MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 16W (MERANTI) WARNING NR 17// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUPER TYPHOON (STY) 16W (MERANTI), LOCATED APPROXIMATELY 436 NM SOUTH OF KADENA AB, OKINAWA, JAPAN HAS TRACKED WEST-NORTHWESTWARD AT 15 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS AN IMPRESSIVE CYCLONE WITH A DEEP CONVECTIVE CORE SURROUNDING A SHARP 8NM EYE WHICH SUPPORTS THE CURRENT POSITION WITH HIGH CONFIDENCE. THE CLOUD TOPS HAVE WARMED SLIGHTLY OVER THE PAST FEW HOURS AS THE SYSTEM RESPONDS TO DIURNAL PHASES. A 121826Z AMSU MICROWAVE IMAGE SHOWS MULTIPLE CONVECTIVE BANDS WRAPPING INTO THE WELL-DEFINED EYE. STY 16W REMAINS AT 155 KNOTS BASED ON DVORAK CURRENT INTENSITY ESTIMATES OF T7.5 (155 KNOTS) FROM PGTW AND RJTD. THE WATER VAPOR LOOP SHOWS RADIAL OUTFLOW DUE TO A POINT SOURCE ANTI-CYCLONE OVER THE TOP OF THE SYSTEM WITH LOW (5-10 KNOT) VERTICAL WIND SHEAR (VWS). SEA SURFACE TEMPERATURES NEAR 30 CELSIUS AND HIGH OCEAN HEAT CONTENT ARE ALSO FAVORABLE FOR FURTHER INTENSIFICATION. 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; HOWEVER, THE FORECAST TRACK HAS SHIFTED SOUTHWARD INTO THE TAIWAN STRAIT. B. THROUGH TAU 72, STY 16W WILL TRACK GENERALLY WEST- NORTHWESTWARD UNDER THE STEERING INFLUENCE OF THE STR. VERY FAVORABLE ENVIRONMENTAL CONDITIONS WILL SUPPORT THE POTENTIAL FOR ADDITIONAL INTENSIFICATION OVER THE NEXT 12 TO 24 HOURS. AFTERWARDS, LAND INTERACTION WITH TAIWAN AND INCREASING VWS WILL BEGIN THE WEAKENING PHASE. STY MERANTI WILL MAKE LANDFALL ALONG THE COAST OF CHINA JUST AFTER TAU 48 AS A STRONG TYPHOON. DYNAMIC MODEL GUIDANCE SHOWS TWO POSSIBLE SCENARIOS FOR THE SYSTEM BUT OVERALL CONTINUE TO WALK THE TRACK SOUTHWARD INTO THE TAIWAN STRAIT. THE FIRST SCENARIO SHOWS LANDFALL OVER THE SOUTHERN TIP OF TAIWAN WITH THE SECOND SCENARIO IS SHOWING A TRACK OVER THE TAIWAN STRAIT. C. IN THE EXTENDED FORECAST, STY 16W WILL CONTINUE TRACKING OVER LAND AND FULLY DISSIPATE DUE TO LAND INTERACTION AND INCREASED VWS DUE TO INTERACTION WITH THE ZONAL MID-LATITUDE WESTERLIES. MODEL GUIDANCE IN THE EXTENDED FORECAST DIVERGES GREATLY DUE TO THE RAPID WEAKENING OF THE CYCLONE. VWS IS EXPECTED TO BE IN EXCESS OF 30 KNOTS AT THIS TIME. THE CURRENT FORECAST HAS BEEN SHIFTED FURTHER SOUTH, WITH LOW CONFIDENCE, CLOSE TO THE MULTI-MODEL CONSENSUS.// NNNN NNNN