WDPN33 PGTW 130300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 24W (KOMPASU) WARNING NR 012// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 19.1N 113.1E INITIAL INTENSITY: 55 KTS GEOGRAPHIC REFERENCE: 202 NM SOUTH-SOUTHWEST OF HONG KONG MOVEMENT PAST 6 HOURS: WESTWARD AT 13 KTS SIGNIFICANT WAVE HEIGHT: 21 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TROPICAL STORM KOMPASU CONTINUES TO FIGHT AGAINST PERSISTENT MODERATE EASTERLY SHEAR. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) REVEALS THAT THE LARGE AREA OF DEEP CONVECTION THAT WAS EARLIER BLOOMING NEAR THE CENTER HAS WEAKENED AND SHEARED OFF TO THE WEST, LEAVING BEHIND A MUCH SMALLER AREA OF WEAKER CONVECTIVE ACTIVITY NEAR OR JUST WEST OF THE ASSESSED LOW LEVEL CIRCULATION CENTER (LLCC). A 122251Z SSMIS 91GHZ MICROWAVE IMAGE CAUGHT THE BEGINNING OF THE DEVELOPMENT OF THIS AREA OF CORE CONVECTION, SHOWING A STRONG BAND OF HEAVY CONVECTIVE ACTIVITY TO THE SOUTH WRAPPING UP ALONG THE EASTERN SIDE OF THE LLCC, BUT NOT YET COMPLETELY SURROUNDING THE CORE. THE FIRST HINTS OF THE CENTER OF ROTATION ARE STARTING TO BECOME VISIBLE AT FAR RANGE OF CMA RADAR COVERAGE, AND JMA HAS BEEN CONDUCTING RADAR FIXES, WHICH COMBINED WITH THE AGENCY FIX POSITIONS, LENT HIGH CONFIDENCE TO THE INITIAL POSITION. THE INITIAL INTENSITY REMAINS ASSESSED AT 55 KTS WITH HIGH CONFIDENCE, WITH ALL AGENCIES AGREEING ON A T3.5 INTENSITY. THERE HAS BEEN NO SIGNIFICANT CHANGE IN THE ENVIRONMENT OVER THE PAST SIX HOURS, WITH PERSISTENT EASTERLY SHEAR STILL PUSHING BACK AGAINST MODERATE TO STRONG EQUATORWARD OUTFLOW AND VERY WARM SSTS. INITIAL WIND RADII BASIS: PERSISTENCE, SHIP AND LAND OBSERVATIONS. CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) ENTRENCHED OVER CENTRAL CHINA. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T3.5 - 55 KTS RJTD: T3.5 - 55 KTS KNES: T3.5 - 55 KTS CIMSS ADT: 47 KTS AT 122340Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 20-25 KTS SST: 29-30 CELSIUS OUTFLOW: MODERATE POLEWARD 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: TROPICAL STORM KOMPASU CONTINUES TO TRACK FAIRLY RAPIDLY WESTWARD ALONG THE SOUTHERN PERIPHERY OF A DEEP STR TO THE NORTH. SPEED MADE GOOD OVER THE PAST SIX HOURS HAS SLOWED SLIGHTLY, BUT IS STILL UP AROUND 15 KNOTS OR SO. THE SYSTEM WILL MAINTAIN A WESTWARD TRACK THROUGH THE FORECAST PERIOD, AND IS EXPECTED TO MAKE LANDFALL ALONG THE EASTERN COAST OF HAINAN WITHIN THE NEXT 10 HOURS. THE QUICK TRANSLATION SPEED ACROSS HAINAN ISLAND WILL LIMIT THE IMPACT OF THE TERRAIN, AND KOMPASU WILL REEMERGE IN THE GULF OF TONKIN AS A 40 KNOT TROPICAL STORM. HOWEVER, BY THIS TIME, SHEAR WILL HAVE INCREASED ONCE AGAIN, WHICH COMBINED WITH WEAKLY CONVERGENT OUTFLOW ALOFT, WILL PRECLUDE INTENSIFICATION. THE SYSTEM WILL MAKE A SECOND LANDFALL IN NORTH VIETNAM NEAR TAU 36 AND CONTINUE TRACKING INLAND INTO NORTHERN LAOS, WHERE IT IS FORECAST TO DISSIPATE NO LATER THAN TAU 72. MODEL DISCUSSION: TRACK GUIDANCE IS IN VERY GOOD AGREEMENT THROUGH THE LANDFALL IN VIETNAM, WHERE AFTER THE TRACKERS SPREAD OUT AS THEY LOSE THE WEAKENING VORTEX. THE JTWC REMAINS CONSISTENT WITH THE PREVIOUS FORECAST AND NEAR THE CONSENSUS MEAN TRACKER WITH HIGH CONFIDENCE. INTENSITY GUIDANCE IS LIKEWISE IN GOOD AGREEMENT THROUGH THE FORECAST PERIOD, LENDING HIGH CONFIDENCE TO THE JTWC FORECAST. FORECAST CONFIDENCE: TRACK 0 - 72 HR: HIGH INTENSITY 0 - 72 HR: HIGH// NNNN