ZCZC MIATCDEP5 ALL TTAA00 KNHC DDHHMM HURRICANE DARBY DISCUSSION NUMBER 11 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 2 AM PDT THU JUL 29 2004 DARBY HAS BEEN AN AMAZING HURRICANE BY RAPIDLY INTENSIFYING FOR THE PAST 54 HOURS BY INCREASING FROM 35 KT TO 105 KT...WITH THE LAST 12 HOURS OF RAPID INTENSIFICATION HAVING OCCURRED OVER SUB-27C SSTS. THE INITIAL INTENSITY OF 105 KT IS BASED ON A SOLID DVORAK SATELLITE INTENSITY ESTIMATE OF T6.0...OR 115 KT...FROM BOTH TAFB AND SAB AND A 29/0229Z AMSU PRESSURE ESTIMATE OF 959 MB. ONLY 90 PERCENT OF THE 115 KT SATELLITE INTENSITY ESTIMATE IS BEING USED SINCE DARBY IS OVER 26C WATER. I FEEL THAT COMPLETE DOWNWARD MIXING OF THE STRONG WINDS TO THE SURFACE IS NOT OCCURRING DUE TO THE COOLER AND MORE STABLE BOUNDARY LAYER. HOWEVER...THIS STILL MAKES DARBY THE FIRST NORTHEAST PACIFIC MAJOR HURRICANE SINCE KENNA BACK IN OCTOBER 2002. THE INITIAL MOTION IS 295/12. SATELLITE FIX POSITIONS HAVE BEEN COMING IN ON TRACK SO THERE REMAINS NO SIGNIFICANT CHANGE TO THE PREVIOUS FORECAST TRACK AND REASONING. THE STRONG RIDGE TO THE NORTH SHOULD KEEP DARBY MOVING ALONG ON A WEST-NORTHWEST TRACK... WITH A GRADUAL TURN TO THE WEST BY 48-72 HOURS AS THE SYSTEM RAPIDLY WEAKENS AND IS STEERED MORE BY THE EASTERLY LOW-LEVEL TRADE WIND FLOW. THE OFFICIAL FORECAST TRACK IS JUST AN EXTENSION OF THE PREVIOUS TRACK AND IS BETWEEN THE GUNS AND GUNA CONSENSUS MODELS. DARBY WILL BE MOVING OVER SUB-25C SSTS IN ABOUT 12 HOURS AND OVER SUB-24C WATER BY 36 HOURS...SO RAPID WEAKENING IS FORECAST TO COMMENCE SHORTLY. THE INTENSITY FORECAST IS CLOSE TO THE SHIPS INTENSITY MODEL...EXCEPT THE SHIPS MODEL COMPLETELY DISSIPATES THE CYCLONE BY 84 HOURS. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 29/0900Z 17.0N 126.8W 105 KT 12HR VT 29/1800Z 17.6N 128.4W 95 KT 24HR VT 30/0600Z 18.3N 130.6W 75 KT 36HR VT 30/1800Z 18.8N 132.8W 60 KT 48HR VT 31/0600Z 19.1N 135.1W 45 KT 72HR VT 01/0600Z 19.5N 140.0W 30 KT...DISSIPATING 96HR VT 02/0600Z 20.0N 145.0W 25 KT...REMNANT LOW 120HR VT 03/0600Z 20.0N 150.5W 25 KT...REMNANT LOW $$ NNNN
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Page last modified: Thursday, 29-Jul-2004 08:22:28 UTC