WDXS32 PGTW 162100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 06S (ANGGREK) WARNING NR 004// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 9.5S 94.2E INITIAL INTENSITY: 45 KTS GEOGRAPHIC REFERENCE: 315 NM NORTHWEST OF COCOS ISLANDS MOVEMENT PAST 6 HOURS: EAST-NORTHEASTWARD AT 02 KTS SIGNIFICANT WAVE HEIGHT: 16 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL CYCLONE 06S (ANGGREK) MAINTAINING A VERY ASYMMETRIC CONVECTIVE STRUCTURE AS IT SLOWLY TRACKED EASTWARD OVER THE PAST 12 HOURS AT 2KTS. A MOSTLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) IS OBSERVED THROUGHOUT THE EASTERN SEMICIRCLE WITH LOW AND MID-LEVEL CLOUD BANDS WRAPPING IN TIGHTLY TO THE LLCC, LACKING DEEP CONVECTIVE ELEMENTS LIKELY DUE TO THE PERSISTING MID LEVEL EASTERLY SHEAR (10-15KTS). THE WESTERN PERIPHERY REMAINS PLENTIFULLY CLUTTERED WITH DEEP CONVECTION AND IN THE NORTHWESTERN QUADRANT LARGE SPIRAL COULD BANDS PROTRUDE TO THE UPPERMOST LAYERS OF THE ATMOSPHERE. THE ENVIRONMENT IS ASSESSED AS MARGINALLY FAVORABLE FOR FURTHER DEVELOPMENT, WITH LOW TO MODERATE (10-17KTS) VERTICAL WIND SHEAR (VWS), CONDUCIVE (28-29 C) SEA SURFACE TEMPERATURES (SST), AND MODERATE WESTWARD TO EQUATORWARD DIVERGENT OUTFLOW ALOFT. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON AN EXPOSED LLCC OBSERVED IN A 161800Z HIMAWARI-9 EIR SATELLITE IMAGE. THE INITIAL INTENSITY OF 45 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE SUBJECTIVE AND OBJECTIVE INTENSITY ESTIMATES LISTED BELOW. INITIAL WIND RADII BASIS: SCATTEROMETER DATA CURRENT STEERING MECHANISM: BUILDING NER NORTH OF TC 06S AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T3.0 - 45 KTS KNES: T3.0 - 45 KTS CIMSS SATCON: 40 KTS AT 161800Z CIMSS ADT: 35 KTS AT 161800Z CIMSS AIDT: 34 KTS AT 161800Z CIMSS DPRINT: 36 KTS AT 161800Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 10-15 KTS SST: 28-29 CELSIUS OUTFLOW: MODERATE EQUATORWARD ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: MEDIUM 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TC 06S (ANGGREK) IS ANTICIPATED TO BEGIN TRACKING SOUTHWARD UNDER THE STEERING INFLUENCE OF A BUILDING NEAR EQUATORIAL RIDGE NORTH OF THE SYSTEM. ON THIS SOUTHBOUND TRACK, A MARGINALLY FAVORABLE ENVIRONMENT IS ANTICIPATED TO ALLOW FOR A SLIGHT GAIN IN INTENSITY, NEARING 60KTS BY TAU 24. AS THE SYSTEM CONTINUES TO TRACK SOUTHWARD, THE PRIMARY STEERING INFLUENCE SHIFTS TO A SUBTROPICAL RIDGE AHEAD OF THE SYSTEMS PATH (SOUTH OF THE TC). THIS FEATURE SLOWLY TURNS THE SYSTEM WESTWARD BY TAU 120. THROUGHOUT THE DURATION FROM TAU 36 TO TAU 120, THE INFLUENCE OF RELATIVELY DRY AIR (LESS THAN 50 PERCENT RH) IS ANTICIPATED TO GRADUALLY ENTRAIN THE SYSTEM, WEAKENING THE TC AND LOWERING INTENSITY. MODEL DISCUSSION: GLOBAL NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT THAT TC 06S (ANGGREK) WILL GENERAL TRACK SOUTHWARD WHILE SLOWLY TURNING TO AN EASTWARD TRACK BY TAU 120. DISREGARDING MOGREPS AND ECMWF ENSEMBLE MEAN JTWC CONSENSUS MEMBERS, THE CROSS- TRACK SPREAD AT TAU 72 IS APPROXIMATELY 33NM, SHOWING EXCEPTIONAL AGREEMENT IN TRACK PATTERN. THE GREATEST INCONSISTENCY BETWEEN MEMBERS IS SHOWN IN ALONG-TRACK SPREAD, WHICH IS APPROXIMATELY 235NM WITH ECMWF ENSEMBLE MEAN REMOVED FROM CALCULATION. INTENSITY GUIDANCE PAIRS WELL WITH THE ENVIRONMENTAL ASSESSMENT OF MARGINALLY FAVORABLE, AND SUGGESTS A SLIGHT INTENSIFICATION (UP TO NEAR 60KT INTENSITY) IS LIKELY TO OCCUR THROUGH TAU 24, FOLLOWED BY A GRADUAL WEAKENING TREND THROUGH TAU 120. WITH BOTH TRACK AND INTENSITY MODEL GUIDANCE SHOWING A COUPLE OF OUTLIERS TO THE DATA PRESENTED, THE OVERALL CONFIDENCE OF THIS FORECAST IS MEDIUM. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM TRACK 72-120 HR: MEDIUM INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN