943 
 WTNT44 KNHC 081448
 TCDAT4
 HURRICANE IVAN DISCUSSION NUMBER  25
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
 11 AM EDT WED SEP 08 2004
 
 LAST FIX FROM A RECONNAISSANCE PLANE EARLIER THIS MORNING INDICATED
 THAT THE PRESSURE INCREASED TO 955 MB BUT FLIGHT-LEVEL WINDS WERE
 STILL 133 KNOTS IN THE NORTHERN EYEWALL. SINCE THEN...HIGH
 RESOLUTION VISIBLE SATELLITE IMAGES REVEAL THAT THE EYE IS NOT AS
 DISTINCT AS EARLIER BUT STILL VISIBLE. INITIAL INTENSITY REMAINS AT
 120 KNOTS. BECAUSE THE HURRICANE WILL HAVE TO FIGHT SOME SHEAR AND
 WILL BE MOVING JUST NORTH OF THE SOUTH AMERICAN COAST...THERE MAY
 BE SOME WEAKENING DURING THE NEXT 12 TO 24 HOURS. THEREAFTER...THE
 HURRICANE WILL BE OVER THE NORTHWESTERN CARIBBEAN SEA WHERE THERE
 IS HIGH OCEANIC HEAT CONTENT AND LOWER SHEAR. SO...IVAN IS EXPECTED
 TO INTENSIFY BEFORE REACHING CUBA. NEVERTHERELESS...THESE ARE
 BASICALLY FLUCTUATIONS IN INTENSITY AND THE BOTTOM LINE IS THAT
 IVAN IS EXPECTED TO REMAIN A VERY DANGEROUS HURRICANE.    
 
 SATELLITE AND EARLIER RECONNAISSANCE FIXES INDICATE THAT IVAN IS
 MOVING TOWARD THE WEST-NORTHWEST OR 285 DEGREES AT 14 KNOTS. DURING
 THE NEXT 24 TO 48 HOURS...THE SUBTROPICAL RIDGE TO THE NORTH OF
 IVAN IS EXPECTED TO CHANGE LITTLE...FORCING IVAN TO MOVE TOWARD THE
 WEST-NORTHWEST. THEREAFTER...THE RIDGE IS FORECAST TO WEAKEN AND A
 BROAD MID-LEVEL TROUGH WILL LIKELY BECOME ESTABLISHED OVER THE GULF
 OF MEXICO. THIS PATTERN SHOULD MOVE THE HURRICANE ON A NORTHWEST
 AND NORTH-NORTHWEST TRACK WITH A DECREASE IN FORWARD SPEED. IT MUST
 BE EMPHASIZED THAT THE FORECAST TRACK BEYOND 72 HOURS IS HIGHLY
 UNCERTAIN SINCE STEERING CURRENTS WILL BE WEAK AND ARE CURRENTLY
 NOT WELL-DEFINED IN THE FORECAST MODELS. IN FACT...SOME RELIABLE
 MODELS BRING IVAN OVER FLORIDA AND ANOTHER RELIABLE GROUP MOVE THE
 HURRICANE TOWARD THE GULF OF MEXICO. THERE IS NO APPARENT REASON TO
 FAVOR ONE SCENARIO OVER THE OTHER AT THIS TIME. THEREFORE...THE
 OFFICIAL FORECAST REMAINS NEAR THE GLOBAL MODEL CONSENSUS AND
 PRESUMES THAT THERE WILL BE ENOUGH RIDGING TO KEEP THE HURRICANE ON
 A NORTHWEST TO NORTH-NORTHWEST TRACK... BRINGING DANGEROUS IVAN
 OVER WESTERN CUBA IN 4 DAYS AND INTO THE EASTERN GULF OF MEXICO BY
 DAY FIVE.   
  
 FORECASTER AVILA
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      08/1500Z 12.7N  66.2W   120 KT
  12HR VT     09/0000Z 13.3N  68.3W   115 KT
  24HR VT     09/1200Z 14.5N  71.0W   120 KT
  36HR VT     10/0000Z 16.0N  73.5W   125 KT
  48HR VT     10/1200Z 17.5N  76.0W   125 KT NEAR JAMAICA
  72HR VT     11/1200Z 19.5N  79.0W   125 KT
  96HR VT     12/1200Z 22.5N  82.0W   125 KT  OVER WESTERN CUBA 
 120HR VT     13/1200Z 26.0N  84.0W   115 KT
  
  
 $$