508 
 WTPZ42 KNHC 251444
 TCDEP2
 TROPICAL STORM IGNACIO DISCUSSION NUMBER   4
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP122009
 800 AM PDT TUE AUG 25 2009
  
 THE CLOUD PATTERN OF IGNACIO APPEARS DISORGANIZED...WITH THE CENTER
 LOCATED NEAR THE NORTHERN EDGE OF AN AMORPHOUS MASS OF VERY DEEP
 CONVECTION.  WHILE THE UPPER-LEVEL OUTFLOW IS FAIRLY
 WELL-ESTABLISHED IN THE SOUTHERN SEMICIRCLE...IT REMAINS SOMEWHAT
 RESTRICTED TO THE NORTH.  DVORAK T-NUMBERS HAVE INCREASED TO
 T3.0 FROM TAFB AND SAB AND THE OFFICIAL INTENSITY IS SET AT 45 KT. 
 IGNACIO STILL HAS AN OPPORTUNITY TO STRENGTHEN DURING THE NEXT
 12-24 HOURS WHILE IT TRACKS OVER WARM WATERS AND ENCOUNTERS
 RELATIVELY WEAK SHEAR. THEREAFTER...THE CYCLONE SHOULD REACH
 SIGNIFICANTLY COOLER WATERS AND QUICKLY WEAKEN TO A REMNANT LOW BY
 72 HOURS.
  
 A 1158 UTC TRMM PASS WAS HELPFUL IN LOCATING THE CENTER.  WHILE
 STILL UNCERTAIN...THE INITIAL MOTION ESTIMATE IS 295/10.  THE
 FORECAST TRACK PHILOSOPHY HAS NOT CHANGED.  IGNACIO IS ON THE
 SOUTHWEST SIDE OF A DEEP-LAYER ANTICYCLONE EXTENDING FROM THE
 SOUTHERN UNITED STATES INTO THE EAST PACIFIC TO NEAR 130W.  A WEAK
 SHORTWAVE TROUGH SHOULD LIFT NORTHEAST AHEAD OF A DEEPENING EAST
 PACIFIC/GULF OF ALASKA LONGWAVE TROUGH...KEEPING A WEAKNESS IN THE
 SUBTROPICAL RIDGE IN PLACE ALONG 130W.  THIS SHOULD HELP STEER
 IGNACIO ON A NORTHWESTERLY COURSE DURING THE NEXT FEW DAYS. TOWARD
 THE END OF THE PERIOD...THE CYCLONE SHOULD ASSUME A MORE WESTERLY
 TRACK ONCE IGNACIO WEAKENS AND BECOMES MORE SHALLOW.  THE OFFICIAL
 TRACK DIFFERS LITTLE FROM THE PREVIOUS ADVISORY AND IS IN GOOD
 AGREEMENT WITH THE MODEL CONSENSUS.
   
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      25/1500Z 18.6N 119.3W    45 KT
  12HR VT     26/0000Z 19.4N 120.8W    50 KT
  24HR VT     26/1200Z 20.8N 122.8W    50 KT
  36HR VT     27/0000Z 22.3N 124.6W    45 KT
  48HR VT     27/1200Z 24.0N 126.5W    35 KT
  72HR VT     28/1200Z 26.5N 129.5W    25 KT...REMNANT LOW
  96HR VT     29/1200Z 27.0N 133.0W    20 KT...REMNANT LOW
 120HR VT     30/1200Z...DISSIPATED
  
 $$
 FORECASTER KIMBERLAIN/WALTON