WDPN32 PGTW 071500 AMD MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 19W (CHANTHU) WARNING NR 006A AMENDED// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 16.3N 134.6E INITIAL INTENSITY: 85 KTS GEOGRAPHIC REFERENCE: 720 NM SOUTH-SOUTHEAST OF KADENA AB MOVEMENT PAST 6 HOURS: WESTWARD AT 11 KTS SIGNIFICANT WAVE HEIGHT: 28 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: THE 1200Z FORECAST HAS BEEN AMENDED TO REFLECT THE ONGOING EXTREME RAPID INTENSIFICATION OF THE SYSTEM. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY AT THE 1200Z HOUR SHOWED THAT THE SYSTEM WAS CONTINUING TO INTENSIFY WITH STRONG CONVECTIVE HOT TOWERS WRAPPING AROUND A WARM SPOT IN THE EIR IMAGERY. EIR IMAGERY SUBSEQUENT TO THE 1200Z HOUR DEPICTED THE RAPID APPEARANCE OF A WELL DEFINED, PINHOLE EYE, SUPPORTING THE ONSET OF EXTREME RAPID INTENSIFICATION. THE INITIAL POSITION WAS PLACED WITH HIGH CONFIDENCE BASED ON A 071107Z ASCAT-A BULLSEYE, WHICH ALIGNED PERFECTLY WITH THE WARM SPOT IN THE EIR. THE INITIAL INTENSITY AT THE 1200Z HOUR WAS HEDGED SLIGHTLY HIGHER THAN AGENCY SUBJECTIVE AND AUTOMATED OBJECTIVE FIX DATA AND SUBSEQUENTLY INCREASED FAR ABOVE THE 1200Z FIXES, AND NOW SET AT 85 KNOTS. THE KNES 1200Z FIX HAS BEEN CORRECTED TO T5.0. INTERESTINGLY, WHILE SUBSEQUENT 1500Z FIXES WERE AS HIGH AT T5.5 (PGTW) WITH HIGHER DATA T-NUMBERS, THE ADT HAS YET TO PICK UP ON THE EYE AND REMAINS AT T3.5. AS EVIDENCED BY THE RAPID INTENSIFICATION, TY 19W IS COCOONED IN A VERY FAVORABLE ENVIRONMENT WITH LOW VWS, VERY WARM SSTS AND RADIAL OUTFLOW. OCEAN HEAT CONTENT (OHC) IN THE AREA REMAINS VERY HIGH WITH VALUES BETWEEN 150-200 JOULES. INITIAL WIND RADII BASIS: SCATTEROMETER DATA. CURRENT STEERING MECHANISM: DEEP SUBTROPICAL RIDGE TO THE NORTH. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T4.0 - 65 KTS RJTD: T3.5 - 55 KTS RCTP: T4.0 - 65 KTS KNES: T5.0 - 90 KTS CIMSS ADT: 57 KTS AT 071140Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE VWS: 5-10 KTS SST: 29-30 CELSIUS OUTFLOW: STRONG RADIAL OTHER FACTORS: WHILE THE RADIAL OUTFLOW IS STRONG, IT IS LIMITED IN EXTENT DUE TO THE SMALL OVERALL STRUCTURE OF THE SYSTEM. ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: HIGH 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THIS FORECAST IS AMENDED TO INCREASE THE INITIAL INTENSITY AS WELL AS THE FORECAST INTENSITY. FORECAST DISCUSSION: TY 19W IS FORECAST TO TRACK WEST-NORTHWEST THROUGH TAU 24, THEN TURNING GRADUALLY MORE NORTHWESTWARD THROUGH THE REMAINDER OF THE FORECAST PERIOD AS THE STR REORIENTS SLIGHTLY AND A WEAKNESS DEVELOPS IN THE RIDGE TO THE NORTH OF TAIWAN. AS EVIDENCED BY THE ONGOING DRAMATIC IMPROVEMENTS IN THE EIR AND THE DEVELOPMENT OF A PINHOLE