MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 28W (TRAMI) WARNING NR 27// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 28W (TRAMI), LOCATED APPROXIMATELY 298 NM SOUTH-SOUTHEAST OF KADENA AB, OKINAWA, JAPAN, HAS TRACKED NORTHEASTWARD AT 01 KNOT OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS TY 28W HAS MAINTAINED A WIDE AND RAGGED EYE WITH MODERATE TO DEEP CONVECTION WRAPPING AROUND IT. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE AND IS BASED ON A 270600Z HIMAWARI VISIBLE SATELLITE IMAGE SHOWING THE LARGE EYE. THE INITIAL INTENSITY OF 90 KNOTS IS BASED ON A DVORAK CURRENT INTENSITY (CI) ESTIMATE OF T5.0 (90 KNOTS) FROM PGTW AND HEDGED SLIGHTLY ABOVE A 270506Z SATCON ESTIMATE OF 87 KNOTS. ENVIRONMENTAL ANALYSIS SHOWS THAT TY 28W IS EXPERIENCING FAVORABLE VERTICAL WIND SHEAR (5 TO 10 KNOTS) AND HAS EXCELLENT RADIAL OUTFLOW. SEA SURFACE TEMPERATURES REMAIN FAVORABLE, BETWEEN 28 AND 29 DEGREES CELSIUS. HOWEVER, OCEAN HEAT CONTENT HAS DIMINISHED DUE TO THE FACT THAT TY 28W HAS REMAINED QUASI-STATIONARY OVER THE PAST 24 HOURS AND HAS CAUSED UPWELLING IN THE AREA. TY 28W REMAINS IN A WEAK STEERING ENVIRONMENT WHILE IN BETWEEN A SUBTROPICAL RIDGE (STR) LOCATED TO THE WEST AND A SECOND STR LOCATED TO THE EAST. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY 28W IS FORECAST TO TRACK SLOWLY NORTH TO NORTHWESTWARD WHILE IT REMAINS POSITIONED BETWEEN THE TWO AFOREMENTIONED STRS. THE STR TO THE EAST WILL EVENTUALLY BECOME THE DOMINANT STEERING FEATURE AND ALLOW FOR TY 28W TO INCREASE IN TRACK SPEED AS IT MOVES TO THE NORTHWEST. BY TAU 36, TY 28W WILL BEGIN TO ROUND THE STR AXIS AND THEN START TO TRACK NORTHEASTWARD. AS TY 28W ROUNDS THE STR IT WILL ENCOUNTER WARMER SEA SURFACE TEMPERATURES AND OUTFLOW WILL IMPROVE AS IT TAPS INTO THE WESTERLIES. THIS WILL ALLOW TY 28W TO RE-INTENSIFY TO 105 KNOTS BY TAU 48. THE JTWC FORECAST TRACK IS PLACED NEAR THE MULTI-MODEL CONSENSUS. MODELS AGREE THAT TY 28W WILL TRACK NORTHWESTWARD AND THEN NORTHEASTWARD. HOWEVER, DYNAMIC MODEL GUIDANCE HAS A SPREAD OF 120 NM BY TAU 48 WITH NAVGEM THE WESTERN MOST OUTLIER AND CTCX THE EASTERN MOST OUTLIER. THEREFORE, THERE IS LOW CONFIDENCE IN THIS PORTION OF THE JTWC FORECAST TRACK. C. AFTER TAU 72, TY 28W WILL CONTINUE TO ACCELERATE TO THE NORTHEAST AROUND THE STR AS IT INTERACTS WITH THE APPROACHING WEST TO EAST MOVING SHORTWAVE THOUGH. TY 28W WILL BEGIN EXTRA-TROPICAL TRANSITION (ETT) BY TAU 72 AS IT INTERACTS WITH THE TROUGH. AS TY 28W ACCELERATES NORTHEASTWARD IT WILL DECREASE IN OVERALL INTENSITY WITH AN EXPANDING WIND FIELD. TY 28W WILL COMPLETE ETT BY TAU 96. DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT THAT TY 28W WILL TRACK NORTHEASTWARD BUT THERE IS A WIDE RANGE IN TRACK SPEED. THEREFORE, THERE IS LOW CONFIDENCE IN THIS PORTION OF THE JTWC FORECAST TRACK.// NNNN NNNN