WDPN31 PGTW 050300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 12W (YAGI) WARNING NR 015// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 19.1N 115.8E INITIAL INTENSITY: 130 KTS GEOGRAPHIC REFERENCE: 212 NM SOUTH-SOUTHEAST OF HONG KONG MOVEMENT PAST 6 HOURS: WESTWARD AT 05 KTS SIGNIFICANT WAVE HEIGHT: 42 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A WELL DEFINED SUPER TYPHOON (STY) 12W YAGI, WITH A SHARPLY-OUTLINED EYE. STY 12W IS CURRENTLY STILL TRACKING WESTWARD, ALTHOUGH AT A SLIGHTLY SLOWER PACE THAN THE PREVIOUS WARNING CYCLE. THE EYE FEATURE IS CURRENTLY APPROXIMATELY 15 NM WIDE WITH A TEMPERATURE OF 0 CELSIUS. INTENSE UPPER LEVEL DIVERGENCE IS STILL ALLOWING FOR A RADIAL OUTFLOW, WITH PREDOMINANTLY STRONG EQUATORWARD COMPONENT. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE DEFINED EYE IN THE EIR LOOP. THE INITIAL INTENSITY OF 130 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE MAJORITY OF AGENCY AND AUTOMATED DVORAK ESTIMATES LISTED BELOW. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE TO THE NORTH AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T6.5 - 127 KTS RJTD: T7.0 - 140 KTS RCTP: T6.5 - 127 KTS KNES: T6.5 - 127 KTS DEMS: T6.5 - 127 KTS CIMSS SATCON: 128 KTS AT 042030Z CIMSS ADT: 134 KTS AT 042320Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 5-10 KTS SST: 30-31 CELSIUS OUTFLOW: STRONG 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: STY 12W IS FORECAST TO TRACK WEST-NORTHWESTWARD, PASSING THROUGH THE LEIZHOU (LUICHOW) PENINSULA, JUST NORTH OF HAINAN BETWEEN TAU 36 AND 48, FOLLOWED BY THE TRANSIT OVER WARM WATERS OF THE GULF OF TONKIN. STY YAGI IS STILL FORECAST TO MAKE LANDFALL OVER NORTHERN VIETNAM. AS FOR THE PREVIOUS WARNING, THE CURRENT TRACK PLACES THE STY YAGI JUST NORTH OF HANOI, WITH THE MAIN STEERING MECHANISM BEING A BROAD SUBTROPICAL RIDGE (STR) TO THE NORTH OF THE SYSTEM. STY YAGI MAINTAINS CAPABILITY FOR SLIGHT INTENSIFICATION OVER THE NEXT 12 HOURS, GIVEN THE HIGHLY FAVORABLE ENVIRONMENT; HOWEVER, AFTERWARDS IT IS FORECAST TO WEAKEN AS IT CROSSES THE LEIZHOU (LUICHOW) PENINSULA. AS STY YAGI ENTER THE GULF OF TONKIN IT WILL ONCE AGAIN ENCOUNTER VERY HIGH SSTS COMBINED WITH ELEVATED OCEAN HEAT CONTENT VALUES, OFFSET HOWEVER BY A DECREASED UPPER LEVEL DIVERGENCE. AS SOON AS THE SYSTEM MAKES LANDFALL, IT IS FORECAST TO RAPIDLY WEAKEN, PARTICULARLY IN RESPONSE TO THE INTERACTION WITH THE NORTHERN EXTENT OF THE ANNAMITE MOUNTAIN RANGE. MODEL DISCUSSION: MODEL GUIDANCE REMAINS IN GOOD AGREEMENT, WITH MAJORITY OF THE MODELS TRACKING THE SYSTEM ACROSS THE LEIZHOU (LUICHOW) PENINSULA INTO THE NORTHERN VIETNAM. SINCE LAST WARNING HOWEVER, THE SPREAD BETWEEN THE CONSENSUS MEMBERS INCREASED SLIGHTLY, TO APPROXIMATELY 80 NM CROSS-TRACK SPREAD AT TAU 36, WITH TWO MEMBERS TRACKING OVER THE NORTHERN TIP OF THE ISLAND OF HAINAN. JTWC FORECAST IS PLACED CLOSE TO THE MULTI-MODEL CONSENSUS, WITH MEDIUM CONFIDENCE OUT TO TAU 72. FOLLOWING TAU 72 SOME ADDITIONAL UNCERTAINTY REMAINS IN TERMS OF THE INTERACTION BETWEEN THE STY 12W AND THE IMPACTS OF STR AND THE TERRAIN. AS FAR AS INTENSITY GUIDANCE, CURRENT MODEL GUIDANCE SHOWS STEADY AND MINOR WEAKENING OVER THE NEXT 24 HOURS, FOLLOWED BY DRASTIC DROP IN INTENSITY AFTERWARDS. THE JTWC INTENSITY GUIDANCE IS ASSESSED TIGHTLY MATCHING THE MULTI-MODEL CONSENSUS OUT TO TAU 24, WITH ESTIMATES SLIGHTLY ABOVE THE CONSENSUS AFTERWARDS, AS THE ENVIRONMENT INDICATES FAVORABLE OR MARGINALLY FAVORABLE CONDITIONS TO CONTINUE INFLUENCING THE SYSTEM. FORECAST CONFIDENCE: TRACK 0 - 72 HR: HIGH TRACK 72-120 HR: MEDIUM INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN