556 
 WTPZ43 KNHC 080243
 TCDEP3
 HURRICANE FELICIA DISCUSSION NUMBER  18
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP082009
 800 PM PDT FRI AUG 07 2009
  
 SATELLITE IMAGERY...INCLUDING A TRMM OVERPASS...INDICATE THAT
 FELICIA HAS BECOME BETTER ORGANIZED DURING THE PAST SEVERAL HOURS. 
 THE EYE IS MORE DISTINCT...AND THE EYEWALL IS MORE SYMMETRIC WITH
 COLDER CLOUD TOPS.  SATELLITE INTENSITY ESTIMATES ARE 102 KT FROM
 TAFB AND 90 KT FROM SAB.  BASED ON THIS...THE INITIAL INTENSITY IS
 INCREASED TO 90 KT...AND THIS COULD BE A LITTLE CONSERVATIVE.  THE
 HURRICANE REMAINS IN A LIGHT VERTICAL WIND SHEAR ENVIRONMENT WITH
 GOOD CIRRUS OUTFLOW OVER THE WESTERN SEMICIRCLE AND FAIR OUTFLOW
 ELSEWHERE.
 
 THE INITIAL MOTION IS 295/12.  WATER VAPOR IMAGERY AND LARGE-SCALE
 MODEL ANALYSES SUGGEST THAT THE SUBTROPICAL RIDGE IS BUILDING NORTH
 OF FELICIA...WHICH SHOULD CAUSE THE HURRICANE TO TURN GRADUALLY
 WESTWARD DURING THE NEXT 24-36 HR.  AFTER THAT...THE MODELS
 FORECAST FELICIA TO ENCOUNTER INCREASING UPPER-LEVEL WESTERLIES...
 A BREAK IN THE MID-LEVEL RIDGE EAST OF THE HAWAIIAN ISLANDS...AND A
 WEAK MID-LEVEL ANTICYCLONE FORMING JUST SOUTHWEST OF THE ISLANDS. 
 THE MODELS SHOW THIS EVOLUTION BLOCKING THE WESTWARD MOTION OF THE
 MID- AND UPPER-LEVEL PORTIONS OF FELICIA...CAUSING THE STORM TO
 SHEAR APART IN ABOUT 48 HR.  THE WEAKENING LOW-LEVEL CIRCULATION
 WOULD THEN CONTINUE WESTWARD IN THE TRADE WINDS.  ALL MODEL GUIDANCE
 AGREES WITH THIS SCENARIO...AND THE OFFICIAL FORECAST FOLLOWS
 IT...CALLING FOR FELICIA TO PASS NEAR THE ISLAND OF HAWAII BETWEEN
 72-96 HR.  THE NEW FORECAST TRACK IS AN UPDATE OF THE PREVIOUS
 FORECAST AND LIES JUST SOUTH OF THE MODEL CONSENSUS.  AN
 ALTERNATIVE SCENARIO IS FOR FELICIA TO MAINTAIN SOME VERTICAL
 INTEGRITY AND BE STEERED TOWARD THE WEST-SOUTHWEST BY THE MID-LEVEL
 RIDGE NEAR HAWAII.
 
 FELICIA IS STILL MOVING OVER COOLING SEA SURFACE TEMPERATURES...AND
 SHOULD CONTINUE TO DO SO FOR ANOTHER 12-18 HR.  THIS SHOULD CAUSE
 THE HURRICANE TO WEAKEN...THE RECENT INTENSIFICATION
 NOTWITHSTANDING.  WHILE THE SSTS ALONG THE FORECAST INCREASE
 STARTING IN ABOUT 24 HR...THE CYCLONE IS LIKELY TO CONTINUE
 WEAKENING DUE TO THE INCREASED SHEAR BEGINNING IN 36-48 HR.  ALL
 INTENSITY GUIDANCE CALLS FOR WEAKENING AS FELICIA APPROACHES
 HAWAII...AND THE NEW INTENSITY FORECAST FOLLOWS THE GUIDANCE IN
 BEST AGREEMENT WITH THE INTENSITY CONSENSUS MODEL.  IF FELICIA
 MOVES SOUTH OF THE FORECAST TRACK...IT WOULD ENCOUNTER WARMER SSTS
 AND LESS SHEAR...WHICH COULD ALLOW IT TO REMAIN STRONGER THAN
 FORECAST.  ON THE OTHER HAND...ANY MOTION NORTH OF THE FORECAST
 TRACK WOULD STEER THE CYCLONE INTO STRONG SHEAR NORTH OF HAWAII AND
 HASTEN ITS DEMISE.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      08/0300Z 18.8N 138.0W    90 KT
  12HR VT     08/1200Z 19.3N 139.8W    80 KT
  24HR VT     09/0000Z 19.5N 142.4W    70 KT
  36HR VT     09/1200Z 19.6N 145.0W    65 KT
  48HR VT     10/0000Z 19.6N 147.6W    55 KT
  72HR VT     11/0000Z 19.5N 153.0W    35 KT
  96HR VT     12/0000Z 19.5N 159.0W    30 KT
 120HR VT     13/0000Z 20.0N 164.0W    20 KT...REMNANT LOW
  
 $$
 FORECASTER BEVEN