MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 28W (TRAMI) WARNING NR 13// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON 28W (TRAMI), LOCATED APPROXIMATELY 563 NM SOUTH-SOUTHEAST OF KADENA AB, HAS TRACKED WEST-NORTHWESTWARD AT 12 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS WARMING CLOUD TOPS AND A SMALL 7NM ROUND EYE, WHICH SUPPORTS THE CURRENT POSITION WITH HIGH CONFIDENCE. AN EYEWALL REPLACEMENT CYCLE WAS ONGOING IN A 231204Z MHS 89GHZ IMAGE, WHICH SHOWED DOUBLE EYEWALLS SURROUNDED BY A MOAT. A MORE RECENT 231650Z AMSR-2 89GHZ IMAGE SHOWS THE PRIMARY EYEWALL HAS ERODED AS THE SECONDARY EYEWALL BEGINS TO PREDOMINATE. THE INITIAL INTENSITY OF 28W IS ESTIMATED AT 120 KTS, BETWEEN ALL AGENCY DVORAK CURRENT INTENSITY ESTIMATES OF T6.0 (115 KTS) AND A 231711Z SATCON ESTIMATE OF 127 KTS. THE EYEWALL REPLACEMENT CYCLE HAS TEMPERED THE RECENT RAPID INTENSIFICATION TREND AS THE SECONDARY EYEWALL STARVES THE PRIMARY EYEWALL OF INFLOW, AND THE LATEST INTENSITY ESTIMATE REFLECTS ONLY 5 KTS OF INTENSIFICATION IN THE LAST 6 HOURS. UPPER-LEVEL ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH NEAR-RADIAL OUTFLOW, ENHANCED BY A TUTT CELL TO THE NORTHEAST AND A MIDLATITUDE TROUGH TO THE NORTH, AND LOW VERTICAL WIND SHEAR. SEA SURFACE TEMPERATURES ARE FAVORABLE AT 29C. TY 28W IS TRACKING WESTWARD ALONG THE SOUTHERN PERIPHERY OF A DEEP- LAYERED SUBTROPICAL RIDGE (STR) ENTRENCHED TO THE NORTH. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY TRAMI IS FORECAST TO TRACK WEST-NORTHWESTWARD UNDER THE STEERING INFLUENCE OF THE AFOREMENTIONED STR THROUGH TAU 24. AFTER TAU 24, A MIDLATITUDE SHORTWAVE TROUGH WILL MOVE INTO THE EAST CHINA SEA (ECS) AND JAPAN REGION, ERODING THE STR. AS THE TROUGH PASSES AND ERODES THE STR, THE FORWARD MOTION OF 28W WILL SLOW DRAMATICALLY AND IT WILL TURN POLEWARD. THE MAJORITY OF MODELS AND THE MULTI- MODEL CONSENSUS SHOW A SMALL KINK IN THE TRACK TO THE NORTH. GFS, HWRF, AND THE MOST RECENT RUN OF ECMWF ARE THE OUTLIERS AND SHOW A MORE DRAMATIC TURN TO THE NORTH, WITH ECMWF STARTING THE NORTHWARD TURN AT TAU 36. THIS IS A SHIFT IN PREDICTED TRACK FOR ECMWF, WHICH LAST RUN SHOWED A LESS DRASTIC TURN TO THE NORTH AND WAS MORE IN LINE WITH THE MULTI-MODEL CONSENSUS. TRACK SPEEDS ARE EXPECTED TO REMAIN SLOW THROUGH TAU 72 AS THE STR SLOWLY REBUILDS TO THE NORTH AND THE SYSTEM RETURNS TO A WEST-NORTHWESTWARD COURSE. THERE IS A 155 NM SPREAD IN MODELS AT TAU 72, AND GIVEN THE RECENT SHIFT IN ECMWF MODEL TRACK, CONFIDENCE IN THIS PORTION OF THE JTWC FORECAST TRACK IS LOW. RAPID INTENSIFICATION IS INDICATED IN NUMERICAL MODEL GUIDANCE THROUGH TAU 24. AFTER THE EYEWALL REPLACEMENT CYCLE CONCLUDES AND THE SECONDARY EYEWALL CONTRACTS, THE SYSTEM IS EXPECTED TO INTENSIFY TO SUPER TYPHOON STRENGTH BY TAU 12 UNDER VERY FAVORABLE CONDITIONS, WITH A PEAK INTENSITY OF 145 KNOTS ANTICIPATED BY TAU 24. GRADUAL WEAKENING WILL START AFTER TAU 48 AS ENVIRONMENTAL CONDITIONS DEGRADE. C. THROUGH TAU 120, TY 28W WILL MOVE NORTHWESTWARD UNDER THE REBUILT STR. TOWARDS THE END OF THE FORECAST PERIOD, A MIDLATITUDE SHORTWAVE TROUGH WILL APPROACH THE ECS. THE NORTHERN OUTLIERS OF GFS, HWRF, AND ECMWF THEN SHOW A MORE NORTH-NORTHWESTWARD TRACK IN RESPONSE TO THIS TROUGH ERODING THE STR. THE JTWC OFFICIAL FORECAST HAS BEEN SHIFTED SLIGHTLY TO THE NORTHEAST TO REFLECT THE SHIFTING ECMWF GUIDANCE, BUT STILL IS PLACED CLOSE TO THE MULTI-MODEL CONSENSUS WITH A TRACK TOWARD ISHIGAKI-JIMA. THERE IS LOW CONFIDENCE IN THIS PORTION OF THE JTWC TRACK FORECAST DUE TO THE 382 NM SPREAD IN MODEL GUIDANCE AT TAU 120. THE GRADUAL WEAKENING TREND IS FORECAST TO CONTINUE THROUGH TAU 120.// NNNN NNNN