MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 16W (MERANTI) WARNING NR 15// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUPER TYPHOON 16W (MERANTI), LOCATED APPROXIMATELY 493 NM SOUTH OF KADENA AB, HAS TRACKED WEST-NORTHWESTWARD AT 11 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY AND A 120551Z MHS 89GHZ MICROWAVE IMAGE DEPICT AN INTENSE SUPER TYPHOON WITH DEEP CONVECTION, MULTIPLE SPIRAL BANDS, AND A SMALL EYE LESS THAN 10NM IN DIAMETER. THERE IS EXCELLENT CONFIDENCE IN THE CURRENT POSITION AND RECENT TRACK MOTION. UPPER-LEVEL ANALYSIS INDICATES AN ENVIRONMENT OF LOW VERTICAL WIND SHEAR AND EXCELLENT RADIAL OUTFLOW. TOGETHER WITH AMPLE WARM OCEAN WATER, STY 16W HAS UNDERGONE RAPID INTENSIFICATION. THE CURRENT INTENSITY OF 130 KNOTS IS BASED ON DVORAK INTENSITY ESTIMATES OF T6.5 FROM ALL AGENCIES. STY 16W CONTINUES TO TRACK TOWARD THE WEST-NORTHWEST UNDER THE STEERING INFLUENCE OF A SUBTROPICAL RIDGE (STR) TO THE NORTH. 3. FORECAST REASONING. A. NO CHANGE IN THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. THROUGH TAU 72, STY 16W WILL TRACK GENERALLY WEST- NORTHWESTWARD UNDER THE STEERING INFLUENCE OF THE DEEP-LAYERED SUBTROPICAL RIDGE (STR). THE MAJORITY OF DYNAMIC MODEL GUIDANCE SUGGEST A MORE WESTWARD TRACK THROUGH THE LUZON STRAIT. HOWEVER, THE OFFICIAL JTWC FORECAST LIES ON THE POLEWARD SIDE OF THE ENVELOPE OF TRACK GUIDANCE GIVEN THE RECENT MOTION BEING MORE TOWARD THE NORTHWEST. FURTHER INTENSIFICATION IS POSSIBLE, AND STY 16W IS EXPECTED TO REACH A PEAK INTENSITY OF 140 KNOTS FROM TAU 12 TO 24, FOLLOWED BY SOME FLUCTUATIONS IN INTENSITY AND SOME WEAKENING AS THE CIRCULATION INTERACTS WITH THE TOPOGRAPHY OF SOUTHERN TAIWAN. MORE SIGNIFICANT CHANGES TO THE TRACK FORECAST MAY BE NECESSARY WITH FUTURE ADJUSTMENTS TO THE TRACK FORECAST. C. AFTER TAU 72, THE MAJORITY OF DYNAMIC MODEL GUIDANCE TAKES STY 16W THROUGH THE LUZON STRAIT AND TAIWAN STRAIT TOWARD A SECOND LANDFALL IN MAINLAND CHINA, UNDER THE STEERING INFLUENCE OF THE STR AXIS TO THE NORTH. AFTER LANDFALL, THERE ARE DIFFERENCES IN TIMING OF A POTENTIAL TURN TOWARD THE NORTH, WITH SOME MODELS CONTINUING TO SUGGEST A MORE WESTWARD MOTION. REGARDLESS, THE CIRCULATION OF STY 16W SHOULD WEAKEN QUICKLY, PARTICULARLY IF IT EXPERIENCES SIGNIFICANT STRUCTURAL DISRUPTIONS FROM THE CENTRAL MOUNTAIN RANGE OF TAIWAN. DISSIPATION IS EXPECTED TO OCCUR AROUND TAU 96. DUE TO THE LARGE MODEL SPREAD BEYOND 48 HOURS, THERE IS LOW CONFIDENCE IN THE JTWC TRACK FORECAST BEYOND THAT TIME.// NNNN NNNN