WDPN32 PGTW 041500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 05W (FIVE) WARNING NR 003// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 20.3N 118.0E INITIAL INTENSITY: 35 KTS GEOGRAPHIC REFERENCE: 347 NM SOUTHWEST OF TAIPEI, TAIWAN MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 04 KTS SIGNIFICANT WAVE HEIGHT: 14 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A CONSOLIDATING LOW-LEVEL CIRCULATION (LLC), WITH IMPROVED CONVECTIVE BANDING AND A DEVELOPING CENTRAL DENSE OVERCAST DRIVEN BY THE IMPROVING DUAL CHANNEL OUTFLOW. A 041051Z GMI 37GHZ COLOR COMPOSITE MICROWAVE IMAGE REVEALS IMPROVED CONVECTIVE BANDING OVER THE SOUTHERN SEMICIRCLE, WRAPPING INTO THE EASTERN QUADRANT, WITH A DEFINED LOW-LEVEL CIRCULATION CENTER. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE GMI IMAGE AND A 041244Z ASCAT-B BULLSEYE IMAGE. THE INITIAL INTENSITY OF 35 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE ASCAT-B IMAGE, WHICH SHOWS 30-35 KNOT WINDS, AND THE PGTW, KNES AND DEMS SUBJECTIVE DVORAK ESTIMATES. INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK CURRENT STEERING MECHANISM: COMPETING STEERING ENVIRONMENT WITH A LOW-LEVEL SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTH AND A NEAR-EQUATORIAL RIDGE BUILDING TO THE SOUTHEAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T2.5 - 35 KTS RJTD: T1.5 - 25 KTS KNES: T2.5 - 35 KTS DEMS: T2.5 - 35 KTS CIMSS ADT: 35 KTS AT 041130Z CIMSS AIDT: 36 KTS AT 041130Z CIMSS D-MINT: 32 KTS AT 041048Z CIMSS D-PRINT: 34 KTS AT 041150Z 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: LOW 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TROPICAL STORM (TS) 05W IS FORECAST TO MEANDER SLOWLY NORTHWESTWARD WITHIN THE COMPETING STEERING ENVIRONMENT THROUGH TAU 12. AFTER TAU 12, THE SYSTEM WILL INTENSIFY QUICKLY AND TRACK NORTHWARD TO NORTH-NORTHEASTWARD ALONG THE BUILDING STR ENTRENCHED TO THE EAST. TS 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, TS 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