142 
 WTNT44 KNHC 062048
 TCDAT4
 HURRICANE IVAN DISCUSSION NUMBER  18
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
 5 PM EDT MON SEP 06 2004
  
 THE HURRICANE HUNTERS FOUND PEAK FLIGHT LEVEL...700 MB...WINDS OF 94
 KT AND 87 KT OVER THE NORTHWEST AND NORTHEAST QUADRANTS
 RESPECTIVELY. THIS SUPPORTS A CURRENT INTENSITY OF 90 KT...WHICH IS
 CONSISTENT WITH THE MINIMUM CENTRAL PRESSURE THEY MEASURED BY
 DROPSONDE...969 MB. THE CENTRAL PRESSURE ESTIMATE FOR THIS ADVISORY
 IS SLIGHTLY LOWER SINCE THE DROPSONDE SHOWED WINDS OVER 20 KT WHEN
 IT HIT THE SURFACE...SUGGESTING THAT IT WAS NOT IN THE CENTER OF
 THE EYE.  SATELLITE IMAGES DEPICT A WELL-ORGANIZED HURRICANE...AND
 THE UPPER-TROPOSPHERIC OUTFLOW REMAINS IMPRESSIVE.  WE SEE NO
 REASON WHY IVAN COULD NOT RESTRENGTHEN VERY SOON...AND THIS IS
 REFLECTED IN THE OFFICIAL FORECAST.
 
 INITIAL MOTION...285/19...IS NOT MUCH DIFFERENT FROM WHAT IT WAS
 EARLIER TODAY.  THE HURRICANE SHOULD CONTINUE TO BE STEERED
 WEST-NORTHWESTWARD BY A STRONG EASTERLY TO EAST-SOUTHEASTERLY 
 CURRENT FOR THE NEXT FEW DAYS.  THE DYNAMICAL TRACK MODEL
 CONSENSUS...CONU...HAS BEEN SHIFTING A LITTLE TO THE WEST
 TODAY...SO THE OFFICIAL FORECAST IS ALSO SHIFTED A LITTLE TO THE
 LEFT OF THE PREVIOUS ONE.  HOWEVER...IN THE 4-5 DAY TIME
 FRAME...THERE IS A LOT OF UNCERTAINTY AS TO HOW MUCH MID-LEVEL
 RIDGING WILL DEVELOP BETWEEN FRANCES...OR ITS REMNANTS OVER THE
 EAST-CENTRAL UNITED STATES...AND IVAN.  IF A SIGNIFICANT WEAKNESS
 IS LEFT IN THE VICINITY OF FLORIDA...IVAN COULD VEER TOWARD THE
 BAHAMAS NEAR THE END OF THE FORECAST PERIOD.  IT IS SIMPLY TOO
 EARLY TO BE MORE SPECIFIC REGARDING THE POTENTIAL THREAT TO THE
 UNITED STATES COAST. 
 
 BASED ON THE AIRCRAFT DATA...THE WIND RADII HAVE BEEN ADJUSTED TO
 SHOW A MORE ASYMMETRIC CIRCULATION.
   
 FORECASTER PASCH
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      06/2100Z 11.6N  55.3W    90 KT
  12HR VT     07/0600Z 12.3N  58.1W   100 KT
  24HR VT     07/1800Z 13.2N  61.5W   105 KT
  36HR VT     08/0600Z 14.0N  64.4W   110 KT
  48HR VT     08/1800Z 15.0N  67.4W   115 KT
  72HR VT     09/1800Z 17.5N  72.5W   120 KT
  96HR VT     10/1800Z 20.0N  76.5W    80 KT...INLAND
 120HR VT     11/1800Z 23.0N  80.0W    75 KT...INLAND
  
  
 $$