MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 26W (MEARI) WARNING NR 16// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 26W (MEARI), LOCATED APPROXIMATELY 243 NM SOUTHEAST OF IWO TO, JAPAN HAS TRACKED NORTHEASTWARD AT 15 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS AN ASYMMETRIC CONVECTIVE STRUCTURE AS THE SYSTEM HAS STARTED TO ELONGATE TO THE NORTHEAST DUE TO THE STRONG SOUTHWESTERLY VERTICAL WIND SHEAR ASSOCIATED WITH THE MID-LATITUDE WESTERLY FLOW. A 060856Z GPM 89GHZ MICROWAVE IMAGE SHOWS A SMALL CONVECTIVE CORE THAT HAS SLIGHTLY ERODED BUT STILL SURROUNDS A SMALL MICROWAVE EYE FEATURE. THE CURRENT POSITION IS PLACED WITH FAIR CONFIDENCE UNDER THE CENTRAL CONVECTION WITHIN THE CENTER OF A PARTIAL ASCAT PASS. THE INTENSITY HAS BEEN HELD AT 90 KNOTS BASED ON DVORAK CURRENT INTENSITY ESTIMATES THAT REMAIN AT T5.0 (90 KNOTS). A STRONG POLEWARD OUTFLOW IS SUSTAINING THE CURRENT CONVECTION AND OFFSETTING THE HIGH (25-30 KNOT) VERTICAL WIND SHEAR (VWS) THAT IS IN-PHASE WITH THE STORM MOTION. TY 26W IS TRACKING NORTHEASTWARD ALONG THE WESTERN PERIPHERY OF THE DEEP-LAYERED SUBTROPICAL RIDGE (STR). 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY MEARI IS EXPECTED TO CONTINUE TRACKING NORTHEASTWARD TO NORTH-NORTHEASTWARD THROUGHOUT THE FORECAST PERIOD ALONG THE WESTERN PERIPHERY OF THE STEERING STR. TY 26W SHOULD MAINTAIN INTENSITY OVER THE NEXT 12 HOURS BUT HAS MOST LIKELY REACHED ITS PEAK INTENSITY. BEYOND TAU 12, INCREASING VWS ASSOCIATED WITH THE APPROACHING MID- LATITUDE TROUGH WILL BEGIN THE RAPID WEAKENING PHASE. TY MEARI WILL BEGIN EXTRA-TROPICAL TRANSITION (ETT) IN THE NEXT 24 HOURS AS IT INTERACTS WITH THE BAROCLINIC ZONE AND EMBEDS UNDER THE MID-LATITUDE WESTERLY FLOW. VWS ASSOCIATED WITH THE STRONG WESTERLIES WILL BECOME INCREASINGLY UNFAVORABLE AS THE SYSTEM GAINS LATITUDE. THE TYPHOON WILL GAIN FRONTAL CHARACTERISTICS AND COMPLETE ETT AS A STRONG COLD- CORE LOW BY THE END OF THE FORECAST PERIOD. DYNAMIC MODEL GUIDANCE REMAINS IN TIGHT AGREEMENT, THEREFORE, THERE IS HIGH CONFIDENCE IN THE JTWC TRACK FORECAST.// NNNN NNNN