WDPN32 PGTW 180900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 29W (CHAMPI) WARNING NR 016// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 13.1N 142.3E INITIAL INTENSITY: 130 KTS GEOGRAPHIC REFERENCE: 156 NM WEST-SOUTHWEST OF ANDERSEN AFB MOVEMENT PAST 6 HOURS: WESTWARD AT 12 KTS SIGNIFICANT WAVE HEIGHT: 50 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A RAPIDLY DETERIORATING SYSTEM; THE PREVIOUSLY WELL-RESOLVED, WARM EYE EYEWALL COMPLEX FILLED RAPIDLY POST-180300Z, BECOMING COMPLETELY OBSCURED BY 180400Z. CURRENT MSI AND ENHANCED INFRARED (EIR) LOOPS RESOLVE NO CLOUD-FREE EYE SIGNATURE; HOWEVER, VIGOROUS VORTICAL HOT TOWERS (VHTS) RESIDE ALONG THE SOUTHERN SECTOR OF A NASCENT, RE-CONSOLIDATING EYEWALL. A 180618Z GMI 89GHZ MICROWAVE PASS CONFIRMED AN ACTIVE SECONDARY EYEWALL FORMATION (SEF) EVENT, WITH THE CIMSS M-PERC HOVMOLLER DIAGRAM RESOLVING THE CONCENTRIC OUTER EYEWALL BAND ANCHORED APPROXIMATELY 40 KM DISTANT FROM THE LOW-LEVEL CIRCULATION CENTER (LLCC). IN ADDITION TO COMPLICATED ERC DYNAMICS, DRY MID-LEVEL AIR ENTRAINMENT IS VIGOROUSLY INTRUDING INTO THE CYCLONE'S INNER CORE FROM THE EAST. THIS THERMODYNAMIC EROSION IS CLEARLY RESOLVED IN HAFS-A RELATIVE HUMIDITY CROSS-SECTIONS AND COINCIDES WITH GMI BRIGHTNESS TEMPERATURE ANOMALIES. THE INITIAL POSITION IS ASSESSED WITH MEDIUM CONFIDENCE OWING TO THE OBSCURED LLCC, INTERPOLATED VIA REMNANT CORE CLOUD-TOP CURVATURE AND ACTIVE CONVECTIVE FLARES IN EIR. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE. POST-ANALYSIS OF EARLIER POSITIONS JUSTIFIED AN UPGRADE IN THE 180000Z INTENSITY TO 145 KNOTS. THE RECENT EYE COLLAPSE HAS INDUCED A STEEP DECAY IN THE MAJORITY OF OBJECTIVE ESTIMATES, EXCLUDING CIMSS ADT CI VALUES; HOWEVER, CONSTRAINTS ARE BEING APPLIED, AND RAW T-NUMBERS ARE SIGNIFICANTLY DEPRESSED. THE INITIAL INTENSITY IS SET CONSERVATIVELY AT 130 KNOTS BASED ON A SYNTHESIS OF THE MULTI-AGENCY ESTIMATES. THE SYNOPTIC ENVIRONMENT REMAINS FAVORABLE, CHARACTERIZED BY LOW DEEP-LAYER VWS, STRONG RADIAL OUTFLOW ALOFT, AND WARM SSTS; HOWEVER, THE ONGOING ERC AND ENTRAINMENT OF DRY AIR INTO THE CORE WILL DRAG THE SYSTEM INTO A TEMPORARY WEAKENING PHASE. INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK CURRENT STEERING MECHANISM: SOUTHERN FLANK OF AN EXTENSION OF A SUBTROPICAL RIDGE (STR) CENTERED NEAR HONG KONG. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T6.5 - 127 KTS RJTD: T7.0 - 140 KTS RCTP: T7.0 - 140 KTS CIMSS SATCON: 109 KTS AT 180500Z CIMSS ADT: 134 KTS AT 180540Z CIMSS AIDT: 126 KTS AT 180540Z CIMSS D-MINT: 121 KTS AT 180618Z CIMSS D-PRINT: 124 KTS AT 180600Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 10-15 KTS SST: 29-30 CELSIUS OUTFLOW: STRONG DUAL-CHANNEL OTHER FACTORS: EYEWALL REPLACEMENT CYCLE (ERC). 