Official Discussion issued by the National Hurricane Center
IKE (AL092008) DATA RELEASED: 9/11/2008 9:00:00 AM UTC
Copy of official data HURRICANE IKE DISCUSSION NUMBER 41 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092008 500 AM EDT THU SEP 11 2008 IKE CONTINUES TO EXHIBIT SOME UNUSUAL STRUCTURAL CHARACTERISTICS. DROPSONDE AND FLIGHT-LEVEL WIND DATA INDICATE THAT THE INTENSITY IS STILL NEAR 85 KT...WHICH IS ANOMALOUSLY LOW FOR THE REPORTED CENTRAL PRESSURE. THE LATTER VALUE...946 MB...WOULD NORMALLY CORRESPOND TO A BORDERLINE CATEGORY 3/4 HURRICANE. THE TROPICAL CYCLONE HAS A VERY LARGE WIND FIELD...PARTICULARLY OVER THE NORTHERN SEMICIRCLE AS OBSERVED BY BUOYS AND SHIPS OVER THE NORTHERN GULF. HOWEVER IT CONTINUES TO HAVE A SMALL INNER CORE WITH AN EYE JUST UNDER 10 N MI IN DIAMETER. THERE HAS BEEN A DOUBLE WIND MAXIMUM...ALTHOUGH HURRICANE HUNTER OBSERVATIONS SUGGEST THAT THE OUTER WIND BAND IS BEGINNING TO CONTRACT. OCEANIC CONDITIONS APPEAR NEUTRAL ALONG THE PATH OF IKE AS IT WILL LIKELY TRAVERSE JUST TO THE NORTH OF A COUPLE OF WARM EDDIES OVER THE WESTERN GULF. GLOBAL MODELS CONTINUE TO INDICATE A FAVORABLE UPPER-LEVEL ENVIRONMENT OVER THE NEXT DAY OR TWO WITH MODEST VERTICAL SHEAR AND ANTICYCLONIC FLOW. IKE IS FORECAST TO STRENGTHEN TO MAJOR HURRICANE STATUS PRIOR TO LANDFALL...WHICH IS SIMILAR TO WHAT WAS INDICATED IN THE PREVIOUS OFFICIAL INTENSITY FORECAST. FIXES FROM THE CURRENT AIR FORCE HURRICANE HUNTER MISSION INDICATE THAT THE MOTION HAS TURNED BACK TO THE WEST-NORTHWEST...I.E. 295/8. THE TRACK MODELS REMAIN IN GOOD AGREEMENT ON A CONTINUED WEST- NORTHWESTWARD MOTION FOR THE NEXT 36-48 HOURS...TO THE SOUTH OF A STRONG MID-TROPOSPHERIC RIDGE THAT EXTENDS FROM THE SOUTHEASTERN UNITED STATES TO TEXAS. DYNAMICAL MODELS PREDICT THAT THE PORTION OF THE RIDGE OVER TEXAS WILL WEAKEN IN ABOUT 48 HOURS AND THIS WOULD CAUSE IKE TO TURN TO THE NORTHWEST AND NORTH. THERE CONTINUES TO BE SOME DISAGREEMENT AMONG THE MODELS AS TO HOW SOON AND HOW SHARP OF A TURN WILL OCCUR. HOWEVER...THE CONSENSUS OF OUR MOST RELIABLE TRACK FORECAST MODELS IS UNCHANGED FROM THE PREVIOUS ADVISORY. THEREFORE I HAVE MADE ESSENTIALLY NO CHANGES TO THE OFFICIAL TRACK FORECAST. THIS IS BETWEEN THE LATEST HWRF RUN...WHICH IS TO THE LEFT OF THE OFFICIAL FORECAST...AND THE LATEST GFDL RUN....WHICH IS TO THE RIGHT. IN THIS CASE IT IS PARTICULARLY IMPORTANT NOT TO FOCUS ON THE EXACT FORECAST TRACK SINCE DAMAGING WINDS EXTEND SO FAR FROM THE CENTER. THE EXPANSION OF THE 34-KT WIND FIELD OVER THE NORTHEAST QUADRANT NECESSITATES AN EXTENSION OF THE TROPICAL STORM WARNING A LITTLE FATHER NORTHWARD AND EASTWARD ALONG THE NORTHERN GULF COAST. FORECAST POSITIONS AND MAX WINDS INITIAL 11/0900Z 25.2N 87.6W 85 KT 12HR VT 11/1800Z 25.7N 89.0W 90 KT 24HR VT 12/0600Z 26.3N 91.0W 95 KT 36HR VT 12/1800Z 27.1N 93.2W 105 KT 48HR VT 13/0600Z 28.4N 95.2W 110 KT 72HR VT 14/0600Z 32.5N 96.0W 40 KT...INLAND 96HR VT 15/0600Z 37.0N 90.5W 25 KT...INLAND 120HR VT 16/0600Z...ABSORBED INTO FRONTAL ZONE $$ FORECASTER PASCH/BROWN |