WDPN32 PGTW 241500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 18W (NORU) WARNING NR 011// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 15.6N 126.0E INITIAL INTENSITY: 75 KTS GEOGRAPHIC REFERENCE: 296 NM NORTHEAST OF MANILA, PHILIPPINES MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 09 KTS SIGNIFICANT WAVE HEIGHT: 24 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED SATELLITE IMAGERY (EIR) DEPICTS A SMALL ASYMMETRIC 6NM EYE FORMING AND CLOSING AROUND THE LOW-LEVEL CIRCULATION CENTER (LLCC), LENDING OVERALL HIGH CONFIDENCE IN THE INITIAL POSITION. THE INITIAL INTENSITY IS ASSESSED AT 75 KNOTS BASED ON MULTIPLE AGENCY DVORAK INTENSITY ESTIMATES AND THE ADVANCED DVORAK TECHNIQUE (ADT) SHOWN BELOW, LENDING OVERALL HIGH CONFIDENCE. ENVIRONMENTAL CONDITIONS ARE VERY FAVORABLE WITH MODERATE RADIAL OUTFLOW, ENHANCED BY AN UPPER-LOW OVER THE CONTINUES MIGRATING WEST OVER THE SOUTH CHINA SEA, AND LOW VERTICAL WIND SHEAR (VWS). INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF THE DEEP-LAYERED SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTH. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T4.5 - 77 KTS RJTD: T4.5 - 77 KTS KNES: T5.0 - 90 KTS CIMSS ADT: 74 KTS AT 241140Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE VWS: 0-5 KTS SST: 29-30 CELSIUS OUTFLOW: MODERATE RADIAL ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: HIGH 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 BEGAN SHOWING SIGNS OF RAPID INTENSIFICATION AS IT CONTINUES TRACKING WEST-SOUTHWEST TOWARDS LUZON. THE FAVORABLE CONDITIONS WITH THE IMPROVED OUTFLOW ARE ALLOWING FURTHER DEVELOPMENT TO A NEW PEAK INTENSITY OF 85 KNOTS BEFORE MAKING LANDFALL NEAR CAPE ENCANTO, PHILIPPINES. THE LAND INTERACTION WILL CAUSE A BRIEF DECREASE IN INTENSITY BEFORE THE SYSTEM REEMERGES OVER THE VERY WARM WATERS OF THE SOUTH CHINA SEA. BY TAU 48 THE SYSTEM WILL QUICKLY RE-INTENSIFY BACK TO TYPHOON STRENGTH ALONG ITS WESTWARD TRACK TOWARDS VIETNAM AND SOUTHEAST ASIA. BETWEEN TAUS 48 AND 72 THE ANOTHER OPPORTUNITY EXISTS FOR THE SYSTEM TO UNDERGO RAPID INTENSIFICATION (RI) WITH TY NORU. THE SYSTEM IS DUE TO MAKE ANOTHER PEAK INTENSITY OF 90 KNOTS JUST BEFORE MAKING SECONDARY LANDFALL, NEAR DA NANG, VIETNAM. RAPID WEAKENING WILL OCCUR ONCE THE SYSTEM TRACKS OVER SOUTHEAST ASIA. MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE REMAINS IN TIGHT AGREEMENT THROUGH THE FORECAST PERIOD WITH A MERE 50NM SPREAD OUT THROUGH 72 HOURS, LENDING HIGH CONFIDENCE TO THE JTWC FORECAST TRACK. AFTER THE SYSTEM MAKES SECONDARY LANDFALL THE MODEL TRACK GUIDANCE SPREADS GREATLY DUE TO THE LAND INTERACTION, LOWERING THE JTWC TRACK CONFIDENCE BEYOND TAU 72. THE INTENSITY GUIDANCE CAPTURED THE INITIAL RI, WITH COAMPS-TC AND HWRF MAXING OUT AT 100 KNOTS BEFORE THE SYSTEM MAKES INITIAL LANDFALL ON LUZON. AFTER THE INITIAL LANDFALL INTERACTION, THERE IS A SECONDARY RI POTENTIAL OVER THE SOUTH CHINA SEA WITH COAMPS-TC ONCE AGAIN MAXING OUT AT 110 KNOTS AND HWRF SLIGHTLY LOWER AT 95 KNOTS, LENDING OVERALL MEDIUM CONFIDENCE WITH THE JTWC INTENSITY FORECAST. FORECAST CONFIDENCE: TRACK 0 - 72 HR: HIGH TRACK 72-120 HR: LOW INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN