ZCZC MIATCDAT3 ALL TTAA00 KNHC DDHHMM HURRICANE ISABEL DISCUSSION NUMBER 17 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT WED SEP 10 2003 SATELLITE IMAGES SHOW A DISTINCT EYE SURROUNDED BY DEEP CONVECTION. THE OUTFLOW TO THE WEST AND SOUTH IS IMPRESSIVE BUT IS SOMEWHAT LIMITED TO THE EAST. SUBJECTIVE T-NUMBERS ARE 6.0 AND 5.5 FROM TAFB AND SAB..RESPECTIVELY. THE LATEST OBJECTIVE T-NUMBERS ARE BACK UP TO 6.0 ON THE DVORAK SCALE. INITIAL INTENSITY REMAINS AT 115 KNOTS. THERE IS NO SHEAR AND THE OCEAN IS INCREASINGLY WARMER. THESE ENVIRONMENTAL CONDITIONS SHOULD ALLOW SOME ADDITIONAL STRENGTHENING. BUT...IN MAJOR HURRICANES...CHANGES IN INTENSITY ARE CONTROLLED IN GENERAL BY EYEWALL THERMODYNAMICS. THEREFORE...SOME FLUCTUATIONS IN INTENSITY ARE INDICATED TO REFLECT UNCERTAINTIES. THE FORECAST TRACK IS BECOMING RATHER INTERESTING. LAST FEW SATELLITE IMAGES SUGGEST THAT ISABEL HAS BEGUN TO TURN TOWARD THE WEST. THE INITIAL MOTION IS NOW ESTIMATED AT 275 DEGREES AT 12 KNOTS. HOWEVER...A LONGER TERM AVERAGE IS STILL TOWARD THE WEST-NORTHWEST. GLOBAL MODELS CONTINUE TO SHOW THE DEVELOPMENT OF A STRONG SUBTROPICAL RIDGE NORTH OF ISABEL. DEPENDING UPON THE FORECAST STRENGTH OF THE RIDGE...EACH MODEL MOVES ISABEL EITHER WEST OR WEST-NORTHWEST. THE GFS HAS THE STRONGEST RIDGE AND IS PRODUCING THE SOUTHERMOST AND DANGEROUS TRACK. THE UK HAS A WEAKER RIDGE WITH THE NORTHERMOST TRACK BUT STILL INDICATING A WEST-NORTHWEST TO WEST MOTION. THE OFFICIAL FORECAST IS IN BETWEEN THESE TWO SOLUTIONS. THE NOGAPS APPEARS TO BE VERY SLOW BUT IT IS SHOWING THE SAME WEST TO WEST-NORTHWEST TREND. THE BOTTOM LINE IS THAT A RIDGE IS FORECAST TO DEVELOP BETWEEN THE U.S. EAST COAST AND BERMUDA. THIS PATTERN WOULD MAINTAIN ISABEL ON A GENERAL WEST TO WEST-NORTHWEST TRACK FOR THE NEXT SEVERAL DAYS...KEEPING THE CORE OF THE HURRICANE AWAY FROM THE NORTHERN LEEWARD ISLANDS. IF THE CURRENT WESTWARD TREND CONTINUES...THE OFFICIAL FORECAST WILL HAVE TO BE ADJUSTED SLIGHTLY SOUTHWARD IN THE NEXT TERM. FORECASTER AVILA FORECAST POSITIONS AND MAX WINDS INITIAL 10/0900Z 20.9N 50.2W 115 KT 12HR VT 10/1800Z 21.5N 52.1W 115 KT 24HR VT 11/0600Z 21.5N 54.2W 115 KT 36HR VT 11/1800Z 21.5N 56.0W 115 KT 48HR VT 12/0600Z 21.5N 58.0W 115 KT 72HR VT 13/0600Z 21.5N 60.5W 115 KT 96HR VT 14/0600Z 22.0N 63.5W 110 KT 120HR VT 15/0600Z 23.0N 67.0W 110 KT NNNN
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Page last modified: Monday, 07-Feb-2005 16:49:58 UTC