000 WTPZ43 KNHC 070835 TCDEP3 HURRICANE FELICIA DISCUSSION NUMBER 15 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP082009 200 AM PDT FRI AUG 07 2009 INFRARED AND MICROWAVE SATELLITE IMAGERY INDICATE THAT THE CLOUD PATTERN ASSOCIATED WITH FELICIA HAS SUBSTANTIALLY DETERIORATED DURING THE LAST 6 HOURS. MOREOVER...CLOUD TOP TEMPERATURES HAVE WARMED CONSIDERABLY AND THE CONVECTIVE ORGANIZATION HAS BECOME ASYMMETRIC. DVORAK T-NUMBERS HAVE DECREASED TO 5.0 FROM BOTH TAFB AND SAB. THE INTENSITY IS THEREFORE BEING REDUCED TO 100 KT ON THIS ADVISORY...THOUGH THIS MAY BE SOMEWHAT GENEROUS GIVEN RECENT TRENDS. THE INITIAL MOTION IS ESTIMATED AT 300/9...THE SAME MOTION THAT HAS PERSISTED WITH LITTLE DEVIATION FOR THE LAST 48 HOURS. AT THE MOMENT...FELICIA IS TRACKING TOWARD A WEAKNESS IN THE MID-LEVEL SUBTROPICAL RIDGE LYING NORTH OF THE HAWAIIAN ISLANDS. HOWEVER... THIS FEATURE IS EXPECTED TO LIFT NORTHWESTWARD DURING THE NEXT DAY OR TWO AS STRONGER SUBTROPICAL RIDGING BUILDS NORTH OF THE CYCLONE AND CAUSES FELICIA TO TURN MORE TOWARD THE WEST-NORTHWEST. THEREAFTER...GLOBAL MODELS DEPICT A WEAKER FELICIA...LIKELY A MORE SHALLOW SYSTEM...BEING STEERED WESTWARD AND EVENTUALLY WEST- SOUTHWESTWARD IN THE LOW-LEVEL TRADE WIND FLOW. THE MODEL CONSENSUS HAS TRENDED SLIGHTLY SOUTHWARD THIS CYCLE BEYOND 24 HOURS...AND THE OFFICIAL FORECAST FOLLOWS SUIT. FELICIA IS FORECAST TO REMAIN IN A LOW SHEAR ENVIRONMENT FOR THE NEXT DAY OR TWO...WITH THE MAIN CONTROLLING FACTOR ON INTENSITY LIKELY TO BE A GRADUAL DECREASE IN SEA SURFACE TEMPERATURES ALONG THE PATH OF THE CYCLONE. BEYOND 48 HOURS...INCREASING WESTERLY SHEAR...ASSOCIATED WITH THE WEAKNESS IN THE SUBTROPICAL RIDGE NOTED ABOVE...SHOULD ACCELERATE THE CURRENT WEAKENING TREND IN SPITE OF MARGINALLY WARMER SEA SURFACE TEMPERATURES WEST OF 150W. SHOULD FELICIA MOVE LEFT OF THE FORECAST TRACK BEYOND 48 HOURS...THERE IS SOME CHANCE THAT THE RATE OF WEAKENING COULD BE SLOWER THAN FORECAST. FORECAST POSITIONS AND MAX WINDS INITIAL 07/0900Z 17.5N 134.4W 100 KT 12HR VT 07/1800Z 18.2N 135.7W 85 KT 24HR VT 08/0600Z 19.0N 137.7W 70 KT 36HR VT 08/1800Z 19.4N 140.1W 60 KT 48HR VT 09/0600Z 19.6N 142.7W 50 KT 72HR VT 10/0600Z 19.5N 148.0W 35 KT 96HR VT 11/0600Z 19.0N 153.5W 25 KT 120HR VT 12/0600Z 19.0N 159.0W 20 KT...REMNANT LOW $$ FORECASTER KIMBERLAIN/AVILA