MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 20W (HAGIBIS) WARNING NR 021// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUPER TYPHOON (STY) 20W (HAGIBIS), LOCATED APPROXIMATELY 654 NM SOUTH OF YOKOSUKA, JAPAN, HAS TRACKED NORTH-NORTHWESTWARD AT 13 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THE SYSTEM HAS MAINTAINED A SHARPLY-OUTLINED 20NM EYE. BASED ON THE MSI LOOP, STY 20W HAS RETURNED FROM A MOMENTARY NORTHWARD TROCHOIDAL JOG, TYPICAL OF VERY INTENSE CYCLONES. THE INITIAL POSITION IS BASED ON THE EYE FEATURE THAT IS NOW VERTICALLY STACKED. THE INITIAL INTENSITY OF 140KTS IS BASED ON CONGRUENT AND NEAR-CONCENTRIC DVORAK ESTIMATES OF T7.0/140KTS FROM PGTW, RJTD, AND RCTP. UPPER LEVEL ANALYSIS INDICATES LOW (05-10KT) VERTICAL WIND SHEAR (VWS) AND STRONG RADIAL OUTFLOW WITH THE POLEWARD CHANNEL GREATLY ENHANCED BY JET WINDS AHEAD OF A SHORTWAVE TROUGH DIGGING IN FROM THE NORTHWEST. ALONG TRACK SST VALUES (28-29C) ARE ALSO CONDUCIVE. THE CYCLONE IS TRACKING ALONG THE WESTERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE EAST. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. STY HAGIBIS WILL CONTINUE ON ITS CURRENT TRACK, STEERED BY THE STR, THROUGH TAU 36. AFTERWARD, IT WILL CREST THE STR AXIS AND ACCELERATE NORTHEASTWARD ON THE POLEWARD SIDE, MAKING A QUICK LANDFALL NEAR YOKOSUKA VIA SAGAMI WAN SHORTLY AFTER TAU 48 BEFORE EXITING BACK INTO THE PACIFIC OCEAN. BY TAU 72, THE CYCLONE WILL BE SOUTHEAST OF HOKKAIDO. THE AFOREMENTIONED FAVORABLE CONDITIONS WILL PERSIST AND SUSTAIN THE CURRENT INTENSITY UP TO TAU 12. AFTERWARD, A GRADUAL WEAKENING TREND DUE TO INCREASING VWS AND SUBSIDENCE ASSOCIATED WITH THE APPROACHING SHORTWAVE TROUGH WILL COMMENCE. BY TAU 48, STY 20W WILL BEGIN EXTRA-TROPICAL TRANSITION AS IT ENTERS THE BAROCLINIC ZONE AND BY TAU 72, WILL TRANSFORM INTO A COLD CORE LOW WITH NEAR-HURRICANE FORCE WINDS AND A VERY EXPANSIVE WIND FIELD WITH FRONTAL CHARACTERISTICS. THE JTWC FORECAST TRACK IS PLACED NEAR BUT SLIGHTLY FASTER THAN THE MULTI-MODEL CONSENSUS AFTER TAU 48. THE NUMERICAL MODELS ARE IN TIGHT AGREEMENT, LENDING HIGH CONFIDENCE IN THE JTWC TRACK FORECAST.// NNNN NNNN