000 WTPZ43 KNHC 080839 TCDEP3 HURRICANE FELICIA DISCUSSION NUMBER 19 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP082009 200 AM PDT SAT AUG 08 2009 INFRARED SATELLITE IMAGERY SUGGESTS THAT THE BRIEF INTENSIFICATION OBSERVED EARLIER IS LIKELY NOW OVER...AND A GRADUAL...WEAKENING SEEMS TO HAVE COMMENCED. THIS IS EVIDENCED BY CLOUD TOP TEMPERATURES THAT HAVE BEEN WARMING...AND A NOTABLE DRY SLOT THAT HAS BEEN ROTATING NORTH OF THE CENTER. HOWEVER...FELICIA HAS BEEN EXHIBITING MANY OF THE COMMON CHARACTERISTICS OF AN ANNULAR HURRICANE...INCLUDING A FAIRLY UNIFORM RING OF DEEP CONVECTION SURROUNDING THE CENTER AND A LACK OF DEEP CONVECTIVE FEATURES OUTSIDE OF THIS AREA. ON THE BASIS OF THE DEGRADED SATELLITE APPEARANCE AND DVORAK CURRENT INTENSITY ESTIMATES OF 4.5 AND 5.0...THE INTENSITY IS LOWERED TO 80 KT THIS ADVISORY. THE INITIAL MOTION ESTIMATE IS 285/12...BUT THE LAST FEW SATELLITE PICTURES INDICATE THAT THE HEADING MAY ACTUALLY BE EVEN MORE WESTWARD. FELICIA IS IN THE PROCESS OF MAKING A GRADUAL TURN TOWARD THE WEST IN RESPONSE TO A BUILDING MID-LEVEL RIDGE NORTH OF THE CYCLONE...WHICH SHOULD CAUSE IT TO GAIN LITTLE LATITUDE BEYOND 24 HOURS. A WEAKER FELICIA LATER IN THE FORECAST SHOULD CONTINUE ON A MOSTLY DUE-WESTWARD COURSE WITHIN THE TRADE WIND FLOW. OUTSIDE OF THE GFS AND THE CANADIAN MODEL...WHICH SHOW A MORE NORTHERN TRACK...THE DYNAMICAL MODEL GUIDANCE FAVORS THIS SCENARIO AND IS FAIRLY TIGHTLY CLUSTERED ON A TRACK PASSING CLOSE TO THE ISLAND OF HAWAII JUST AFTER 72 HOUR. THE NEW FORECAST TRACK REPRESENTS AN UPDATE OF THE PREVIOUS FORECAST AND LIES SLIGHTLY SOUTH OF THE MODEL CONSENSUS IN AN EFFORT TO MINIMIZE THE CONTRIBUTION BY THE GFS AND CANADIAN MODEL OUTPUT. FELICIA HAS BEEN MOVING OVER COOLING SEA SURFACE TEMPERATURES DURING THE LAST 24 HOURS...BUT WATER TEMPERATURES ARE PREDICTED TO SLOWLY WARM ALONG THE FORECAST TRACK. HOWEVER...WESTERLY VERTICAL WIND SHEAR SHOULD ABRUPTLY INCREASE AROUND 48 HOURS IN ASSOCIATION WITH A CLOSED MID- TO UPPER-LEVEL CYCLONE NORTH OF THE HAWAIIAN ISLANDS. ALL INTENSITY GUIDANCE CALLS FOR A GRADUAL WEAKENING OVER THE NEXT DAY OR TWO...FOLLOWED BY AN ACCELERATED WEAKENING IN RESPONSE TO THE INCREASING WESTERLY SHEAR. SHOULD FELICIA ASSUME A MOTION SOUTH OF THE FORECAST TRACK...IT WOULD LIKELY ENCOUNTER A LOWER SHEAR ENVIRONMENT AND BE STRONGER THAN FORECAST. ON THE OTHER HAND...A MOTION NORTH OF THE FORECAST TRACK WOULD LEAD FELICIA INTO EVEN HIGHER SHEAR AND WOULD RESULT IN A FASTER WEAKENING. FORECAST POSITIONS AND MAX WINDS INITIAL 08/0900Z 19.0N 139.3W 80 KT 12HR VT 08/1800Z 19.3N 141.2W 70 KT 24HR VT 09/0600Z 19.5N 143.8W 65 KT 36HR VT 09/1800Z 19.6N 146.4W 55 KT 48HR VT 10/0600Z 19.5N 149.0W 50 KT 72HR VT 11/0600Z 19.5N 154.5W 35 KT 96HR VT 12/0600Z 19.5N 159.5W 30 KT 120HR VT 13/0600Z 20.0N 165.0W 25 KT...REMNANT LOW $$ FORECASTER KIMBERLAIN/AVILA