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| #7955 (Received by flhurricane at: 6:44 PM 11.Sep.2004) TCDAT4 HURRICANE IVAN DISCUSSION NUMBER 38 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 PM EDT SAT SEP 11 2004 THERE HAVE BEEN SOME GRADUAL CHANGES IN THE STEERING PATTERN OVER THE LAST DAY OR SO WHICH COULD RESULT IN THE HURRICANE MOVING ON A TRACK NOT AS CLOSE TO SOUTH FLORIDA. WHILE THIS MAY BE GOOD NEWS FOR SOUTH FLORIDA...IT IS NOT SO FOR OTHER REGIONS OF THE EASTERN GULF COAST. WATER VAPOR IMAGES SHOW THAT A RIDGE OF HIGH PRESSURE AT THE MID TO UPPER-LEVELS HAS DEVELOPED FROM THE GULF OF MEXICO EASTWARD ACROSS FLORIDA. IT APPEARS THAT THIS RIDGE HAS BEEN FORCING THE HURRICANE ON A MORE WESTWARD TRACK...DELAYING THE EXPECTED NORTHWEST AND NORTHWARD TURN. ALTHOUGH THE NORTHWARD TURN IS STILL FORECAST TO OCCUR AS A WEAKNESS DEVELOPS IN THE GULF OF MEXICO...IT IS NOW EXPECTED TO OCCUR OVER EXTREME WESTERN CUBA AND OVER THE OPEN WATERS OF THE GULF OF MEXICO. THIS TRACK INCREASES THE HURRICANE RISK FOR THE NORTHEASTERN GULF OF MEXICO REGION AND DECREASES IT FOR SOUTH FLORIDA. THE WESTWARD SHIFT OF THE OFFICIAL FORECAST REMAINS IN AGREEMENT WITH GUIDANCE WHICH HAS ALSO BEEN SHIFTING GRADUALLY WESTWARD. AS WAS THOUGHT POSSIBLE...IVAN HAS REGAINED CATEGORY FIVE STRENGTH. A RECONNAISSANCE PLANE JUST MEASURED 161 KNOTS AT 700 MB AND AN EXTRAPOLATED PRESSURE OF 914 MB. THE DROP MEASURED 918 MB BUT IT HAD 29 KNOTS AT THE SURFACE. INITIAL INTENSITY HAS BEEN INCREASED TO 145 KNOTS. THERE ARE NO SKILLS IN PREDICTING CHANGES IN INTENSITY WITH SUCH EXTREMELY INTENSE HURRICANES...SO IVAN IS KEPT AT 145 KNOTS UNTIL LANDFALL IN CUBA. THEREAFTER...THE SHEAR IS FORECAST TO INCREASE...SO A GRADUAL WEAKENING IS INDICATED. NEVERTHERLESS... IVAN IS EXPECTED TO REACH THE UNITES STATES AS A MAJOR HURRICANE. FORECASTER AVILA FORECAST POSITIONS AND MAX WINDS INITIAL 11/2100Z 18.2N 79.3W 145 KT 12HR VT 12/0600Z 18.7N 80.5W 145 KT 24HR VT 12/1800Z 20.0N 82.0W 145 KT 36HR VT 13/0600Z 21.5N 83.1W 145 KT...NEARING CUBA 48HR VT 13/1800Z 23.1N 84.0W 130 KT 72HR VT 14/1800Z 26.5N 85.0W 115 KT 96HR VT 15/1800Z 31.0N 85.0W 60 KT...INLAND 120HR VT 16/1800Z 36.0N 83.0W 25 KT...INLAND |
