WDXS32 PGTW 040900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 10S (TEN) WARNING NR 001// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 17.8S 83.8E INITIAL INTENSITY: 35 KTS GEOGRAPHIC REFERENCE: 921 NM SOUTHEAST OF DIEGO GARCIA MOVEMENT PAST 6 HOURS: SOUTH-SOUTHEASTWARD AT 06 KTS SIGNIFICANT WAVE HEIGHT: 12 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A CONSOLIDATING SYSTEM WITH WEAK FORMATIVE BANDS WRAPPING INTO AN OBSCURED LOW LEVEL CIRCULATION (LLC). THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON A DEFINED LLC FEATURE IN THE 040355Z GPM MICROWAVE IMAGE. THE INITIAL INTENSITY OF 35KTS IS BASED ON RECENT SMAP AND HSCAT DATA AND CONSISTENT WITH THE IMPROVED 6-HR CONVECTIVE STRUCTURE. ANALYSIS INDICATES A MARGINALLY FAVORABLE ENVIRONMENT WITH STRONG POLEWARD OUTFLOW AND WARM SST OFFSET BY MODERATE (15-20KTS) VWS. THE CYCLONE IS TRACKING ALONG THE NORTHWEST PERIPHERY OF THE STR TO THE SOUTHEAST. INITIAL WIND RADII BASIS: SCATTEROMETER DATA. CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE SOUTHEAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T2.0 - 30 KTS FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 15-20 KTS SST: 28-29 CELSIUS OUTFLOW: STRONG POLEWARD ANALYSIS CONFIDENCE: INITIAL POSITION: MEDIUM INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: MEDIUM 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY. FORECAST DISCUSSION: TC 10S WILL TRACK MORE SOUTHWESTWARD UNDER THE STEERING INFLUENCE OF THE STR FOR THE DURATION OF THE FORECAST. THE MARGINAL ENVIRONMENT WILL FUEL SLOW INTENSIFICATION TO 45KTS AT TAUS 24-36. AFTERWARD, INCREASING VWS WILL REDUCE IT TO 40KTS AND HINDER ANY FURTHER INTENSIFICATION UP TO TAU 96. AFTER TAU 96, THE ADDITION OF COOLING SST (26C) WILL BEGIN TO DISSIPATE THE SYSTEM AND BY TAU 120, WILL BE REDUCED TO 35KTS. MODEL DISCUSSION: NUMERICAL MODELS ARE IN FAIRLY GOOD AGREEMENT BUT GIVEN THE FORMATIVE NATURE OF THE SYSTEM, THERE IS ONLY MEDIUM CONFIDENCE IN THE JTWC INITIAL FORECAST TRACK THAT IS LAID ON TOP OF THE MODEL CONSENSUS. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM TRACK 72-120 HR: MEDIUM INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN