MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 23W (SONGDA) WARNING NR 16// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 23W (SONGDA), LOCATED APPROXIMATELY 618 NM EAST- SOUTHEAST OF YOKOSUKA, JAPAN, HAS TRACKED EAST-NORTHEASTWARD AT 19 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THAT THE SYSTEM HAS STARTED TO SHOW THE EFFECTS OF THE HIGH VERTICAL WIND SHEAR (VWS) ASSOCIATED WITH THE STRONG MID- LATITUDE WESTERLIES. THE STRUCTURE HAS STARTED TO ELONGATE TO THE NORTHEAST AND THE EYE IS CLOUD FILLED IN VISIBLE SATELLITE IMAGERY. AN 112058Z SSMIS 91GHZ MICROWAVE IMAGE DEPICTS A MORE RAGGED CORE STRUCTURE; HOWEVER, A DEEP CONVECTIVE RING STILL SURROUNDS THE EYE FEATURE. THE CURRENT POSITION IS BASED ON THE 22-NM EYE IN THE MSI IMAGERY. THE INTENSITY HAS BEEN DECREASED TO 120 KNOTS BASED ON AN ASSESSMENT OF DECREASING DVORAK INTENSITY ESTIMATES FROM ALL AGENCIES. ENVIRONMENTAL CONDITIONS CONTINUE TO DETERIORATE DUE PRIMARILY TO THE AFOREMENTIONED HIGH VWS. TY 23W IS TRACKING NORTHEASTWARD ALONG THE NORTHERN PERIPHERY OF THE DEEP-LAYERED SUB- TROPICAL RIDGE. 3. FORECAST REASONING. A. NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY SONGDA WILL CONTINUE ACCELERATING NORTHEASTWARD AS IT EMBEDS DEEPER WITHIN THE MID-LATITUDE WESTERLY FLOW. THE CYCLONE STRUCTURE WILL CONTINUE TO ELONGATE AND WEAKEN AS IT ENCOUNTERS VWS OVER 40 KNOTS AND COOLING SEA SURFACE TEMPERATURES. TY SONGDA WILL BEGIN EXTRA-TROPICAL TRANSITION (ETT) OVER THE NEXT 12 HOURS AND COMPLETE ETT BY THE END OF THE FORECAST PERIOD. DYNAMIC MODEL GUIDANCE REMAINS IN TIGHT AGREEMENT LENDING HIGH CONFIDENCE TO THE FORECAST TRACK.// NNNN NNNN