050900Z POSITION NEAR 37.0N 133.6E. TROPICAL STORM 21W (CHABA), LOCATED APPROXIMATELY 121 NM NORTH- NORTHWEST OF IWAKUNI, JAPAN, HAS TRACKED NORTHEASTWARD AT 34 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A FULLY EXPOSED AND EXPANDING LOW LEVEL CIRCULATION CENTER (LLCC) WITH VIRTUALLY NO BANDING FEATURES REMAINING. A 050636Z SSMIS 91 GHZ IMAGE SHOWS THE BULK OF CONVECTION BEING SHEARED TO THE NORTHEAST OF A VERY BROAD AND ELONGATED LOW LEVEL FEATURE, GIVING LOW CONFIDENCE TO THE INITIAL POSITION. THE SYSTEM IS ALSO SHOWING SIGNIFICANT FRONTAL FEATURES AT THIS TIME AS OBSERVED FROM RECENT JMA RADAR IMAGERY. THE INITIAL INTENSITY IS ASSESSED AT 50 KNOTS AND BASED ON THE DETERIORATING CONVECTIVE STRUCTURE AND THE LOWER END OF DVORAK ESTIMATES RANGING FROM T3.0 TO T5.0 (45 TO 90 KNOTS RESPECTIVELY). THE LLCC WAS OBSERVED IN SATELLITE IMAGERY TO HAVE RECENTLY SKIRTED THE COAST OF SOUTH KOREA, DISRUPTING THE LOW LEVEL FLOW AND AIDING IN THE RAPID WEAKENING. SUSTAINED WIND VALUES OF 45 KNOTS WERE OBSERVED FROM BUSAN, SOUTH KOREA AS THE LLCC PASSED CLOSE BY. TS CHABA IS NEARLY FULLY EMBEDDED IN THE BAROCLINIC ZONE, MAKING THE TRANSITION INTO AN EXTRATROPICAL SYSTEM. BY TAU 12 TS CHABA IS EXPECTED TO BE FULLY EXTRATROPICAL. THIS IS THE FINAL WARNING ON THIS SYSTEM BY THE JOINT TYPHOON WRNCEN PEARL HARBOR HI. THE SYSTEM WILL BE CLOSELY MONITORED FOR SIGNS OF REGENERATION. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 050600Z IS 12 FEET.