EYE, THE SYSTEM IS UNDERGOING A PERIOD OF EXTREME RAPID INTENSIFICATION (ERI). ENVIRONMENTAL CONDITIONS ARE EXPECTED TO REMAIN VERY FAVORABLE FOR ADDITIONAL RI, OR EVEN ERI, OVER THE NEXT 36 HOURS, EXPECTED TO PEAK AT OR ABOVE 130 KNOTS BY TAU 36. THE SYSTEM WILL TRACK OVER VERY WARM, VERY HIGH OHC WATERS FOR THE NEXT 24 HOURS, THEN MOVE INTO AN AREA OF LOWER OHC. MEANWHILE THE VWS REMAINS LOW AND THE SMALL AREA OF RADIAL OUTFLOW OVER THE SYSTEM REMAINS FIRMLY IN PLACE. THE RAPID INTENSIFICATION PREDICTION AID (RIPA) CONTINUES TO BE TRIGGERED THROUGH TAU 36. THEN IT IS LIKELY TO EXPERIENCE AN EYEWALL REPLACEMENT CYCLE WHICH WILL DECREASE THE INTENSITY SLIGHTLY NEAR TAU 48. ANOTHER ROUND OF INTENSIFICATION IS EXPECTED AFTER TAU 48, TO A PEAK OF 130 KNOTS AT TAU 72 AS THE SYSTEM MOVES OVER ANOTHER AREA OF HIGH OHC, WHILE THE OTHER PARAMETERS REMAIN FAVORABLE. THEREAFTER, DECREASING SSTS AND OHC, AND INCREASING MID-LEVEL VWS WILL OFFSET THE DEVELOPMENT OF A MODERATE POLEWARD OUTFLOW CHANNEL, AND LEAD TO SLOW BUT STEADY WEAKENING THROUGH TAU 120. TS 18W (CONSON) IS LOCATED 700NM TO THE WEST-SOUTHWEST. THE TWO SYSTEMS ARE EXPECTED TO CLOSE WITHIN APPROXIMATELY 500NM BY TAU 72 BUT THE PROBABILITY OF BINARY INTERACTION REMAINS LOW DUE TO THE COMPACT NATURE OF THE TWO SYSTEMS. MODEL DISCUSSION: NUMERICAL TRACK GUIDANCE HAS COME INTO BETTER AGREEMENT SINCE THE PREVIOUS RUN. MODEL SPREAD IS 100NM AT TAU 48. GFS REMAINS THE EQUATORWARD OUTLIER IN THE NEAR TERM, THOUGH OVERALL IT HAS COME INTO BETTER AGREEMENT WITH THE REMAINDER OF THE CONSENSUS MEMBERS. AFTER TAU 48, WITH THE EXCEPTION OF NAVGEM, THE GUIDANCE NOW AGREES ON A TRACK ACROSS TAIWAN, INSTEAD OF THE EARLIER GFS AND HWRF DEPICTIONS SHOWING A SHARP TURN NORTHWARD. GFS AND HWRF STILL SHOW A NORTHWARD TURN, BUT NOW DO SO AFTER CROSSING TAIWAN. SO THE RUN TO RUN INCONSISTENCIES STILL REMAIN, AND THUS WHILE THE JTWC FORECAST TRACK REMAINS CONSISTENT, THERE IS LOW CONFIDENCE IN THE EXTENDED FORECAST, THUS ONLY MEDIUM CONFIDENCE. INTENSITY GUIDANCE IS MIXED, WITH ALL OF THE RAPID INTENSIFICATION GUIDANCE TRIGGERED, WHILE GFS REMAIN LUKEWARM TO INTENSIFICATION. THE JTWC FORECAST IS ABOVE ALL THE GUIDANCE INCLUDING THE RI GUIDANCE THROUGH TAU 36, THEN TRACKS CLOSEST TO THE COAMPS-TC THROUGH THE REMAINDER OF THE FORECAST. CONFIDENCE REMAINS MEDIUM HOWEVER, IN LIGHT OF THE EXTREMELY FAST RATE INTENSIFICATION BEING OBSERVED, AND THE UNCERTAINTY IN THE TIMING OF LIKELY EYEWALL REPLACEMENT CYCLES. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM TRACK 72-120 HR: LOW INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: LOW 4. JUSTIFICATION FOR AMENDMENT: UPDATED INITIAL INTENSITY AND FORECAST INTENSITY.// NNNN