WDPN32 PGTW 040900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 05W (FIVE) WARNING NR 002// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 19.6N 118.2E INITIAL INTENSITY: 30 KTS GEOGRAPHIC REFERENCE: 377 NM SOUTH-SOUTHWEST OF TAIPEI, TAIWAN MOVEMENT PAST 6 HOURS: WESTWARD AT 05 KTS SIGNIFICANT WAVE HEIGHT: 12 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A CONSOLIDATING LOW-LEVEL CIRCULATION (LLC), WITH IMPROVED CONVECTIVE BANDING DRIVEN BY THE IMPROVING DUAL CHANNEL OUTFLOW. A 040503Z AMSR2 37GHZ COLOR COMPOSITE MICROWAVE IMAGE REVEALS IMPROVED CONVECTIVE BANDING OVER THE SOUTHERN SEMICIRCLE, WRAPPING INTO THE NORTHERN QUADRANT. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE AMSR2 IMAGE AND ANIMATED MSI. THE INITIAL INTENSITY OF 30 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE PGTW DVORAK ESTIMATE OF T2.0 (30 KNOTS), WHICH IS ALIGNED BEST WITH THE INITIAL POSITION. THE HIGHER AGENCY ESTIMATES OF T2.5 (35 KNOTS) MAY BE POSITIONED TOO FAR SOUTHWEST INTO THE DEEP CONVECTION THUS YIELDING HIGHER ESTIMATES. A SHIP OBSERVATION AT 040400Z, APPROXIMATELY 109NM EAST (19.8N 120.3E), INDICATES SOUTHERLY WINDS AT 27 KNOTS (10-MINUTE AVERAGE), WHICH ALSO SUPPORTS THE INITIAL INTENSITY ASSESSMENT. INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND RADII). CURRENT STEERING MECHANISM: LOW-LEVEL SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTH. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T2.0 - 30 KTS RJTD: T1.5 - 25 KTS KNES: T2.5 - 35 KTS DEMS: T2.5 - 35 KTS CIMSS SATCON: 38 KTS AT 040700Z CIMSS ADT: 30 KTS AT 040530Z CIMSS AIDT: 31 KTS AT 040530Z CIMSS D-MINT: 37 KTS AT 040506Z CIMSS D-PRINT: 34 KTS AT 040630Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 5-10 KTS SST: 29-30 CELSIUS OUTFLOW: MODERATE DUAL-CHANNEL ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: HIGH INITIAL WIND RADII: NOT APPLICABLE 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TROPICAL DEPRESSION (TD) 05W IS FORECAST TO MEANDER SLOWLY WESTWARD TO WEST-NORTHWESTWARD UNDER THE STEERING INFLUENCE OF THE LOW-LEVEL STR TO THE NORTH THROUGH TAU 24. AFTER TAU 24, THE SYSTEM WILL INTENSIFY QUICKLY AND TRACK NORTH- NORTHEASTWARD ALONG THE BUILDING STR ENTRENCHED TO THE EAST. TD 05W SHOULD REACH A PEAK INTENSITY OF 75 KNOTS BY TAU 48 DUE TO ROBUST DUAL CHANNEL OUTFLOW AND WARM SST VALUES. AS THE SYSTEM TRACKS THROUGH THE TAIWAN STRAIT, IT SHOULD WEAKEN AS WARM, DRY AIR ADVECTS OFF THE MOUNTAINS OF TAIWAN AND ENTRAINS INTO THE SYSTEM'S CORE. AFTER TAU 72, TD 05W WILL TURN SHARPLY NORTHWESTWARD OVER EASTERN CHINA UNDER THE STEERING INFLUENCE OF A STR POSITIONED TO THE NORTH. RAPID WEAKENING AND DISSIPATION WILL OCCUR AS THE SYSTEM TRACKS INLAND. MODEL DISCUSSION: OVERALL, TRACK AND INTENSITY CONFIDENCE IS ASSESSED AT LOW DUE TO HIGH UNCERTAINTY IN THE SHORT-TERM TRACK AND EXTENDED PERIOD TRACK NEAR TAIWAN. DUE TO THE TRACK UNCERTAINTY, THERE IS HIGH UNCERTAINTY IN THE JTWC INTENSITY FORECAST, WHICH WILL BE IMPACTED BY THE PROXIMITY TO LAND MASSES AS THE SYSTEM THREADS THE NEEDLE THROUGH THE TAIWAN STRAIT. THE GFS DETERMINISTIC TRACKER, HOWEVER, HAS SHIFTED FURTHER WEST AND IS IN BETTER ALIGNMENT WITH THE AIDS ENVELOPE. RELIABLE INTENSITY GUIDANCE SUPPORTS THE JTWC INTENSITY FORECAST THROUGH TAU 48, WITH RAPID INTENSIFICATION GUIDANCE TRIGGERING. FORECAST CONFIDENCE: TRACK 0 - 72 HR: LOW TRACK 72-120 HR: LOW INTENSITY 0 - 72 HR: LOW INTENSITY 72-120 HR: LOW// NNNN