MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 23W (CHOI-WAN) WARNING NR 19// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 23W (CHOI-WAN), LOCATED APPROXIMATELY 864 NM SOUTHEAST OF MISAWA, JAPAN, HAS TRACKED NORTHWARD AT 19 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A GENERAL WEAKENING TREND CORRESPONDING TO INCREASING SOUTHWESTERLY VERTICAL WIND SHEAR (VWS). THIS TREND IS EVIDENT IN A 062154Z SSMIS 91GHZ IMAGE, WHICH SHOWS DEEP CONVECTION WRAPPING BROADLY INTO AN ELONGATED LOW-LEVEL CIRCULATION CENTER (LLCC). THE CURRENT POSITION IS BASED ON THE SSMIS 37GHZ IMAGE WITH GOOD CONFIDENCE. THE INITIAL INTENSITY HAS BEEN REDUCED TO 65 KNOTS BASED ON DVORAK CURRENT INTENSITY ESTIMATES OF 65 KNOTS (T4.0). UPPER- LEVEL ANALYSIS DEPICTS A VIGOROUS POLEWARD OUTFLOW CHANNEL ASSOCIATED WITH A DEEP TROUGH ENTRENCHED SOUTH OF JAPAN. TY 23W IS CURRENTLY TRACKING ALONG THE WESTERN PERIPHERY OF A DEEP, POLEWARD-ORIENTED STR. 3. FORECAST REASONING. A. NO CHANGE TO FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY CHOI-WAN WILL CONTINUE TO ACCELERATE NORTHWARD THROUGH THE FORECAST PERIOD. TY 23W APPEARS TO HAVE PEAKED BUT WILL WEAKEN SLOWLY THROUGH TAU 12 AS VWS WILL BE OFFSET BY THE STRONG POLEWARD OUTFLOW. TY 23W HAS COMMENCED EXTRA-TROPICAL TRANSITION (ETT) AS IT BEGINS TO INTERACT WITH THE BAROCLINIC ZONE AND WILL COMPLETE ETT BY TAU 36 AS IT GAINS FRONTAL CHARACTERISTICS AND BECOMES EMBEDDED WITHIN THE MIDLATITUDE WESTERLIES. THE SYSTEM IS EXPECTED TO MAINTAIN STORM FORCE WINDS AND EXPANSIVE GALE-FORCE WINDS, WHICH COULD ENCROACH ON THE COASTAL REGIONS OF NORTHERN JAPAN. DYNAMIC MODEL GUIDANCE REMAINS IN VERY TIGHT AGREEMENT THROUGHOUT THE FORECAST PERIOD LEADING TO HIGH CONFIDENCE IN THE JTWC TRACK FORECAST.// NNNN NNNN