MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 15W (LINGLING) WARNING NR 13// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 15W (LINGLING), LOCATED APPROXIMATELY 194 NM SOUTHWEST OF KADENA AB, OKINAWA, JAPAN, HAS TRACKED NORTHWARD AT 06 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS TIGHTLY-CURVED BANDS WRAPPED TIGHTER INTO THE WELL-DEFINED 15NM EYE. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE EYE FEATURE OBSERVED IN A 042227Z SSMIS 37 GHZ MICROWAVE IMAGE WHICH IS CONSISTENT WITH THE CIRCULATION DEPICTED IN A COMPOSITE RADAR LOOP FROM JMA AND A SURFACE OBSERVATION AT MIYAKOJIMA (47927), LOCATED 40NM TO THE NORTH. THE INITIAL INTENSITY OF 115 KTS IS BASED ON DVORAK INTENSITY ESTIMATES OF T6.0/115 KTS FROM PGTW AND RCTP. UPPER-LEVEL ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH LOW TO MODERATE (15-20KT) VERTICAL WIND SHEAR (VWS) OFFSET BY VIGOROUS EQUATORWARD OUTFLOW. ADDITIONALLY, THE SOUTHERLY UPPER-LEVEL WINDS ARE IN PHASE WITH THE NORTHWARD MOTION OF THE SYSTEM, DECREASING THE EFFECT OF VWS ON THE SYSTEM. SEA SURFACE TEMPERATURES (SSTS) AT 28-29C REMAIN CONDUCIVE. TY 15W MAINTAINS A NORTHWARD TRACK UNDER THE STEERING INFLUENCE OF THE SUBTROPICAL RIDGE (STR) TO THE EAST. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY 15W WILL CONTINUE NORTHWARD UNDER THE STR. AFTER TAU 48, IT WILL TRACK MORE NORTH-NORTHEASTWARD IN THE YELLOW SEA AS THE STR RECEDES EASTWARD IN RESPONSE TO A MIDLATITUDE TROUGH APPROACHING FROM THE NORTHWEST. THE OVERALL FAVORABLE ENVIRONMENT WILL PROMOTE A PERIOD OF CONTINUED INTENSIFICATION TO A PEAK OF 120 KTS AT TAUS 12-24. AS THE SYSTEM ENTERS THE YELLOW SEA, INCREASING VWS AND COOLING SSTS WILL BEGIN TO WEAKEN THE SYSTEM. IN THIS PORTION OF THE JTWC TRACK, NUMERICAL MODELS ARE IN TIGHT AGREEMENT LENDING HIGH CONFIDENCE. C. AFTER TAU 72, TY 15W IS EXPECTED TO MAKE LANDFALL AND INTERACT WITH THE RUGGED TERRAIN OF CENTRAL NORTH KOREA. BY TAU 96, IT WILL COMMENCE EXTRA-TROPICAL TRANSITION (ETT) AND ACCELERATE NORTHEASTWARD. BY TAU 120, TY 15W WILL COMPLETE ETT AND CONTINUE TO RAPIDLY WEAKEN AS THE SYSTEM ENCOUNTERS INCREASING VWS AND RUGGED TERRAIN. NUMERICAL MODELS REMAIN IN GOOD AGREEMENT WITH GFS AS THE NOTABLE RIGHT-OF-TRACK OUTLIER. DUE TO UNCERTAINTY IN TRACK SPEEDS OVER RUGGED TERRAIN, THERE IS MODERATE CONFIDENCE IN THIS EXTENDED PORTION OF THE JTWC FORECAST THAT IS LAID JUST LEFT OF MODEL CONSENSUS TO OFFSET THE UNLIKELY GFS TRACK INTO THE STR.// NNNN NNNN