MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 20W (HAGIBIS) WARNING NR 015// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUPER TYPHOON (STY) 20W (HAGIBIS), LOCATED APPROXIMATELY 337 NM SOUTH OF IWO TO, HAS TRACKED NORTHWESTWARD AT 12 KNOTS (KTS) OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THE NEWLY FORMED PRIMARY EYEWALL CONTRACTING INTO A FAIRLY SYMMETRIC, 20 NM DIAMETER EYE WHILE A BROAD AREA OF CONVECTIVE BANDING CONTINUES TO WRAP TIGHTLY INTO THE SYSTEMS CENTER. THERE IS GOOD CONFIDENCE IN THE INITIAL POSITION. A 081932Z SSMIS 91GHZ MICROWAVE IMAGE INDICATES THAT THE EYEWALL REPLACEMENT CYCLE (ERC) IS COMPLETE AND THAT THE PREVIOUS EYEWALL HAS FULLY DISSIPATED. BASED ON THE IMPROVED CONVECTIVE STRUCTURE AND DVORAK CURRENT INTENSITY (CI) ESTIMATES OF T6.5/127 KTS FROM PGTW, T7.0/140 KTS FROM RJTD, AND T6.9/137 KTS FROM ADVANCED DVORAK TECHNIQUE (ADT), THE INITIAL INTENSITY ESTIMATE IS SET AT 140 KTS, FURTHER CORROBORATED BY THE SATELLITE CONSENSUS INTENSITY ESTIMATE. UPPER-LEVEL ANALYSIS SHOWS SUSTAINED STRONG RADIAL OUTFLOW, ENHANCED TOWARDS THE EAST AND SOUTH. AN AREA OF DRY AIR WITH HIGH VERTICAL WIND SHEAR (VWS) TO THE NORTH OF THE SYSTEM IS INHIBITING DEVELOPMENT OF A STRONG POLEWARD OUTFLOW CHANNEL. WITH LOW (05-10 KTS) VWS AND WARM (29-31 CELSIUS) SEA SURFACE TEMPERATURES (SST), STY 20W REMAINS IN A FAVORABLE ENVIRONMENT FOR DEVELOPMENT. STY 20W IS TRACKING NORTHWESTWARD UNDER THE STEERING INFLUENCE OF A SUBTROPICAL RIDGE (STR) TO THE NORTHEAST. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE LAST PROGNOSTIC REASONING MESSAGE. B. AFTER TAU 24, A PASSING MIDLATITUDE TROUGH TO THE NORTH WILL CAUSE THE STR TO RE-ORIENT, ALLOWING STY 20W TO TURN TO A MORE NORTH-NORTHWESTWARD TRACK AS IT ROUNDS THE RIDGE AXIS. WITH LOW VWS, HIGH SST, AND GOOD UPPER-LEVEL OUTFLOW, THE FAVORABLE ENVIRONMENT IS EXPECTED TO PERSIST. THE OFFICIAL INTENSITY FORECAST REMAINS MORE AGGRESSIVE THAN MULTI-MODEL INTENSITY GUIDANCE DUE TO THE POSSIBILITY OF SLIGHT RE-INTENSIFICATION AS THE NEW EYE MAY CONTRACT FURTHER. ADDITIONALLY, THERE MAY BE A BRIEF PERIOD OF ENHANCED POLEWARD OUTFLOW DUE TO TROUGH INTERACTION. AFTERWARDS, GRADUAL WEAKENING IS EXPECTED AS THE OUTFLOW BEGINS TO BE SHEARED BY THE TROUGH. GFS AND THE GFS ENSEMBLE REMAIN THE EASTERNMOST OUTLIERS WHILE THE NAVGEM AND AFUM SOLUTIONS ARE THE WESTERNMOST OUTLIERS, CREATING VARIATION IN THE TIMING OF THE RECURVE. THE OFFICIAL JTWC FORECAST IS PLACED NEAR THE MULTI-MODEL CONSENSUS, LENDING GOOD CONFIDENCE TO THIS PORTION OF THE TRACK. C. IN THE EXTENDED PERIOD, A SHORTWAVE TROUGH OVER JAPAN WILL MOVE THROUGH THE AREA, AGAIN ERODING THE STR AND ALLOWING STY 20W TO RECURVE AFTER TAU 72. THE SYSTEM WILL SLOWLY WEAKEN IN RESPONSE TO INCREASING VWS AFTER TAU 72, OFFSETTING THE OTHERWISE FAVORABLE ENVIRONMENT. AS STY 20W APPROACHES HONSHU, LAND INTERACTION MAY BEGIN TO ERODE THE SYSTEMS INTENSITY. AT TAU 120, AS STY 20W BEGINS INTERACTING WITH THE BAROCLINIC ZONE, THE SYSTEM WILL ACCELERATE TO THE NORTHEAST AND BEGIN EXTRATROPICAL TRANSITION. THROUGHOUT THE EXTENDED FORECAST PERIOD, CROSS-TRACK AGREEMENT IS GOOD, WITH APPROXIMATELY 180 NM OF SPREAD. HOWEVER, THE TIMING OF THE RECURVE AND EXTRATROPICAL TRANSITION VARY BETWEEN MODELS; THUS, THERE IS 700 NM OF ALONG TRACK SPREAD AT TAU 120, WITH NAVGEM REMAINING THE SLOWEST AND MOST WESTWARD MODEL, AND GFS, THE GFS ENSEMBLE, AND JGSM SIGNIFICANTLY FASTER THAN AND EAST OF THE MULTI-MODEL CONSENSUS. THE JTWC FORECAST TRACK IS SHIFTED SLIGHTLY WESTWARD TO BE PLACED NEAR THE MULTI-MODEL CONSENSUS. BASED ON THE VARIATION IN MODEL TIMING OF THE RECURVE AND ALONG-TRACK SPEEDS, THERE IS LOW CONFIDENCE IN THIS PORTION OF THE JTWC TRACK FORECAST.// NNNN NNNN