Hurricane IKE
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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
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FORECASTER PASCH/BROWN
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