MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 15W (LINGLING) WARNING NR 10// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 15W (LINGLING), LOCATED APPROXIMATELY 282 NM SOUTH- SOUTHWEST OF KADENA AB, OKINAWA, HAS TRACKED EAST-NORTHEASTWARD AT 06 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS TIGHTLY-CURVED BANDING WRAPPING INTO A RAGGED 11NM EYE. A 040517Z AMSR2 36GHZ IMAGE DEPICTS A WELL-DEFINED MICROWAVE EYE FEATURE, WHICH SUPPORTS THE INITIAL POSITION WITH GOOD CONFIDENCE. THE INITIAL INTENSITY REMAINS ASSESSED AT 75 KNOTS BASED ON DVORAK INTENSITY ESTIMATES OF T4.5 (77 KNOTS). UPPER-LEVEL ANALYSIS INDICATES A GENERALLY FAVORABLE ENVIRONMENT WITH LOW TO MODERATE (15-20 KNOTS) VERTICAL WIND SHEAR (VWS) OFFSET BY VIGOROUS EQUATORWARD OUTFLOW. POLEWARD OUTFLOW HAS IMPROVED SLIGHTLY BUT REMAINS WEAK DUE TO THE PRESENCE OF SUBTROPICAL WESTERLIES TO THE NORTH. SEA SURFACE TEMPERATURES (28-29C) REMAIN CONDUCIVE. TY 15W IS TRACKING SLOWLY EAST-NORTHEASTWARD ALONG A WEAK EXTENSION OF THE SUBTROPICAL RIDGE (STR) TO THE SOUTHEAST. HOWEVER, THE 04/00Z UPPER AIR SOUNDINGS FROM MINAMIDAITO-JIMA AND NAZE INDICATE SOUTHEASTERLY TO EAST-SOUTHEASTERLY FLOW FROM THE SURFACE TO 350MB, WHICH PROVIDES EVIDENCE OF THE STR SITUATED OVER THE RYUKYU ISLANDS. THIS DOMINANT STR WILL TURN THE SYSTEM NORTHWARD WITHIN THE NEXT 12 HOURS. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. THE 34-KNOT AND 50-KNOT WIND RADII ARE BASED ON A DETAILED ANALYSIS OF A RECENT ASCAT BULLSEYE. B. AS MENTIONED PREVIOUSLY, THE STR SITUATED OVER THE RYUKYU ISLANDS AND SOUTH OF JAPAN IS EXPECTED TO TURN THE SYSTEM NORTHWARD WITHIN THE NEXT 12 HOURS. HOWEVER, THERE IS SOME UNCERTAINTY IN THE EXACT TIMING OF THE POLEWARD SHIFT. DYNAMIC MODEL GUIDANCE IS IN TIGHT AGREEMENT THROUGH TAU 48 WITH A 40NM SPREAD IN SOLUTIONS AT TAU 48. THE MODELS DIVERGE SLIGHTLY BUT REMAIN IN GOOD AGREEMENT THROUGH TAU 72 SHOWING A NORTHWARD TRACK. ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE THROUGH TAU 36, THEREFORE, TY 15W IS EXPECTED TO INTENSIFY TO A PEAK OF 105 KNOTS. GRADUAL WEAKENING IS EXPECTED AFTER TAU 36. THE JTWC FORECAST TRACK IS PLACED NEAR THE MULTI-MODEL CONSENSUS WITH HIGH CONFIDENCE. C. IN THE LONG TERM, TY 15W WILL RECURVE NORTH-NORTHEASTWARD TO NORTHEASTWARD WHILE UNDERGOING EXTRA-TROPICAL TRANSITION (ETT). RAPID WEAKENING IS ANTICIPATED AS THE SYSTEM EXNCOUNTERS COOLER SST, INCREASING VWS AND TRACKS OVER LAND. THE SYSTEM WILL COMPLETE ETT BY TAU 120. THERE IS MODERATE CONFIDENCE IN THIS PORTION OF THE JTWC FORECAST TRACK DUE TO UNCERTAINTY IN TRACK SPEEDS.// NNNN NNNN