MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 11W (KROSA) WARNING NR 011// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 11W (KROSA), LOCATED APPROXIMATELY 167 NM SOUTH- SOUTHWEST OF IWO TO, JAPAN, HAS TRACKED NORTHEASTWARD AT 01 KNOT OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS THE SYSTEM HAS BECOME QUASI-STATIONARY (QS) AS IT RAPIDLY INTENSIFIED (RI) AND MAINTAINED A 14-NM EYE. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE EYE FEATURE. THE INITIAL INTENSITY OF 100KTS IS BASED ON THE DVORAK ESTIMATES OF T5.5/102KTS FROM PGTW AND RJTD AND REFLECT THE RI. ENVIRONMENTAL ANALYSIS INDICATES EXCELLENT EQUATORWARD AND EASTWARD OUTFLOW (TEMPERED ONLY BY SUBSIDENCE ALONG THE NORTHWEST SECTOR), LOW VERTICAL WIND SHEAR (VWS) AND WARM SST (30C). TY 11W IS IN A COL BETWEEN A WEAKENED SUBTROPICAL RIDGE (STR) TO THE EAST AND A BUILDING NEAR EQUATORIAL RIDGE (NER) TO THE SOUTH. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY 11W WILL REMAIN QS IN THE COL UP TO TAU 12. AFTERWARD, THE NER WILL SLOWLY STEER IT NORTHEASTWARD. AROUND TAU 36, THE STR WILL REBUILD AND RESUME STEERING AND DRIVE THE SYSTEM NORTH-NORTHWESTWARD TOWARD JAPAN. INCREASING VWS AND REDUCED POLEWARD OUTFLOW WILL GRADUALLY WEAKEN THE SYSTEM DOWN TO 70KTS BY TAU 72. THE NUMERICAL MODELS ARE IN OVERALL GOOD AGREEMENT; HOWEVER, GIVEN THE UNCERTAINTY IN THE TRANSITION BETWEEN THE STEERING MECHANISMS, THERE IS LOW CONFIDENCE IN THIS PORTION OF THE JTWC FORECAST TRACK. C. AFTER TAU 72, TY KROSA WILL CONTINUE TRACKING NORTH-NORTHWESTWARD UNDER THE INFLUENCE OF THE STR. COOLING SSTS, IN ADDITION TO THE INCREASING VWS, WILL CONTINUE TO ERODE THE SYSTEM DOWN TO 65KTS BY TAU 120. THE NUMERICAL MODELS SPREAD OUT TO OVER 400 NM BY TAU 120, LENDING TO LOW CONFIDENCE IN THE EXTENDED PORTION OF THE JTWC FORECAST TRACK.// NNNN NNNN