775 
 WTPZ42 KNHC 131433
 TCDEP2
 TROPICAL STORM ISIS DISCUSSION NUMBER  22
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
 8 AM PDT MON SEP 13 2004
  
 ENHANCED INFRARED ANIMATION DEPICTS THAT THE LOW-LEVEL CIRCULATION
 CENTER REMAINS DISPLACED ABOUT 30 NM TO THE NORTHEAST OF WEAKENING
 DEEP CONVECTION. LAST NIGHT'S QUIKSCAT AMBIGUITY ANALYSIS SUPPORTS
 A POSITION SLIGHTLY FARTHER SOUTH THAN PREVIOUSLY THOUGHT. UW-CIMSS
 ANALYSES INDICATES THAT 10 TO 20 KT OF EASTERLY SHEAR PERSISTS OVER
 ISIS. CURRENT SATELLITE INTENSITY ESTIMATES REMAIN AT 45 KT...
 ALTHOUGH DATA-T NUMBERS HAVE DECREASED TO 2.0 AND 2.5...30 AND 35
 KT RESPECTIVELY. THE QUIKSCAT PASS ALSO REVEALED NUMEROUS 40 AND 45
 KT FLAGGED BUT POSSIBLY VALID WIND VECTORS OVER THE SOUTHWEST
 QUADRANT. WE WILL WAIT FOR VISIBLE IMAGERY AND THIS AFTERNOON'S
 QUIKSCAT PASS BEFORE DECREASING THE INTENSITY. THE FORECAST
 INTENSITY FOLLOWS CLOSER TO THE THE GFDL THAN THE SHIPS. AS
 MENTIONED IN EARLIER DISCUSSIONS...SHIPS HAS INDICATED CONSIDERABLY
 UNREALISTICALLY LOW SHEAR VALUES OVER THE PAST FEW DAYS.
 
 INITIAL MOTION IS WESTWARD OR 270/9 KT.  GLOBAL MODELS AND THE GFDL
 DEPICT A RIDGE TO THE NORTHWEST OF ISIS GRADUALLY WEAKENING AND
 RETROGRADING WEST AFTER THE 48 HOUR PERIOD.  AFTERWARD...GUIDANCE
 SUGGESTS ISIS SHOULD SLOW AND DRIFT OR STAIR-STEP WITHIN A
 DEVELOPING WEAKNESS EXPECTED TO EXTEND SOUTHWEST FROM SOUTHERN
 CALIFORNIA/BAJA. MODELS ARE ALSO SHOWING A PERIPHERAL RIDGE
 BUILDING SLIGHTLY BETWEEN ISIS AND JAVIER...WHICH WOULD ALSO
 SUPPORT A SLIGHT DRIFT NORTH LATE IN THE PERIOD. THE OFFICIAL
 FORECAST IS SIMILAR TO THE PREVIOUS AND AGREES WITH THE CONU
 CONSENSUS. 
  
 FORECASTER ROBERTS/FRANKLIN
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      13/1500Z 17.3N 127.3W    45 KT
  12HR VT     14/0000Z 17.3N 128.5W    45 KT
  24HR VT     14/1200Z 17.3N 129.8W    50 KT
  36HR VT     15/0000Z 17.3N 130.8W    50 KT
  48HR VT     15/1200Z 17.4N 131.2W    50 KT
  72HR VT     16/1200Z 17.5N 131.5W    50 KT
  96HR VT     17/1200Z 17.5N 132.0W    50 KT
 120HR VT     18/1200Z 18.0N 132.5W    50 KT
  
  
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