFY AND BLOCK THE MOTION OF ISIS IN ABOUT 36 TO 48 HOURS. THE
 MODEL GUIDANCE SUPPORTS THIS SCENARIO AND THE BLOCKING PATTERN IS
 REFLECTED IN THE...SQUASHED SPIDER...GUIDANCE PATTERN. ISIS SHOULD
 BECOME QUASI-STATIONARY AFTER 48 HOURS AND IF THE SHEAR IS STILL
 PRESENT AT THAT TIME THE SYSTEM MAY MEET ITS DEMISE AND BECOME A
 REMNANT LOW. ON THE OTHER HAND IF THE SHEAR IS LIGHT...ISIS MAY BE
 ABLE TO SURVIVE FOR SEVERAL MORE DAYS. I AM ASSUMING THE SHEAR WILL
 BE LIGHT AND ISIS WILL ACTUALLY REMAIN A 45 TO 50 KT STORM AS PER
 THE SHIPS GUIDANCE.  
  
 FORECASTER JARVINEN
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      13/0900Z 17.4N 126.2W    45 KT
  12HR VT     13/1800Z 17.4N 127.5W    45 KT
  24HR VT     14/0600Z 17.4N 129.3W    50 KT
  36HR VT     14/1800Z 17.5N 130.4W    50 KT
  48HR VT     15/0600Z 17.6N 131.2W    50 KT
  72HR VT     16/0600Z 17.7N 131.6W    50 KT
  96HR VT     17/0600Z 17.8N 131.9W    50 KT
 120HR VT     18/0600Z 18.0N 132.2W    50 KT
  
  
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