MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (BAVI) WARNING NR 012// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 09W (BAVI), LOCATED APPROXIMATELY 450 NM SOUTH- SOUTHWEST OF CHINHAE, SOUTH KOREA, HAS TRACKED NORTHEASTWARD AT 07 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A COMPACT SYSTEM WITH DENSE, SUSTAINED CONVECTION WRAPPING AROUND AN IRREGULAR EYE 27 NM IN DIAMETER. THE CURRENT POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE EYE FEATURE PRESENT IN THE MSI AND COMPOSITE RADAR LOOPS. THE CURRENT INTENSITY IS PLACED WITH FAIR CONFIDENCE BETWEEN MULTIAGENCY DVORAK CURRENT INTENSITY ESTIMATES OF T4.0 (65 KTS, RJTD AND RCTP) AND T4.5 (77 KTS, PGTW). THE STRONG CONVECTIVE SIGNATURE AND EYE DEVELOPMENT IN THE MSI LOOP SUPPORT AN INTENSITY CLOSER TO THE HIGHER END OF SUBJECTIVE DVORAK VALUES. TY 09W HAS CONTINUED TO TRACK ALONG THE WESTERN PERIPHERY OF A BUILDING SUBTROPICAL RIDGE POSITIONED TO THE EAST, AND HAS CONTINUED TO INTENSIFY OVER THE PAST SIX HOURS DUE TO THE CONTINUED FAVORABLE ENVIRONMENT OF LOW (10-15 KNOTS) VERTICAL WIND SHEAR (VWS), VERY WARM (29-30C) SEA SURFACE TEMPERATURES (SSTS) AND ESTABLISHED EQUATORWARD OUTFLOW ALOFT. 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY 09W WILL CONTINUE TO TRACK POLEWARD OVER THE NEXT 72 HOURS ALONG THE WESTERN PERIPHERY OF THE BUILDING SUBTROPICAL RIDGE TO THE EAST. RAPID INTENSIFICATION IS ANTICIPATED THROUGH TAU 36 DUE TO WARM SSTS (30 CELSIUS) AND LOW VWS (10-15 KTS), COUPLED WITH THE WELL ESTABLISHED EQUATORWARD OUTFLOW ALOFT WHICH WILL STRENGTHEN THE SYSTEM TO 105 KTS BY TAU 24 AND A PEAK INTENSITY OF 110 KTS BY TAU 36. AFTER THIS TIME, INCREASING VWS WILL CAUSE THE SYSTEM TO WEAKEN SLIGHTLY BY TAU 48 TO AN INTENSITY OF 105 KTS. THEREAFTER, THE SYSTEM WILL CONTINUE TO TRACK POLEWARD AS IT BEGINS TO INTERACT WITH THE BAROCLINIC ZONE OVER THE YELLOW SEA. TY BAVI WILL MAKE LAND FALL OVER THE KOREAN PENINSULA AT THIS TIME AND BEGIN EXTRATROPICAL TRANSITION AT TAU 72. NUMERICAL MODEL TRACK SOLUTIONS ARE IN TIGHT AGREEMENT WITH A CROSS TRACK SPREAD OF 100 NM AT TAU 48 INCREASING SLIGHTLY TO 130 NM BY TAU 72. MODEL SOLUTIONS HAVE OSCILLATED ABOUT THE JTWC MULTI-MODEL CONSENSUS WITH GFS, NAVGEM AND UK MODELS TO THE WEST AND JGSM AND ECMWF MODELS TO THE EAST. NONE OF THE AVAILABLE MODEL FORECASTS INDICATE STORM CENTER PASSAGE OVER SOUTH KOREA, BUT THE EASTERN GROUP DOES CARRY THE STORM CENTER ALONG THE WESTERN SHORE. THE JTWC MULTI-MODEL CONSENSUS HAS BEEN VERY CONSISTENT FOR MULTIPLE MODEL RUNS. THE INITIAL PORTION OF THE JTWC FORECAST TRACK IS THEREFORE PLACED WITH HIGH CONFIDENCE AS IT IS SITUATED NEAR THE CONSENSUS AND NEAR PREVIOUS JTWC FORECAST TRACKS. C. AS THE SYSTEM TRACKS OVER MAINLAND CHINA, IT WILL ACCELERATE POLEWARD IT BECOMES FULLY EMBEDDED IN THE BAROCLINIC ZONE. RAPID WEAKENING IS ANTICIPATED DUE TO UNFAVORABLE UPPER-LEVEL CONDITIONS AND THE FRICTIONAL EFFECTS OF LAND. THE SYSTEM WILL COMPLETE EXTRATROPICAL TRANSITION BY TAU 96 AS IT BECOMES EMBEDDED IN THE DEEP WESTERLY FLOW ALOFT. NUMERICAL MODEL SOLUTIONS DIVERGE GREATLY AFTER TAU 72, WITH A TOTAL SPREAD OF 365 NM BY TAU 120. DESPITE THIS HIGH DEGREE OF SPREAD IN THE FINAL PORTION OF THE FORECAST TRACK, THERE STILL REMAINS HIGH CONFIDENCE IN THE OVERALL JTWC FORECAST TRACK DUE TO THE TIGHT PACKING OF MODEL SOLUTIONS OVERALL. NNNN NNNN