067 
 WTPA45 PHFO 240243
 TCDCP5
 
 TROPICAL STORM ANA DISCUSSION NUMBER  42
 NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   CP022014
 500 PM HST THU OCT 23 2014
  
 THE LATEST SUBJECTIVE DVORAK CURRENT INTENSITY ESTIMATES RANGE FROM 
 2.0/30 KT TO 2.5/35 KT...BUT OTHER DATA SOURCES SUGGEST THESE 
 ESTIMATES ARE TOO LOW. MOST RECENT OBJECTIVELY-BASED SATELLITE 
 INTENSITY ESTIMATES FROM UW-CIMSS SUGGEST AN INTENSITY NEAR 45 
 KT...WHILE A 2128Z ASCAT PASS SQUARELY SAMPLED THE WIND FIELD 
 ASSOCIATED WITH ANA...WITH WINDS AS HIGH AS 40 KT DETECTED. AS 
 ASCAT HAS A KNOWN LOW BIAS AT THESE WIND SPEEDS...THE INITIAL 
 INTENSITY FOR THIS PACKAGE WILL REMAIN 45 KT. BASED ON THE ASCAT 
 DATA...WIND RADII FOR THIS PACKAGE HAVE BEEN REDUCED.
 
 ALTHOUGH THE PREVIOUS TRACK FORECAST SLOWED THE SHORT TERM
 MOTION...ANA HAS BEEN MOVING EVEN MORE SLOWLY THAN THAT TODAY...WITH 
 THE INITIAL MOTION VECTOR ESTIMATED TO BE 320/06 KT. OVERALL HOWEVER 
 THE TRACK FORECAST REASONING REMAINS CONSISTENT...WITH A GRADUAL 
 TURN TO THE NORTH AND AN INCREASE IN FORWARD SPEED EXPECTED TONIGHT 
 INTO FRIDAY. THIS WILL OCCUR AS A MID-LEVEL RIDGE EXTENDING 
 NORTHWESTWARD FROM AN ANTICYCLONE CENTERED EAST OF ANA BEGINS TO 
 FLATTEN...AND ANA MOVES NORTH OF THE ANTICYCLONE. A RAPID 
 ACCELERATION TOWARD THE NORTHEAST IS ANTICIPATED FRIDAY NIGHT AND 
 SATURDAY...AS ANA GETS CAUGHT UP IN STRONG MID-LATITUDE WESTERLIES. 
 EXTRATROPICAL TRANSITION IS EXPECTED TO BEGIN IN 48 HOURS...WITH ANA 
 COMPLETING THE TRANSITION BY DAY 3...THEN BECOMING ABSORBED BY A 
 STRONG EXTRATROPICAL LOW APPROACHING BRITISH COLUMBIA BY DAY 4. THIS 
 IS CONSISTENT WITH RECENT ECMWF SOLUTIONS AND GUIDANCE SUPPLIED BY 
 THE OCEAN PREDICTION CENTER. THIS FORECAST DISCOUNTS RECENT GFS 
 SOLUTIONS WHICH KEEP THE EXTRATROPICAL VERSION OF ANA AS A 
 SEPARATE ENTITY...AND DO NOT SHOW ABSORPTION INTO ANOTHER LOW.
 
 WHILE ANA IS EXPECTED TO MOVE OVER INCREASINGLY COOLER WATERS...
 VERTICAL SHEAR IS EXPECTED TO REMAIN CONDUCIVE FOR MODEST 
 STRENGTHENING AS A TROPICAL LOW IN THE SHORT TERM. AS ANA 
 TRANSITIONS TO AN EXTRATROPICAL LOW...BAROCLINIC PROCESSES ARE 
 EXPECTED TO ALLOW ANA TO MAINTAIN STRENGTH...WITH WIND RADII 
 EXPANDING RAPIDLY AS THIS OCCURS...PER LATEST OPC GUIDANCE.
  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  24/0300Z 27.2N 170.2W   45 KT  50 MPH
  12H  24/1200Z 28.6N 170.1W   50 KT  60 MPH
  24H  25/0000Z 30.8N 168.8W   50 KT  60 MPH
  36H  25/1200Z 33.8N 165.6W   50 KT  60 MPH
  48H  26/0000Z 37.5N 160.0W   50 KT  60 MPH
  72H  27/0000Z 46.5N 145.5W   50 KT  60 MPH...POST-TROP/EXTRATROP
  96H  28/0000Z...ABSORBED
  
 $$
 
 FORECASTER BIRCHARD