WDPN32 PGTW 140900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (CHANTHU) WARNING NR 033// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 30.7N 124.3E INITIAL INTENSITY: 45 KTS GEOGRAPHIC REFERENCE: 310 NM WEST-SOUTHWEST OF SASEBO, JAPAN MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 07 KTS SIGNIFICANT WAVE HEIGHT: 20 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC), WITH THE REMAINING ASSOCIATED CONVECTION REMAINING TO THE NORTH AND WEST. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE LLCC SEEN IN MSI. THE INITIAL INTENSITY OF 45 KNOTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON A 140230Z METOP-B ASCAT PASS WHICH SHOWS PEAK WIND BARBS OF 40 KNOTS. THE OVERALL MARGINALLY UNFAVORABLE CONDITIONS, ARE DUE TO THE LOW OCEAN HEAT CONTENT AND MEDIUM TO STRONG VERTICAL WIND SHEAR, WHICH ARE OFFSET BY THE STRONG UPPER LEVEL DIVERGENCE DISPLACED TO THE EAST OF THE LLCC. INITIAL WIND RADII BASIS: SCATTEROMETER DATA CURRENT STEERING MECHANISM: COL BETWEEN SUBTROPICAL RIDGE (STR) TO THE NORTHWEST AND STR TO THE SOUTHEAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T3.5 - 55 KTS RJTD: T3.5 - 55 KTS RCTP: T3.5 - 55 KTS CIMSS ADT: 32 KTS AT 140510Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY UNFAVORABLE VWS: 5-10 KTS SST: 28-29 CELSIUS OUTFLOW: MODERATE POLEWARD AND EQUATORWARD ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH 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: TS CHANTU IS EXPECTED TO REMAIN QUASI-STATIONARY (QS) OVER THE NEXT TWO DAYS IN THE COL. AFTERWARD, THE STR TO THE NORTHWEST WILL WEAKEN, ALLOWING THE SECONDARY STR TO THE SOUTHEAST TO ASSUME STEERING AND DRIVE THE SYSTEM NORTHEASTWARD THROUGH THE SEA OF JAPAN (SOJ), CROSSING NORTHERN HONSHU NEAR MISAWA AND EXITING INTO THE PACIFIC OCEAN SHORTLY AFTER TAU 96. THE MARGINALLY UNFAVORABLE CONDITIONS, EXACERBATED BY FURTHER COOLING OF THE SSTS AS THE QS SYSTEM GENERATES UPWELLING OF DEEP COLD WATER, WILL PROMOTE STEADY WEAKENING DOWN TO 35 KNOTS BY TAU 48. AFTERWARD, THE NORTHEASTWARD TRACK INTO HIGHER VWS AND COLDER SSTS OF THE SOJ WILL FURTHER WEAKEN IT TO 30KTS BY TAU 96 AS IT BECOMES FULLY EXTRATROPICAL. MODEL DISCUSSION: NUMERICAL MODELS ARE IN OVERALL GOOD AGREEMENT. HOWEVER, GIVEN THE UNCERTAINTY IN THE STORM MOTION AND DURATION IN THE COL AREA, THERE IS LOW CONFIDENCE IN THE JTWC TRACK FORECAST THAT IS LAID CLOSE TO THE MODEL CONSENSUS. FORECAST CONFIDENCE: TRACK 0 - 72 HR: LOW TRACK 72-120 HR: MEDIUM INTENSITY 0 - 72 HR: LOW INTENSITY 72-120 HR: MEDIUM// NNNN