MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 26W (MANGKHUT) WARNING NR 25// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUPER TYPHOON (STY) 26W (MANGKHUT), LOCATED APPROXIMATELY 592 NM EAST OF MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 13 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A 185NM DIAMETER CONVECTIVE CORE WITH A 25NM ROUND EYE AND BANDING FEATURE. DUE TO THE LACK OF HIGH RESOLUTION MICROWAVE IMAGERY, IT IS DIFFICULT TO DETERMINE IF THE EYEWALL REPLACEMENT CYCLE (ERC) HAS COMPLETED. HOWEVER, STY 26W HAS WEAKENED SLIGHTLY WITH WARMING CLOUD TOPS AND IS NOW ASSESSED AT 145 KNOTS BASED ON DVORAK CURRENT INTENSITY ESTIMATES RANGING FROM 7.0 (140 KNOTS) TO 7.5 (155 KNOTS). UPPER-LEVEL ANALYSIS CONTINUES TO INDICATE A VERY FAVORABLE ENVIRONMENT WITH RADIAL OUTFLOW, ENHANCED BY A TUTT CELL TO THE EAST, AND LOW VERTICAL WIND SHEAR. ADDITIONALLY, WARM SST (29- 30C) AND HIGH OCEAN HEAT CONTENT VALUES ARE VERY FAVORABLE. STY 26W IS TRACKING WESTWARD UNDER THE STEERING INFLUENCE 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. STY 26W WILL TRACK WEST-NORTHWESTWARD THROUGH THE FORECAST PERIOD WITH LANDFALL ALONG THE NORTHEAST COAST OF LUZON BY TAU 42. STY 26W WILL MAINTAIN STY INTENSITY THROUGH TAU 36 UNDER VERY FAVORABLE ENVIRONMENTAL CONDITIONS. AFTER TAU 36, STY 26W WILL WEAKEN SIGNIFICANTLY AS IT TRACKS OVER THE MOUNTAINOUS REGION OF LUZON, RE-EMERGING OVER THE SOUTH CHINA SEA (SCS) NEAR TAU 54 NEAR 110 KNOTS. C. AFTER TAU 72, STY MANGKHUT WILL CONTINUE ON A WEST- NORTHWESTWARD TRAJECTORY UNDER THE STEERING INFLUENCE OF THE STR. THE SYSTEM WILL TRACK ACROSS THE SCS JUST SOUTH OF HONG KONG MAKING LANDFALL OVER SOUTHERN CHINA NEAR TAU 96. THE SYSTEM WILL WEAKEN BY TAU 96 DUE TO INTERACTION WITH LAND WITH MORE RAPID WEAKENING AS IT TRACKS INTO NORTHERN VIETNAM BY TAU 120. THE DYNAMIC MODEL GUIDANCE AND ENSEMBLE MODEL GUIDANCE REMAINS IN EXCEPTIONALLY TIGHT AGREEMENT LENDING HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.// NNNN NNNN