WDPN31 PGTW 191500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (IN-FA) WARNING NR 014// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 24.0N 131.5E INITIAL INTENSITY: 55 KTS GEOGRAPHIC REFERENCE: 251 NM SOUTHEAST OF KADENA AB MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 03 KTS SIGNIFICANT WAVE HEIGHT: 24 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS TIGHTLY- CURVED BANDING WRAPPING INTO A WELL-DEFINED LOW-LEVEL CIRCULATION CENTER (LLCC), WHICH SUPPORTS THE INITIAL POSITION AND RECENT TRACK MOTION WITH HIGH CONFIDENCE. THE 190000Z 500MB ANALYSIS CHART INDICATES THAT THE SUBTROPICAL RIDGE (STR) BUILT TO THE NORTH OF THE SYSTEM AS PREDICTED BY THE NUMERICAL MODELS, AND THE 191200Z NAZE SOUNDING (47909) INDICATES FURTHER STRENGTHENING OF THE ASSOCIATED DEEP EASTERLY FLOW FROM THE SURFACE TO 300MB. AS A CONSEQUENCE, TS 09W IS TRACKING SLOWLY WEST-NORTHWESTWARD. THE INITIAL INTENSITY IS ASSESSED AT 55 KNOTS BASED ON THE KNES DVORAK ESTIMATE. A 191301Z ASCAT-B IMAGE INDICATES NUMEROUS 45-50 KNOT WINDS OVER THE NORTHERN SEMICIRCLE. ENVIRONMENTAL ANALYSIS INDICATES FAVORABLE CONDITIONS WITH ROBUST POLEWARD AND EQUATORWARD OUTFLOW ENHANCED BY THE TUTT TO THE EAST, LOW VERTICAL WIND SHEAR (VWS) AND WARM SST VALUES. INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK CURRENT STEERING MECHANISM: STR CENTERED OVER HONSHU EXTENDING SOUTHWARD OVER THE NORTHERN AND NORTHWESTERN PERIPHERY OF THE SYSTEM. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T3.0 - 45 KTS RJTD: T3.0 - 45 KTS RCTP: T3.0 - 45 KTS KNES: T3.5 - 55 KTS CIMSS ADT: 45 KTS AT 191140Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 10-15 KTS SST: 29-30 CELSIUS OUTFLOW: STRONG POLEWARD AND EQUATORWARD ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: HIGH 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 09W IS EXPECTED TO TRACK WEST-NORTHWESTWARD TO WESTWARD ALONG THE SOUTHERN PERIPHERY OF THE STR THROUGH TAU 72. AFTER TAU 72, TS 09W SHOULD TURN WEST-NORTHWESTWARD AS IT TRACKS ALONG THE SOUTHWESTERN PERIPHERY OF THE STR. TS 09W SHOULD STEADILY INTENSIFY THROUGH TAU 72 TO A PEAK INTENSITY OF 95 KNOTS. AFTER TAU 72, TS 09W WILL WEAKEN SLIGHTLY AS IT PASSES TO THE NORTH OF TAIWAN AND APPROACHES THE COAST OF CHINA. MODEL DISCUSSION: BASED ON 500MB ANALYSES AND UPPER AIR SOUNDINGS FROM NAZE, THERE IS INCREASING CONFIDENCE IN THE TRACK FORECAST THROUGH TAU 72 WITH MEDIUM CONFIDENCE; AT TAU 36 THERE IS A 60NM SPREAD IN NUMERICAL MODEL GUIDANCE AND AT TAU 72 THERE IS A 180NM SPREAD IN SOLUTIONS. AFTER TAU 72, MODEL GUIDANCE DIVERGES WITH A LARGE SPREAD AND LOW CONFIDENCE. THERE IS MEDIUM CONFIDENCE IN THE JTWC INTENSITY FORECAST THROUGH THE FORECAST PERIOD. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM TRACK 72-120 HR: LOW INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN