241 
 WTNT43 KNHC 190228
 TCDAT3
 HURRICANE HELENE DISCUSSION NUMBER  27
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082006
 1100 PM EDT MON SEP 18 2006
 
 ALTHOUGH THE CLOUD PATTERN OF HELENE IS SLIGHTLY ELONGATED TO THE
 NORTH...THE SATELLITE PRESENTATION OF THE CORE OF THE HURRICANE HAS
 BECOME MORE IMPRESSIVE OVER THE PAST FEW HOURS.  CENTRAL CONVECTION
 IS COOLING AND THE EYE IS BECOMING BETTER DEFINED. CIRRUS OUTFLOW
 IS RATHER SYMMETRICAL AND EXPANDING.  DVORAK T-NUMBERS OF 5.5 FROM
 ALL AGENCIES SUPPORT KEEPING THE INTENSITY AT 100 KT AT THIS TIME. 
 THE HURRICANE WILL CONTINUE TO MOVE OVER WARM OCEAN WATERS AND THE
 VERTICAL SHEAR IS EXPECTED TO REMAIN WEAK OVER THE NEXT COUPLE OF
 DAYS.  STRENGTHENING IS LIKELY AND THE OFFICIAL WIND SPEED FORECAST
 IS SLIGHTLY HIGHER THAN THE SHIPS...GFDL...AND FSU SUPERENSEMBLE
 INTENSITY GUIDANCE.  INDEED...GIVEN THE INCREASING ORGANIZATION OF
 THE INNER CORE...THIS INTENSITY FORECAST COULD BE CONSERVATIVE...
 AND HELENE CERTAINLY HAS THE POTENTIAL TO BECOME A CATEGORY 4
 HURRICANE.
 
 HELENE IS MOVING SLOWLY WEST-NORTHWESTWARD...300/7.  A MORE WESTWARD
 COMPONENT OF MOTION IS EXPECTED DURING THE NEXT DAY OR SO AS A
 MID-TROPOSPHERIC RIDGE TEMPORARILY BUILDS TO THE NORTH OF THE
 TROPICAL CYCLONE.  THE GFDL MODEL EVEN DEPICTS A TURN TOWARD THE
 WEST-SOUTHWEST IN 12 HOURS OR SO.  BY 48 HOURS...HOWEVER...A VERY
 LARGE 500 MB TROUGH MOVING EASTWARD NEAR THE U.S. EAST COAST SHOULD
 INDUCE A TURN TOWARD THE NORTHWEST AND NORTH-NORTHWEST.  IN 3 TO 5
 DAYS HELENE SHOULD BEGIN TO BE STEERED BY THE FLOW ON THE SOUTHERN
 PART OF THE TROUGH AND TURN TOWARD THE NORTH AND NORTHEAST.  THE
 OFFICIAL FORECAST FOR THIS ADVISORY PACKAGE IS IN REASONABLE
 AGREEMENT WITH THE DYNAMICAL MODEL CONSENSUS AS WELL AS THE
 GFDL...AND ALSO SIMILAR TO THE PREVIOUS NHC TRACK.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      19/0300Z 24.2N  51.4W   100 KT
  12HR VT     19/1200Z 24.6N  52.7W   105 KT
  24HR VT     20/0000Z 25.0N  54.4W   110 KT
  36HR VT     20/1200Z 25.4N  55.9W   110 KT
  48HR VT     21/0000Z 26.7N  57.1W   110 KT
  72HR VT     22/0000Z 31.0N  58.0W   100 KT
  96HR VT     23/0000Z 35.5N  56.0W    90 KT
 120HR VT     24/0000Z 39.0N  51.0W    80 KT
  
 $$