WDPN32 PGTW 151500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (CHANTHU) WARNING NR 038// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 30.1N 125.5E INITIAL INTENSITY: 45 KTS GEOGRAPHIC REFERENCE: 260 NM SOUTHWEST OF SASEBO, JAPAN MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 06 KTS SIGNIFICANT WAVE HEIGHT: 18 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THE SYSTEM HAS MAINTAINED ITS CENTRAL CONVECTION, OBCURING THE LOW LEVEL CIRCULATION CENTER (LLCC). THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON A 151147Z METOP-A ASCAT PASS. THE INITIAL INTENSITY IS ASSESSED WITH GOOD CONFIDENCE BASED ON THE AFOREMENTIONED ASCAT PASS, SATCON, AS WELL AS AGENCY AND AUTOMATED DVORAK ESTIMATES. ANALYSIS INDICATES A MARGINALLY FAVORABLE ENVIRONMENT WITH MODERATE OUTFLOW AND LOW VWS. THE SYSTEM HAS RETRACED ITS PATH OVER THE LAST SIX HOURS, WHICH HAS LIKELY RESTRAINED ITS DEVELOPMENT DUE TO THE COOLER UPWELLED WATERS UNDER ITS CENTRAL CONVECTION. INITIAL WIND RADII BASIS: SCATTEROMETER DATA CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE EXTENSION TO THE NORTHEAST AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T3.0 - 45 KTS RJTD: T2.5 - 35 KTS KNES: T2.5 - 35 KTS CIMSS SATCON: 49 KTS AT 1210Z CIMSS ADT: 49 KTS AT 151140Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 0-5 KTS SST: 28-29 CELSIUS OUTFLOW: MODERATE POLEWARD AND EQUATORWARD OTHER FACTORS: LOW OCEAN HEAT CONTENT DUE TO RETRACE OF PATH ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: HIGH INITIAL WIND RADII: HIGH 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TS 19W HAS FINALLY BEGUN ITS RECURVE AROUND THE SUBTROPICAL RIDGE, LOCATED TO ITS NORTHEAST. THE MARGINALLY FAVORABLE ENVIRONMENT OVER THE NEXT 24 HOURS WILL LIKELY ALLOW FOR SLIGHT INTENSIFICATION TO 50 KNOTS AS IT APPROACHES THE TSUSHIMA STRAIT, UNDER SUSTAINED UPPER LEVEL OUTFLOW, LOW SHEAR AND WARM SEA SURFACE TEMPERATURES (28-29 DEGREES CELSIUS). AS THE SYSTEM TRACKS OVER JAPAN, AFTER PASSING IWAKUNI AROUND TAU 48, INCREASING VWS AND LAND INTERACTION WILL WEAKEN IT WHILE IT BEGINS EXTRATROPICAL TRANSITION. EXTRATROPICAL TRANSITION IS EXPECTED TO COMPLETE NO LATER THAN TAU 72. MODEL DISCUSSION: NUMERICAL MODELS HAVE STAYED CONSISTENT SINCE THE PREVIOUS FORECAST, WITH LANDFALL EXPECTED SHORTLY BEFORE TAU 48. AFUM HAS MAINTAINED AS THE OUTLIER WITH A TRACK OVER THE SEA OF JAPAN, WHEREAS THE REMAINING CONSENSUS MEMBERS EXPECT TS 19W TO TRACK ACROSS JAPAN NEAR KYOTO. GIVEN THE UNCERTAINTY IN THE STORM MOTION IN THE COL, THERE IS ONLY MEDIUM CONFIDENCE IN THE JTWC TRACK FORECAST DESPITE TIGHT MODEL GROUPING. INTENSITY FORECAST CONFIDENCE IS MEDIUM DUE TO SUSTAINED COMPETING ENVIRONMENTAL FACTORS AND RECURVE TIMING. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM INTENSITY 0 - 72 HR: MEDIUM// NNNN