934 
 WTPA43 PHFO 110256
 TCDCP3
 
 TROPICAL DEPRESSION ONE-C DISCUSSION NUMBER   1
 NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   CP012009
 500 PM HST MON AUG 10 2009
 
 SATELLITE IMAGERY DURING THE LAST SEVERAL HOURS INDICATES THAT THE
 CONVECTION ASSOCIATED WITH THE DISTURBANCE A COUPLE HUNDRED MILES
 SOUTH-SOUTHWEST OF JOHNSTON ISLAND HAS AQUIRED ENOUGH ORGANIZATION
 TO BE CLASSIFIED AS A TROPICAL DEPRESSION. DVORAK FINAL T NUMBERS 
 FROM PHFO...JTWC...AND SAB WERE A CONSENSUS 2.0 AT 0000 UTC.  IN
 ADDITION...MANUAL ANALYSIS OF THE DIRECTIONAL AMBIGUITIES FROM AN
 EARLIER QUIKSCAT PASS AT 1730 UTC PROVIDES EVIDENCE OF A SURFACE
 CIRCULATION THAT IS COLOCATED WITH THE CLOUD-TOP ROTATION SEEN IN
 GOES IMAGERY.  BASED ON BOTH THE DVORAK CLASSIFCATIONS AND THE 25
 TO 30 KT WIND SPEEDS IN THE QUIKSCAT DATA...THE ADVISORY INTENSITY
 IS SET TO 30 KT.
 
 THE INITIAL MOTION IS 285/12. ONE-C IS TO THE SOUTH OF A LARGE
 SUBTROPICAL RIDGE...AND GLOBAL MODELS FORECAST THE RIDGE TO KEEP IT
 ON A WEST-NORTHWEST TRACK THROUGH ABOUT 48 HOURS. AFTER THAT...THE
 CYCLONE IS EXPECTED TO MAKE A TURN TOWARD THE NORTHWEST AS A
 WEAKNESS IN THE RIDGE AT MID AND UPPER LEVELS DEVELOPS NORTH OF THE
 SYSTEM. THE GLOBAL MODELS ARE IN GOOD AGREEMENT WITH THIS
 SCENARIO...AND THE OFFICIAL FORECAST LIES BETWEEN THE NOGAPS AND
 GFS SOLUTIONS.
 
 THE DEPRESSION IS WELL-SEPARATED FROM OTHER ITCZ CONVECTION AND IS
 EXPECTED TO REMAIN OVER SEA-SURFACE TEMPERATURES NEAR 28 CELSIUS
 OVER THE NEXT FIVE DAYS. IN ADDITION...WEAK SHEAR IS EXPECTED TO
 PERSIST THROUGH THE NEXT 72 HOURS WHICH SHOULD ALLOW THE DEPRESSION
 TO INTENSIFY TO HURRICANE STRENGTH AS FORECAST BY THE SHIPS
 GUIDANCE. IN FACT...THE SHIPS RAPID INTENSIFICATION INDEX INDICATES
 A 75 PERCENT CHANCE OF A 25 KT INCREASE IN THE NEXT 24 HOURS...
 WHICH IS REFLECTED IN THE OFFICIAL FORECAST. BEYOND DAY 3...THE
 CYCLONE IS FORECAST TO ENCOUNTER INCREASING UPPER LEVEL
 SOUTHWESTERLIES AHEAD OF AN UPPER LEVEL TROUGH TO THE NORTH OF THE
 CYCLONE...AND THUS A WEAKENING TREND IS INDICATED BY THE END OF THE
 FORECAST PERIOD.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      11/0300Z 13.7N 170.6W    30 KT
  12HR VT     11/1200Z 14.1N 172.3W    40 KT
  24HR VT     12/0000Z 14.7N 174.5W    55 KT
  36HR VT     12/1200Z 15.3N 176.4W    60 KT
  48HR VT     13/0000Z 15.9N 178.0W    65 KT
  72HR VT     14/0000Z 17.5N 179.5E    70 KT
  96HR VT     15/0000Z 19.5N 177.5E    65 KT
 120HR VT     16/0000Z 21.5N 176.5E    60 KT
  
 $$
 FORECASTER R BALLARD/KNABB