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: SUPER TYPHOON (STY) 29W IS FORECAST TO GRADUALLY TURN NORTHWESTWARD OVER THE NEXT 12 HOURS AND MAINTAIN THIS STEADY TRAJECTORY THROUGHOUT THE FORECAST. THE CONTROLLING SYNOPTIC DRIVER IS THE RIDGE EXTENSION CENTERED NEAR HONG KONG. AROUND TAU 24, THE STR IS PROJECTED TO SEPARATE INTO TWO DISTINCT HIGH-PRESSURE CENTERS (ONE NORTHEAST OF THE CYCLONE AND A LARGER CELL NEAR HONG KONG). THE RESULTANT COL WEAKNESS WILL INDUCE A SLIGHT DECELERATION IN TRANSLATION SPEED FROM TAU 24 TO TAU 36. POST-TAU 36, 29W WILL RE-ACCELERATE TO 12-13 KNOTS AS THE WESTERN RIDGE CELL BECOMES THE PRIMARY STEERING INFLUENCE. BY TAU 72, A MID-LATITUDE SHORTWAVE TROUGH PASSES OVER THE KOREAN PENINSULA, FRACTURING THE RIDGE AND ESTABLISHING A STEERING WEAKNESS ACROSS THE EAST CHINA SEA. AS 29W ENTERS THE EQUATORWARD QUADRANT OF THIS COL NEAR TAU 72, IT WILL DECELERATE MARKEDLY UNDER A RELAXED PRESSURE GRADIENT. WHILE THE BASELINE TRACK PROG STRETCHES NORTHWESTWARD THROUGH TAU 120, GUIDANCE BIFURCATES SHARPLY POST-TAU 72, SENSITIVE TO THE DEPTH OF THE APPROACHING TROUGH. ROUGHLY HALF OF THE CONSENSUS DEPICTS A RECURVATURE INTO THE EAST CHINA SEA, WHILE THE REMAINING MEMBERS TRACK THE CYCLONE ON A STRAIGHT TRAJECTORY TOWARDS SOUTHERN TAIWAN. REGARDING INTENSITY: THE COMBINED FORCES OF ERC DRY AIR ENTRAINMENT HAVE DEGRADED THE INNER CORE OVER THE PAST SIX HOURS. 29W IS FORECAST TO CONTINUE ITS TEMPORARY DECAY, BOTTOMING OUT NEAR 120 KNOTS AT TAU 12, PRIOR TO OUTER EYEWALL CONSOLIDATION AND REINTENSIFICATION. THE CYCLONE TRANSITS OVER A POOL OF ELEVATED OHC FROM TAU 24 TO TAU 48, WHICH SHOULD FUEL A SECONDARY INTENSITY PEAK OF AT LEAST 140 KNOTS. HOWEVER, INCIPIENT CYCLES OF SEF ARE HIGHLY PLAUSIBLE, WHICH WOULD MATERIALLY ALTER THE MAGNITUDE AND SHAPE OF THE INTENSITY CURVE. BEYOND TAU 72, AS TRANSLATION SPEEDS DECREASE, SELF-INDUCED COLD WATER UPWELLING COMBINED WITH INCREASING VWS WILL PROMPT A GRADUAL DECAY PROFILE AS THE CYCLONE APPROACHES TAIWAN. MODEL DISCUSSION: TRACK GUIDANCE IS IN STRONG AGREEMENT THROUGH TAU 72. CROSS-TRACK SPREAD IS MINIMAL THROUGH TAU 24, AND GRADUALLY INCREASES TO 90NM BY DAY THREE. UP TO THIS POINT IN THE FORECAST, THE ECMWF TRACKER IS POSITIONED ON THE SOUTHERN EDGE OF THE GUIDANCE ENVELOPE, WHILE THE GOOGLE DEEPMIND AND EC-AIFS AI ENSEMBLE ARE POSITIONED ON THE NORTHERN EDGE. TAU 72 IS THE INFLECTION POINT WHERE THE MODELS DIVERGE INTO TWO CAMPS. ALL OF THE AI MODELS BEGIN TO SPLIT OFF AND BREAK TO THE NORTH WITH THE TWO MENTIONED EARLIER BEING THE MOST AGGRESSIVE NORTH MOVERS THROUGH TAU 120. THE OTHER AI MODELS DEPICT A VERY SHALLOW TURN, JUST A BIT NORTH OF NORTHWEST THROUGH TAU 120. THE PHYSICS MODELS ALL CONTINUE STRAIGHT NORTHWESTWARD AT A SLIGHTLY FASTER SPEED OF ADVANCE. GEFS IS POSITIONED ON THE SOUTHERN EDGE, MOVING INTO THE LUZON STRAIT WHILE NAVGEM IS ON THE NORTHERN EDGE, MOVING TOWARDS CENTRAL TAIWAN, AT TAU 120. CROSS-TRACK SPREAD INCREASES TO 310NM BY TAU 120 BETWEEN THE OUTLIERS. THE EXPERIMENTAL JTWC SUPER-ENSEMBLE DEPICTS A STRONG BIFURCATION SCENARIO, WITH ROUGHLY HALF OF THE NEARLY 300 MEMBERS RECURVING AND THE OTHER MAINTAINING A STRAIGHT TRACK. THE JTWC FORECAST IS CONSISTENT WITH THE PREVIOUS TRACK FORECAST AND NEAR THE EC-AIFS TRACKER. INTENSITY GUIDANCE IS IN GOOD OVERALL AGREEMENT, WITH CTCX, COTC AND SHIPS SHOWING A SHARP DECREASE THROUGH TAU 12 FOLLOWED BY REINTENSIFICATION TO 130-140 KNOTS BY TAU 48 BEFORE RENEWED WEAKENING THROUGH THE END OF THE FORECAST. THE JTWC FORECAST IS PLACED NEAR THE CTCX TRACKER THROUGH THE FORECAST PERIOD. FORECAST CONFIDENCE: TRACK 00-72 HR: HIGH TRACK 72-120 HR: MEDIUM INTENSITY 00-72 HR: MEDIUM INTENSITY 72-120 HR: LOW// NNNN