WDXS31 PGTW 182100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 05S (DARIAN) WARNING NR 002// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 12.1S 93.1E INITIAL INTENSITY: 45 KTS GEOGRAPHIC REFERENCE: 225 NM WEST OF COCOS ISLANDS MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 04 KTS SIGNIFICANT WAVE HEIGHT: 18 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS AN OVERALL RAGGED SYSTEM WITH HINTS OF STRUCTURE ATTEMPTING TO TAKE PLACE, ALONG WITH EVIDENCE OF FEEDER BANDS IN THE EASTERN AND SOUTHERN SEMI-CIRCLES WRAPPING INTO AN ASSESSED LOW LEVEL CIRCULATION CENTER (LLCC). TC DARIAN IS UNDER AN AREA OF MODERATE (15-20 KTS) POLEWARD OUTFLOW ALOFT, LOW (10-15 KTS) VERTICAL WIND SHEAR, A STRONG 850 MB VORTICITY SIGNATURE AND WARM (26-27 C) SEA SURFACE TEMPERATURES. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED OF THE AFOREMENTIONED SATELLITE IMAGERY, AS WELL AS THE PGTW AND APRF FIXES. THE INITIAL INTENSITY OF 45 KNOTS IS SET WITH MEDIUM CONFIDENCE BASED THE PGTW DVORAK ESTIMATE OF 3.0, ADT OF 3.2, AND SET SLIGHTLY LOWER THAN THE AIDT VALUE OF 49 KNOTS AND SATCON VALUE OF 50 KTS. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: NEAR EQUATORIAL RIDGE TO THE NORTHEAST AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T3.0 - 45 KTS APRF: T3.0 - 45 KTS CIMSS SATCON: 50 KTS AT 181347Z CIMSS ADT: 49 KTS AT 181730Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 10-15 KTS SST: 26-27 CELSIUS OUTFLOW: MODERATE POLEWARD OTHER FACTORS: STRONG 850 MB VORTICITY SIGNATURE ANALYSIS CONFIDENCE: INITIAL POSITION: MEDIUM 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: AFTER OVERCOMING A SMALL PERIOD OF QUASI-STATIONARY LIKE BEHAVIOR, TC DARIAN HAS TRACKED SOUTHEASTWARD OVER THE PAST 12 HOURS AS THE NEAR EQUATORIAL RIDGE TO THE NORTHEAST HAS BUILT IN AND INFLUENCED ITS TRACK MOTION. BY TAUS 12 AND 24, TC 05S WILL MAKE A SOUTHWARD TURN AND GRADUALLY INCREASE IN INTENSITY TO 55 KTS AND 60 KTS RESPECTIVELY AS THE ENVIRONMENT WILL IMPROVE. BY TAU 36, THE SUBTROPICAL RIDGE (STR) TO THE SOUTH WILL BECOME THE DOMINATE STEERING MECHANISM AND THE SYSTEM WILL MAKE THE TURN SOUTH-SOUTHWESTWARD WHILE MAINTAINING ITS INTENSITY OF 60 KTS. THE INTENSITY IS NOT EXPECTED TO INCREASE AFTER THIS TIME DUE TO UPWELLING UNDER THE SYSTEM THAT WILL BRING THE SST SLIGHTLY BELOW 26 C. THIS UPWELLING IS DUE TO THE PREVIOUS QUASI-STATIONARY POSTURE AND SLOW MOVEMENT OF TC DARIAN DURING THE BEGINNING OF ITS FORECAST TRACK. BY TAUS 48 AND 72, THE SYSTEM WILL CONTINUE TO TURN AND HEAD ON A WEST-SOUTHWESTWARD TRACK ALONG THE NORTHERN PERIPHERY OF THE STR AND ITS INTENSITY WILL SLIGHTLY DECREASE FROM 60 KTS TO 55 KTS. THIS SLIGHT DECREASE IN INTENSITY TO DUE THE PRESENCE OF DRY AIR BEING WRAPPED AROUND THE SYSTEM, ALTHOUGH TC DARIAN IS EXPECTED TO HOLD ONTO ITS MOISTURE AND STAY COCOONED THROUGHOUT THE FORECAST PERIOD. BY TAU 120, THERE IS A SLIGHT INCREASE IN INTENSITY BACK UP TO 60 KTS DUE TO AN INCREASE IN WESTWARD AND POLEWARD UPPER-LEVEL OUTFLOW ALOFT. MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE REMAINS IN AGREEMENT OF A RECURVATE SCENARIO FOR TC DARIAN, HOWEVER, THEY ARE IN DISAGREEMENT OF THE ACTUAL TRACK TC 05S WILL TAKE TO ACHIEVE THIS RECURVE. THE JTWC TRACK IS SET WITH MEDIUM CONFIDENCE STARTING TO THE RIGHT OF CONSENSUS UP TO TAU 72. AFTER TAU 72, THE JTWC FORECAST TRACK IS SET LEFT OF CONSENSUS DUE TO THE CONSENSUS MEMBERS HAVING A HARD TIME DETERMINING THE STRENGTH AND PRESENCE OF THE STR AT THIS TIME. THE JTWC INTENSITY IS SET WITH MEDIUM CONFIDENCE FAVORING THE GFS AND COAMPS SOLUTIONS AS THE HWRF SOLUTION IS EXTREMELY AGGRESSIVE AND GOES IMMEDIATELY OFF THE CHART. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM TRACK 72-120 HR: MEDIUM INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: LOW// NNNN