WDPN31 PGTW 030300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (JEBI) WARNING NR 13// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 09W (JEBI), LOCATED APPROXIMATELY 129 NM EASTWARD OF HANOI, VIETNAM, HAS TRACKED NORTHWESTWARD AT 11 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A TIGHTLY-WRAPPED LOW-LEVEL CIRCULATION CENTER WITH A BUILDING CENTRAL DENSE OVERCAST FEATURE. RADAR IMAGERY FROM GUANGXI, CHINA SHOWS THE LLCC IS CONTINUING TO TRACK ACROSS THE GULF OF TONKIN AND IS VERY CLOSE TO MAKING LANDFALL NEAR THE BORDER OF VIETNAM AND CHINA. THE INITIAL POSITION IS BASED ON THE ABOVE IMAGERY WITH HIGH CONFIDENCE. THE INITIAL INTENSITY OF 50 KNOTS IS BASED UPON AN AVERAGE OF DVORAK CURRENT INTENSITY ESTIMATES THAT RANGE FROM 55 TO 45 KNOTS. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS BEING AFFECTED BY LOW TO MODERATE (10-20 KNOTS) VERTICAL WIND SHEAR AND HAS EXCELLENT OUTFLOW, ESPECIALLY IN THE EQUATORWARD DIRECTION. TS 09W IS QUICKLY TRACKING NORTHWESTWARD ALONG THE PERIPHERY OF A MID TO DEEP-LAYERED SUBTROPICAL STEERING RIDGE THAT IS NORTHEAST OF THE SYSTEM. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 09W WILL CONTINUE TO TRACK NORTHWESTWARD ALONG THE PERIPHERY OF THE STR THROUGH THE FORECAST PERIOD, MAKING LANDFALL WITHIN THE NEXT SEVERAL HOURS. UPON LANDFALL, THE FRICTIONAL EFFECTS OF LAND WILL ERODE THE SYSTEM AND LEAD TO ITS DISSIPATION IN THE NEXT 36 HOURS. MODEL GUIDANCE IS IN TIGHT AGREEMENT THROUGH THE FORECAST PERIOD LENDING TO HIGH CONFIDENCE IN THE FORECAST, WHICH IS LAID CLOSE TO MULTI-MODEL CONSENSUS.// NNNN