MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 20W (HAGIBIS) WARNING NR 020// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUPER TYPHOON (STY) 20W (HAGIBIS), LOCATED APPROXIMATELY 726 NM SOUTH OF YOKOSUKA, JAPAN, HAS TRACKED NORTHWARD AT 12 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY REVEALS A 23 NM ROUND EYE, WHICH SUPPORTS THE INITIAL POSITION WITH GOOD CONFIDENCE. ADDITIONALLY, EIR IMAGERY INDICATES TROCHOIDAL MOTION OVER THE PAST 12 HRS. A 092124Z SSMIS 91GHZ IMAGE DEPICTS A WELL-DEFINED MICROWAVE EYE AND ALSO INDICATES THAT THE OUTER EYEWALL HAS ERODED EXCEPT OVER THE EASTERN SEMICIRCLE. THE INITIAL INTENSITY IS BASED ON DVORAK CURRENT INTENSITY ESTIMATES OF 7.0 (140 KTS) FROM PGTW AND RJTD. FURTHERMORE, THERE IS A 092042Z SMAP IMAGE (40 KM RESOLUTION) WITH MAX WIND SPEEDS OF 129 KTS (1-MINUTE AVERAGE) THAT SUPPORTS THE CURRENT INTENSITY ESTIMATE. STY 20W HAS STRONG RADIAL OUTFLOW; THE POLEWARD OUTFLOW IS BEING FURTHER ENHANCED BY A TROUGH TO THE NORTHWEST OF THE SYSTEM. FURTHERMORE, THE SYSTEM IS SITTING IN FAVORABLE ENVIRONMENTAL CONDITIONS WITH WARM SST VALUES (28-29C) AND LOW VERTICAL WIND SHEAR (VWS). STY 20W IS TRACKING NORTHWARD ALONG THE WESTERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE POSITIONED TO THE EAST. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. WIND RADII HAVE BEEN ADJUSTED SLIGHTLY BASED ON THE SMAP DATA--THIS DATA CONTINUES TO INDICATE AN EXPANSIVE GALE WIND FIELD. B. STY 20W WILL TRACK NORTH-NORTHWESTWARD ALONG THE WESTERN PERIPHERY OF THE DEEP-LAYERED STR THROUGH TAU 36. STY 20W IS EXPECTED TO BEGIN A GRADUAL WEAKENING TREND BY TAU 24 DUE TO INCREASING VWS AND CONVERGENCE ASSOCIATED WITH THE MIDLATITUDE TROUGH. AFTER TAU 36, STY 20W WILL BEGIN RECURVING NORTHWARD TO NORTH-NORTHEASTWARD AS IT ROUNDS THE STR AND BEGINS EXTRA- TROPICAL TRANSITION (ETT). AFTER TAU 60, THE SYSTEM WILL ACCELERATE NORTHEASTWARD EAST OF HONSHU AND IS EXPECTED TO COMPLETE ETT BY TAU 72 AS THE SYSTEM BECOMES EMBEDDED IN THE MIDLATITUDE WESTERLIES AND GAINS STRONG 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 FAIR AGREEMENT, THEREFORE, THERE IS NOW MODERATE CONFIDENCE IN THE JTWC TRACK FORECAST.// NNNN NNNN