WDXS31 PGTW 060900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 21S (OLGA) WARNING NR 003// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 13.1S 120.2E INITIAL INTENSITY: 50 KTS GEOGRAPHIC REFERENCE: 653 NM NORTH-NORTHEAST OF LEARMONTH, AUSTRALIA MOVEMENT PAST 6 HOURS: SOUTHWARD AT 04 KTS SIGNIFICANT WAVE HEIGHT: 16 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TROPICAL CYCLONE (TC) 21S (OLGA) HAS CONSOLIDATED RAPIDLY WITH TIGHTLY-CURVED BANDING WRAPPING INTO A DEFINED LOW-LEVEL CIRCULATION CENTER (LLCC) IN RECENT ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI). A 060533Z AMSR2 36 GHZ COLOR COMPOSITE MICROWAVE IMAGE REVEALS A CYAN RING FEATURE (WHICH IS TYPICALLY A PRECURSOR TO RAPID INTENSIFICATION) SURROUNDING A SYMMETRIC, WELL-DEFINED MICROWAVE EYE FEATURE. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE MSI AND AMSR2 IMAGERY. ALTHOUGH THERE IS DRY AIR PRESENT OVER THE WESTERN PERIPHERY OF THE SYSTEM, THERE IS A DEEP MOIST CORE AS WELL AS ROBUST POLEWARD OUTFLOW, LOW VERTICAL WIND SHEAR AND WARM SST VALUES. THE INITIAL INTENSITY OF 50 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON SUBJECTIVE DVORAK INTENSITY ESTIMATES RANGING FROM 45 TO 55 KNOTS. CIMSS OBJECTIVE INTENSITY ESTIMATES HAVE INCREASED MARKEDLY, WITH DPRINT, DMINT AND SATCON RANGING FROM 46 TO 53 KNOTS. INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR) POSITIONED TO THE EAST AND SOUTHEAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T3.0 - 45 KTS KNES: T3.5 - 55 KTS APRF: T3.5 - 55 KTS CIMSS SATCON: 53 KTS AT 060533Z CIMSS ADT: 51 KTS AT 060530Z CIMSS AIDT: 40 KTS AT 060700Z CIMSS DPRINT: 46 KTS AT 060600Z CIMSS DMINT: 49 KTS AT 060533Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE VWS: 5-10 KTS SST: 29-30 CELSIUS OUTFLOW: MODERATE RADIAL, WITH ENHANCED POLEWARD OUTFLOW ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: HIGH INITIAL WIND RADII: MEDIUM 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: INCREASED THE PEAK INTENSITY TO 80 KNOTS DUE TO THE SYSTEM'S RAPID CONSOLIDATION. FORECAST DISCUSSION: TC 21S IS TRACKING SLOWLY SOUTHWARD ALONG THE WESTERN PERIPHERY OF THE STR BUT IS EXPECTED TO TURN SOUTHWESTWARD TO WEST-SOUTHWESTWARD AFTER TAU 36 ALONG AN EXTENSION OF THE STR POSITIONED OVER NORTHWESTERN AUSTRALIA. TC OLGA WILL CONTINUE TRACKING GENERALLY WEST-SOUTHWESTWARD THROUGH TAU 96, WITH A STRONG HIGH BUILDING TO THE SOUTH. ENVIRONMENTAL CONDITIONS WILL REMAIN CONDUCIVE THROUGH TAU 24 ALLOWING FOR A SHORT PERIOD OF RAPID INTENSIFICATION (RI), WITH A PEAK INTENSITY OF 80 KNOTS BY TAU 24. ENVIRONMENTAL CONDITIONS ARE EXPECTED TO DEGRADE QUICKLY AFTER TAU 24, WITH INCREASING VERTICAL WIND SHEAR (VWS) OF 25 KNOTS NEAR TAU 24 TO 40 KNOTS BY TAU 72. MID- TO UPPER-LEVEL DRY AIR ENTRAINMENT WILL INCREASE SIGNIFICANTLY OVER THE NEXT TWO DAYS, WITH THE SYSTEM EMBEDDED WITHIN A VERY DRY, HOSTILE ENVIRONMENT BY TAU 72, WHICH WILL LEAD TO RAPID WEAKENING AND DISSIPATION BY TAU 96. MODEL DISCUSSION: WITH THE EXCEPTION OF NAVGEM, WHICH SHOWS A TRACK RECURVING INTO NORTHWEST AUSTRALIA, NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT WITH A 138 NM CROSS-TRACK SPREAD IN SOLUTIONS AT TAU 72 AND 184 NM AT TAU 96. BOTH THE 051800Z ECMWF ENSEMBLE (EPS) AND THE 060000Z GFS ENSEMBLE (GEFS) INDICATE A SIMILAR TRACK SPREAD. RELIABLE INTENSITY GUIDANCE CONSISTENTLY INDICATES A SHARP INTENSIFICATION TREND THROUGH TAU 24 WITH PEAK INTENSITIES RANGING FROM 60 TO 83 KNOTS THEN A PERIOD OF RAPID WEAKENING THROUGH TAU 96. RAPID INTENSIFICATION GUIDANCE HAS CONTINUED TO TRIGGER SUPPORTING THE ONGOING AND FORECAST RI PHASE. ADDITIONALLY, THE 060000Z COAMPS- TC INTENSITY ENSEMBLE INDICATES A 40 TO 50 PERCENT PROBABILITY OF RAPID INTENSIFICATION THROUGH TAU 18. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM TRACK 72-120 HR: MEDIUM INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN