000 WTNT44 KNHC 082036 TCDAT4 HURRICANE IVAN DISCUSSION NUMBER 26 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 PM EDT WED SEP 08 2004 TODAY HAS BEEN A HISTORIC DAY FOR THE DEPARTMENT OF COMMERCE/ NATIONAL OCEANIC ATMOPHERIC ADMINISTRATION/NATIONAL WEATHER SERVICE/NATIONAL HURRICANE CENTER. THE PRESIDENT OF THE UNITED STATES VISITED THE FACILITIES AT MIAMI FLORIDA. A RECONNAISSANCE PLANE JUST PENETRATED THE EYE OF THE HURRICANE AND REPORTED A MINIMUM PRESSURE OF 947 MB. SATELLITE IMAGES INDICATE THAT THE HURRICANE CONTINUES TO BE WELL-ORGANIZED WITH A DISTINCT EYE...SURROUNDED COMPLETELY BY VERY DEEP CONVECTION. THE OUTFLOW IS EXCELLENT OUTFLOW. INITIAL INTENSITY REMAINS AT 120 KNOTS. IT APPEARS THAT IVAN IS OVERCOMING THE SHEAR AND HEADING TOWARD A MORE FAVORABLE ATMOSPHERIC AND OCEANIC ENVIRONMENT FOR STRENGTHENING. AFTER CROSSING CUBA...THE SHEAR IS FORECAST TO INCREASE AND THE OCEAN IS NOT AS WARM. THEREFORE SOME WEAKENING IS POSSIBLE. HOWEVER...IVAN IS EXPECTED TO REMAIN A VERY DANGEROUS HURRICANE. IVAN HAS BEEN MOVING TOWARD THE WEST-NORTHWEST AND IS NOW MOVING 295 DEGREES AT 15 KNOTS. AS INDICATED IN THE PREVIOUS FORECAST... DURING THE NEXT 24 TO 48 HOURS...THE SUBTROPICAL RIDGE TO THE NORTH OF IVAN IS EXPECTED TO CHANGE LITTLE...KEEPING IVAN ON A WEST-NORTHWEST TRACK. 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 STEER THE HURRICANE ON A NORTHWEST AND NORTH-NORTHWEST TRACK WITH A DECREASE IN FORWARD SPEED. IT MUST BE RE-EMPHASIZED THAT THE FORECAST TRACK BEYOND 72 HOURS CONTINUES TO BE HIGHLY UNCERTAIN SINCE STEERING CURRENTS ARE FORECAST TO BE WEAK AND NOT WELL-DEFINED IN THE FORECAST MODELS. THE SPREAD IN THE MODELS CONTINUES IN THE LATEST 12Z RUN. SOME MODELS BRING IVAN OVER FLORIDA AND ANOTHER 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 08/2100Z 13.4N 67.7W 120 KT 12HR VT 09/0600Z 14.2N 69.8W 125 KT 24HR VT 09/1800Z 15.5N 72.5W 120 KT 36HR VT 10/0600Z 17.0N 74.7W 125 KT 48HR VT 10/1800Z 18.5N 77.0W 130 KT OVER JAMAICA 72HR VT 11/1800Z 20.5N 80.0W 130 KT 96HR VT 12/1800Z 22.5N 82.0W 120 KT OVER WESTERN CUBA 120HR VT 13/1800Z 26.0N 83.5W 115 KT $$