WDPN31 PGTW 122100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 01W (WUTIP) WARNING NR 010// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 17.7N 109.0E INITIAL INTENSITY: 50 KTS GEOGRAPHIC REFERENCE: 265 NM SOUTHEAST OF HANOI, VIETNAM MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 04 KTS SIGNIFICANT WAVE HEIGHT: 21 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A DEEP-LAYER CONVECTIVE CANOPY FULLY OBSCURING THE LOW-LEVEL CIRCULATION CENTER (LLCC) OF TROPICAL STORM (TS) 01W (WUTIP). ENVIRONMENTAL ANALYSIS REVEALS THE NORTHEASTERLY VERTICAL WIND SHEAR (VWS) HAVING A MARGINALLY REDUCED IMPACT ON THE STRUCTURE OF THE SYSTEM OVER THE LAST FEW HOURS. PERSISTENT CONVECTION IS A BIT MORE SYMMETRICAL, WITH STRONG EQUATORWARD OUTFLOW CHANNEL. CLOUD TOPS HAVE WARMED UP TO -82 C SINCE THE PEAK OF -92 C YESTERDAY, HOWEVER AS THE LLCC IS NOW TRANSITING AROUND THE ISLAND OF HAINAN, THE SYSTEM IS IN FAVORABLE ENVIRONMENT FOR INTENSIFICATION. AVAILABILITY OF WARM (29-30 C) SEA SURFACE TEMPERATURES (SST) AROUND THE ISLAND, COMBINED WITH AVAILABLE DEEP-LAYER ATMOSPHERIC MOISTURE CONTENT WILL ALSO AID IN ANY POTENTIAL INTENSIFICATION, HOWEVER WIND FIELD INTERACTION WITH THE TERRAIN WILL HAVE A DETRIMENTAL EFFECT. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON ANIMATED EIR IMAGERY AIDED BY THE RADAR LOOP. THE INITIAL INTENSITY OF 50 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE GOOD AGREEMENT AMONG THE AGENCY DVORAK FIXES, OBJECTIVE ESTIMATES LISTED BELOW, AS WELL AS A 121430Z METOP-C ASCAT PASS WIND MEASUREMENTS. INITIAL WIND RADII BASIS: A 121430Z METOP-C ASCAT PASS CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE NORTHEAST AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T3.5 - 55 KTS RJTD: T2.5 - 35 KTS RCTP: T3.0 - 45 KTS KNES: T3.5 - 55 KTS CIMSS SATCON: 44 KTS AT 121710Z CIMSS ADT: 47 KTS AT 121800Z CIMSS AIDT: 40 KTS AT 121800Z CIMSS D-PRINT: 51 KTS AT 121800Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 15-20 KTS SST: 29-30 CELSIUS OUTFLOW: STRONG EQUATORWARD ANALYSIS CONFIDENCE: INITIAL POSITION: MEDIUM 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 01W IS FORECAST TO ROUND THE AXIS OF A STR TO THE NORTHEAST WITHIN THE NEXT 12-24 HOURS. AT THE SAME TIME, THE LLCC IS EXPECTED TO TRAVEL OUTSIDE THE WESTERN PERIPHERY OF HAINAN ISLAND, PRIOR TO MAKING A NORTHEASTWARD TURN, EVENTUALLY LEADING TO LANDFALL NEAR OR JUST WEST OF THE LEIZHOU PENINSULA. AS THE SYSTEM TRANSITS OVER THE WARM WATERS OF THE GULF OF TONKIN, IT IS EXPECTED TO SLIGHTLY INTENSIFY, DESPITE POTENTIAL LAND INTERACTION, AND REACH 55 KTS BETWEEN TAUS 12 AND 24. AS SOON AS THE SYSTEM MAKES LANDFALL OVER MAINLAND CHINA, IT IS FORECAST TO BEGIN DISSIPATING AND TO COMPLETE THE PROCESS BY TAU 72. MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN GOOD AGREEMENT THROUGHOUT THE FORECAST, AS WITNESSED BY A 30 NM CROSS-TRACK SPREAD MAXIMUM PRIOR TO LANDFALL, OPENING UP TO 75 NM BY TAU 72. THE ONLY OUTLIER IS CURRENTLY GFS, WHICH PREDICTS A SLIGHTLY MORE WESTERN TRACK SOON AFTER LANDFALL, HOWEVER THE DISTANCE FROM THE CONSENSUS IS JUST 30 NM. INTENSITY GUIDANCE IS IN FAIR AGREEMENT WITH ALL MODELS PREDICTING INTENSIFICATION THROUGHOUT THE INITIAL 12-24 HOURS, FOLLOWED BY A STEADY WEAKENING TREND. NOTABLE OUTLIERS ARE HAFS AND NAVGEM-DRIVEN COAMPS-TC, WITH BOTH INDICATING PEAK INTENSITY AROUND 70-75 KTS, HOWEVER CONSIDERING THE LIKELY TIMELINE OF THE LANDFALL, THOSE ARE ASSESSED TO BE UNLIKELY SCENARIOS. JTWC TRACK AND INTENSITY FORECASTS ARE BOTH LAID IN CLOSE PROXIMITY TO THE MULTI-MODEL CONSENSUS GUIDANCE WITH HIGH AND MEDIUM CONFIDENCE ACCORDINGLY. FORECAST CONFIDENCE: TRACK 0 - 72 HR: HIGH INTENSITY 0 - 72 HR: MEDIUM// NNNN