049 
 WTNT43 KNHC 181435
 TCDAT3
 HURRICANE HELENE DISCUSSION NUMBER  25
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082006
 1100 AM EDT MON SEP 18 2006
  
 HELENE AND GORDON WERE BASICALLY AT THE SAME LONGITUDE THIS MORNING
 AND THERE WAS A WEAKENING ON THE RIDGE NORTH OF HELENE. THIS
 RESULTED IN HELENE MOVING IN A NORTH-NORTHWESTWARD TRACK FOR THE
 PAST SEVERAL HOURS.  HOWEVER...IT APPEARS THAT THE HURRICANE IS
 READY TO BEGIN THE WESTWARD TURN ANTICIPATED BY THE GLOBAL MODELS.
 IN FACT...HELENE HAS ALREADY TURNED A LITTLE BIT AND IS NOW MOVING
 TOWARD THE NORTHWEST OR 310 DEGREES AT 8 KNOTS. THE TROUGH
 CURRENTLY LOCATED OVER THE WESTERN ATLANTIC IS FORECAST TO WEAKEN
 WHILE A RIDGE TO THE NORTH OF HELENE IS EXPECTED TO AMPLIFY. THIS
 PATTERN WOULD TEMPORARILY STEER HELENE ON A WESTWARD TRACK FOR A
 COUPLE OF DAYS.  THEREAFTER...GLOBAL MODELS SHOW ANOTHER LARGE
 TROUGH APPROACHING THE EASTERN UNITED STATES. THIS TROUGH WILL
 FORCE HELENE SLOWLY NORTHWARD. ALTHOUGH...THE CONFIDENCE IS QUITE
 HIGH THAT HELENE WILL EVENTUALLY TURN NORTHWARD...IT IS VERY
 DIFFICULT TO FORECAST THE LONGITUDE THIS WILL OCCUR. THERE ARE SOME
 INDICATIONS FROM THE LAST RUN OF THE GLOBAL MODELS THAT BY DAYS 4
 AND 5...THE STEERING CURRENTS WILL WEAKEN AND HELENE WILL BE MOVING
 VERY SLOWLY.        
 
 THERE HAS NO SIGNIFICANT CHANGE IN THE CLOUD PATTERN...JUST A SMALL
 INCREASE IN THE DVORAK T-NUMBERS. THEREFORE...THE INTENSITY HAS
 BEEN ADJUSTED UPWARD TO 110 KNOTS.  A NOAA P3 PLANE AND NOAA G4
 JET...CURRENTLY ON A RESEARCH MISSION IN THE AREA WILL BE PROVIDING
 VALUABLE DATA THIS AFTERNOON AND WE COULD HAVE A BETTER ESTIMATE OF
 THE STRUCTURE OF THE HURRICANE AND THE STEERING.  HELENE COULD
 STRENGTHEN JUST LITTLE BIT MORE SINCE THE SHEAR IS LOW AND THE
 OCEAN IS WARM.  HOWEVER...MOST OF THE INTENSITY GUIDANCE FORECAST
 LITTLE CHANGE OR GRADUAL WEAKENING.
 
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      18/1500Z 23.2N  50.2W   110 KT
  12HR VT     19/0000Z 23.9N  51.0W   110 KT
  24HR VT     19/1200Z 24.3N  52.8W   115 KT
  36HR VT     20/0000Z 24.3N  54.5W   115 KT
  48HR VT     20/1200Z 24.5N  56.0W   110 KT
  72HR VT     21/1200Z 27.0N  58.0W   105 KT
  96HR VT     22/1200Z 29.5N  59.5W   100 KT
 120HR VT     23/1200Z 31.5N  60.5W    95 KT
  
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