WDPN32 PGTW 090900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 16W (PODUL) WARNING NR 010// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 21.6N 141.9E INITIAL INTENSITY: 50 KTS GEOGRAPHIC REFERENCE: 195 NM SOUTH OF IWO TO MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 09 KTS SIGNIFICANT WAVE HEIGHT: 20 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS LOW-LEVEL CLOUD BANDING PARTIALLY EXPOSED IN THE DRY, CLEAR AIR ALONG THE NORTHERN PERIPHERY OF TROPICAL STORM (TS) 16W. DEEP CONVECTION PERSISTS AGAINST STRONG VERTICAL WIND SHEAR OF 20-25KTS ASSOCIATED WITH ENHANCED UPPER-LEVEL EASTERLIES. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON THE AFOREMENTIONED LOW-LEVEL BANDING, HOWEVER THE LOW-LEVEL CIRCULATION CENTER (LLCC) IS OBSCURED AND UNIDENTIFIABLE ON MSI. THE INITIAL INTENSITY OF 50 KTS IS ASSESSED WITH LOW CONFIDENCE BASED ON THE AGENCY AND OBJECTIVE FIXES LISTED BELOW. INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE OVER EAST CHINA SEA AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T4.0 - 65 KTS RJTD: T2.5 - 35 KTS RCTP: T3.5 - 55 KTS KNES: T3.5 - 55 KTS CIMSS SATCON: 48 KTS AT 090353Z CIMSS ADT: 47 KTS AT 090540Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 20-25 KTS SST: 29-30 CELSIUS OUTFLOW: MODERATE EQUATORWARD ANALYSIS CONFIDENCE: INITIAL POSITION: MEDIUM INITIAL INTENSITY: LOW INITIAL WIND RADII: LOW 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TS 16W WILL TRACK WESTWARD FOR THE NEXT 48 HOURS UNDER THE STEERING INFLUENCE OF A SUBTROPICAL RIDGE CENTERED OVER THE EAST CHINA SEA. THE SYSTEM WILL CURVE NORTHWESTWARD FROM TAU 72-120 WHILE ROUNDING THE PERIPHERY OF THE ELONGATED SUBTROPICAL RIDGE. TS 16W WILL INTENSIFY TO A PEAK OF 65KTS BY TAU 48 WHILE IN FAVORABLE WARM SEA SURFACE TEMPERATURES, HIGH OCEAN HEAT CONTENT, AND MODERATE UPPER-LEVEL DIVERGENCE. THE RATE OF INTENSIFICATION WILL BE CAPPED BY STRONG 25-30KT VERTICAL WIND SHEAR DURING THE FIRST 36 HOURS. A DRY ENVIRONMENT WILL LINGER TO THE NORTH OF TS 16W ASSOCIATED WITH THE UPPER-LEVEL RIDGE THAT BUILDS OVER JAPAN. THE UPPER-LEVEL EASTERLIES WILL ENHANCE WITH THE BUILDING RIDGE AFTER TAU 48, INCREASING NORTHEASTERLY VERTICAL WIND SHEAR UNFAVORABLY ABOVE 40KTS FOR THE REMAINDER OF THE FORECAST. MID-LEVEL DRY AIR INTRUSION COUPLED WITH THE ELEVATED NORTHEASTERLY SHEAR WILL INITIATE WEAKENING FOR THE REMAINDER OF THE FORECAST PERIOD AS THE VERTICAL STRUCTURE OF TS 16W DEGRADES. TS 16W WILL WEAKEN TO 30KTS BY THE END OF THE FORECAST PERIOD AFTER MAKING LANDFALL ON MAINLAND CHINA. MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT THAT TS 16W WILL BE DRIVEN WESTWARD, AND THEN NORTHWESTWARD WHILE DRIVEN BY THE SUBTROPICAL RIDGE TO THE NORTH. THERE ARE SLIGHT VARIATIONS IN THE STRENGTH AND HOW FAR SOUTH THE RIDGE EXTENDS. THE CROSS-TRACK SPREAD AT TAU 72 IS 276NM. BY THE END OF THE FORECAST, THE SPREAD OPENS TO 490NM. NOTABLY, THE GFS SOLUTION LIES SOUTH OF CONSENSUS, BUT THE ECMWF AND GEFS SOLUTIONS ARE SIGNIFICANTLY CLOSER TO THE MULTI-MODEL CONSENSUS MEAN. THE JTWC TRACK FORECAST LIES CLOSELY TO THE NORTH OF THE CONSENSUS MEAN. THE JTWC INTENSITY GUIDANCE IS SIGNIFICANTLY SPREAD WITH PEAK INTENSITIES BETWEEN 55-75KTS. HAFS-A PEAKS AT APPROXIMATELY 75KTS AT TAU 36, WHILE COAMPS-TC (GFS-BASED) REACHES A PEAK OF 12 KTS AT TAU 12. THE TRACK VARIATIONS SIGNIFICANTLY AFFECT HOW STRONGLY THE SYSTEM WILL ERODE DUE TO DRY AIR AND STRONG SHEAR. IF THE SYSTEM TRACKS FARTHER NORTH, THE DRY AIR AND SHEAR WILL HAVE A STRONGER EFFECT THAN IF TS 16W TRACKS SOUTH. THE JTWC INTENSITY FORECAST LIES SLIGHTLY NORTH OF THE MULTI-MODEL INTENSITY CONSENSUS. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM TRACK 72-120 HR: LOW INTENSITY 0 - 72 HR: LOW INTENSITY 72-120 HR: LOW// NNNN