WDPN32 PGTW 180300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 29W (CHAMPI) WARNING NR 015// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 13.1N 143.4E INITIAL INTENSITY: 130 KTS GEOGRAPHIC REFERENCE: 72 NM WEST-SOUTHWEST OF NAVSTA GUAM MOVEMENT PAST 6 HOURS: WESTWARD AT 14 KTS SIGNIFICANT WAVE HEIGHT: 47 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS SUPER TYPHOON (STY) 29W (CHAMPI) WITH A CLOUD FREE EYE THAT HAS WARMED TO 20 C AND A COMPACT CDO WITH CLOUD TOPS THAT HAVE ALSO SLIGHTLY WARMED, PARTICULARLY IN THE SOUTHEASTERN QUADRANT, WHILE A MORE DISPLACED CONVECTIVE BAND ON THE WESTERN FLANK HAS BEGUN TO DEVELOP. AN EYEWALL REPLACEMENT CYCLE (ERC) MAY HAVE RESUMED AS A 172152Z SSMIS PASS REVEALS A PARTIAL SECONDARY EYEWALL STRONGEST IN THE NORTHEASTERN QUADRANT AND VISIBLE BUT WEAKER ON THE SOUTHERN SEMICIRCLE, WHILE STILL FULLY OPEN IN THE NORTHWESTERN QUADRANT. A SIMILAR DEPICTION IS SUPPORTED IN ANIMATED RADAR IMAGERY FROM GUAM, AND A 30 NM MOAT BETWEEN THE TWO EYEWALLS. ENVIRONMENTAL CONDITIONS ARE ASSESSED AS HIGHLY FAVORABLE WITH WARM (28-29 C) SEA SURFACE TEMPERATURES (SSTS), LOW TO MODERATE (15-20 KTS) VERTICAL WIND SHEAR (VWS), AND STRONG RADIAL OUTFLOW ALOFT AS WELL AS AN EQUATORWARD OUTFLOW CHANNEL. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE EYE IN MSI AND RADAR IMAGERY. THE INITIAL INTENSITY IS ASSESSED WITH HIGH CONFIDENCE, HEDGED SLIGHTLY LOWER THAN THE AGENCY DVORAK FIXES AND OBJECTIVE ESTIMATES DUE TO THE ASSESSED RESUMPTION OF ERC AND RESULTANT TEMPORARY DETERIORATION OF THE CDO. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: EASTWARD EXTENSION OF A SUBTROPICAL RIDGE CENTERED TO THE NORTHWEST AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T7.0 - 140 KTS RJTD: T7.0 - 140 KTS RCTP: T7.0 - 140 KTS CIMSS SATCON: 134 KTS AT 172152Z CIMSS ADT: 137 KTS AT 172340Z CIMSS AIDT: 140 KTS AT 172340Z CIMSS D-MINT: 116 KTS AT 172313Z CIMSS D-PRINT: 137 KTS AT 172340Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE VWS: 15-20 KTS SST: 28-29 CELSIUS OUTFLOW: STRONG RADIAL OTHER FACTORS: EQUATORWARD OUTFLOW CHANNEL AND 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: CHAMPI HAS CONTINUED ON A WESTWARD TRACK AS THE EASTWARD EXTENSION OF THE SUBTROPICAL RIDGE (STR) CENTERED FAR TO THE WEST-NORTHWEST MAINTAINS STEERING CONTROL. BY TAU 12, THE EXTENSION WILL REFORM INTO A SEPARATE STR, AND THE RESULTANT WEAKNESS IN THE RIDGING COMPLEX BETWEEN THE NEW STR AND THE WESTERN STR WILL CAUSE 29W TO TURN POLEWARD FOR THE REMAINDER OF THE FORECAST PERIOD, WITH THE NEWLY FORMED STR BECOMING THE DOMINANT STEERING FACTOR. REGARDING INTENSITY, 29W IS EXPECTED TO GRADUALLY INTENSIFY AND PLATEAU FOR THE NEXT 72 HOURS AS ENVIRONMENTAL CONDITIONS REMAIN HIGHLY FAVORABLE. A PEAK INTENSITY OF 140 KTS IS EXPECTED BETWEEN TAUS 24 AND 48 AS VWS WILL ABATE TO UNDER 10 KTS AND 29W ENTERS AN AREA OF HIGH (140-150 KJ PER CM SQUARED) OCEAN HEAT CONTENT (OHC). HOWEVER, PROLONGED OR EVEN MULTIPLE ERCS ARE POSSIBLE DURING THIS TIME FRAME, WHICH ADDS UNCERTAINTY AND THE POTENTIAL FOR SHORT TERM FLUCTUATIONS ABOVE OR BELOW THE OFFICIAL INTENSITY FORECAST, DUE TO THE INHERENTLY DIFFICULT NATURE IN FORECASTING THESE INTERNAL DYNAMICS. BEYOND TAU 72, A GRADUAL WEAKENING TREND IS EXPECTED TO BEGIN AS 29W WILL SLIGHTLY SLOW IN TRACK SPEED, ENTER AN AREA OF LOWER OHC, AND BEGIN UPWELLING COOLER SSTS. MODEL DISCUSSION: TRACK MODEL GUIDANCE IS IN GOOD AGREEMENT FOR THE FORECAST PERIOD, WITH A CROSS-TRACK AND ALONG-TRACK SPREAD OF 145 NM AT TAU 120, COMPRISED OF GOOGLE DEEPMIND AS THE MOST POLEWARD SOLUTION AND THE GEFS ENSEMBLE MEAN BEING THE MOST EQUATORWARD SOLUTION. THE MAJORITY OF AI-BASED MODELS CONTINUE TO MAKE UP THE NORTHERN SIDE OF THE GUIDANCE PACKAGE, WHILE PHYSICS-BASED MODELS AS WELL AS THE AI GEFS ENSEMBLE MEAN FAVOR THE SOUTHERN SIDE. ENSEMBLE MODEL ANALYSIS REFLECTS THIS SPREAD, WITH PHYSICS-BASED MODEL MEMBERS CONTINUING TO FAVOR A FARTHER SOUTH TRACK, WHILE AI- BASED MODELS HEDGE FARTHER NORTH, INCREASING THE UNCERTAINTY NEAR THE END OF THE FORECAST PERIOD. THE OFFICIAL JTWC FORECAST TRACK IS PLACED WITH HIGH CONFIDENCE OUT TO TAU 72 AND MEDIUM CONFIDENCE THEREAFTER, CLOSELY IN LINE WITH THE MULTI-MODEL AND AI CONSENSUS, HEDGED SLIGHTLY CLOSER TO THE AI CONSENSUS IN TAUS 96 AND 120. MODEL INTENSITY GUIDANCE REMAINS IN GOOD AGREEMENT ON A SLIGHT INTENSIFICATION OR PLATEAU OUT TO TAUS 60 TO 72, WITH THE EXCEPTION OF THE LOW END OUTLIERS OF COAMPS-TC (NAVGEM BASED) AND GFS. NOTABLY, HAFS-A IS NOW BELOW THE MULTI-MODEL CONSENSUS BEYOND TAU 12 WHILE BOTH GOOGLE DEEPMIND MODELS MAINTAIN PEAKS OF 145-150 KTS. AFTER TAU 72, ALL MODELS DEPICT THE STEADY WEAKENING TREND FOR THE REMAINDER OF THE FORECAST PERIOD. THE HAFS-A MODEL FIELDS PREDICT ANOTHER ERC TO OCCUR BETWEEN TAUS 60 AND 96 AND A STEEPER DECLINE IN INTENSITY ONCE IT BEGINS. THE OFFICIAL JTWC FORECAST INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE OUT TO TAU 72 DUE TO THE UNCERTAINTIES DISCUSSED ABOVE AND LOW CONFIDENCE THEREAFTER, CLOSELY IN LINE WITH THE OPERATIONAL GOOGLE DEEPMIND AND SLIGHTLY ABOVE, BUT REFLECTING THE SHAPE OF THE MULTI- MODEL CONSENSUS. FORECAST CONFIDENCE: TRACK 00-72 HR: HIGH TRACK 72-120 HR: MEDIUM INTENSITY 00-72 HR: MEDIUM INTENSITY 72-120 HR: LOW// NNNN