WDPN32 PGTW 270300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 18W (NORU) WARNING NR 021// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 15.5N 112.2E INITIAL INTENSITY: 125 KTS GEOGRAPHIC REFERENCE: 513 NM WEST OF MANILA, PHILIPPINES MOVEMENT PAST 6 HOURS: WESTWARD AT 17 KTS SIGNIFICANT WAVE HEIGHT: 50 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A SYSTEM THAT CONTINUES TO RAPIDLY INTENSIFY, WITH DEEP CONVECTIVE FEEDER BANDS ON THE EASTERN PERIPHERY WRAPPING AROUND AN EYE FEATURE THAT IS PARTLY CLOUD-FILLED. AN EARLIER 261652Z GMI 89 GHZ MICROWAVE IMAGE DEPICTS A 40 NM DEEP CONVECTIVE CURVED BAND FULLY SURROUNDING A 5NM MICROWAVE EYE, INDICATING THE SYSTEM HAS CONTINUED TO RAPIDLY INTENSIFY OVER THE PAST 6 HOURS. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE CLOUD-FILLED EYE FEATURE IN ANIMATED VISIBLE IMAGERY ALONG WITH THE EXTRAPOLATED GMI MICROWAVE IMAGE. THE INITIAL INTENSITY IS ALSO PLACED WITH MEDIUM CONFIDENCE BASED ON SUBJECTIVE DVORAK INTENSITIES FROM PGTW T6.5, RJTD T5.5, AND KNES T6.0. OBJECTIVE AUTOMATED DVORAK ESTIMATES INTENSITIES SEEM TO BE UNDER ESTIMATING THE MAXIMUM INTENSITY AND THEREFORE THE INITIAL INTENSITY IS PLACED CLOSER TO SUBJECTIVE AGENCY DVORAK ESTIMATES. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE TO THE NORTH DEEP-LAYER SUBTROPICAL RIDGE TO THE NORTH AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T6.5 - 127 KTS RJTD: T5.5 - 102 KTS KNES: T6.0 - 115 KTS CIMSS ADT: 90 KTS AT 262340Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 10-15 KTS SST: 29-30 CELSIUS OUTFLOW: STRONG RADIAL ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: LOW 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TY 18W (NORU) CONTINUES TO RAPIDLY INTENSIFY OVER THE PAST 12 HOURS AS ENVIRONMENTAL CONDITIONS ARE FAVORABLE WITH MODERATE VERTICAL WIND SHEAR (VWS) (10-15KTS), OFFSET BY WARM SEA SURFACE TEMPERATURES (29-30C), AND STRONG RADIAL OUTFLOW. TY 18W IS FORECAST TO TRACK WESTWARD THROUGH THE FORECAST PERIOD UNDER THE STEERING INFLUENCE OF THE STR POSITIONED TO THE NORTH, BEFORE MAKING LANDFALL INTO CENTRAL VIETNAM WITHIN THE NEXT 24 HOURS. DUE TO THE CURRENT FAVORABLE ENVIRONMENTAL CONDITIONS THE SYSTEM HAS LIKELY REACHED ITS PEAK INTENSITY OF 125 KTS, HOWEVER AS THE SYSTEM CONTINUES TO TRACK WESTWARD OVER THE NEXT 12-24 HOURS, TY 18W WILL BEGIN TO BE INFLUENCED BY INCREASING VWS AND LAND INTERACTION, WHICH WILL RESULT IN THE SYSTEM GRADUALLY DECREASING IN INTENSITY. AFTER TAU 24, TY 18W WILL MAKE LANDFALL INTO CENTRAL VIETNAM, AS LAND INTERACTION AS WELL AS AN INCREASE IN VWS WILL DECREASE THE SYSTEMS INTENSITY EVEN FURTHER. BY TAU 48, THE SYSTEM TRACKS FURTHER INLAND OVER SOUTHEAST ASIA WITH DISSIPATION EXPECTED. MODEL DISCUSSION: NUMERICAL MODELS ARE IN VERY GOOD AGREEMENT REGARDING THE TRACK FORECAST, WITH THE EXCEPTION OF THE NAVGEM TRACKER. THIS LENDS HIGH CONFIDENCE IN THE JTWC TRACK FORECAST THROUGH OUT THE FORECAST. THE OVERALL CONFIDENCE IN THE JTWC INTENSITY FORECAST IS MEDIUM DUE TO SOME UNCERTAINTY IN THE MODEL GUIDANCE INTENSITY OVER THE NEXT 24 HOURS, AS GFS DECAY SHIPS (DSHA) SHOWS A MORE GRADUAL DECREASE IN INTENSITY FROM THE OTHER MODEL GUIDANCE. HOWEVER, AFTER LANDFALL, THE BULK OF THE INTENSITY GUIDANCE IS IN OVERALL GOOD AGREEMENT OF A RAPID DECREASE THROUGH TAU 48. FORECAST CONFIDENCE: TRACK 0 - 72 HR: HIGH INTENSITY 0 - 72 HR: MEDIUM// NNNN