WDPN32 PGTW 200300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 15W (PULASAN) WARNING NR 014// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 32.0N 120.3E INITIAL INTENSITY: 30 KTS GEOGRAPHIC REFERENCE: 78 NM NORTHWEST OF SHANGHAI, CHINA MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 14 KTS SIGNIFICANT WAVE HEIGHT: OVER LAND SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL DEPRESSION 15W (PULASAN) AS A NEARLY COMPLETELY EXPOSED, WELL-DEFINED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH CONVECTION BEGINNING TO DISSIPATE DUE TO ITS TIME OVER LAND. THE STRONGEST WINDS CONTINUE TO BE DISPLACED TO THE EAST OVER WATER IN THE EAST CHINA SEA. ENVIRONMENTAL ANALYSIS INDICATES THAT 15W IS IN A MARGINALLY UNFAVORABLE ENVIRONMENT CHARACTERIZED BY MODERATE EASTWARD OUTFLOW ALOFT AND LOW (5-10 KTS) VERTICAL WIND SHEAR OFFSET BY TERRAIN INTERACTION ALONG EASTERN CHINA. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE ANIMATED MSI SHOWING THE DEFINED LLCC. THE INITIAL INTENSITY OF 30 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED MAINLY ON THE OBJECTIVE CIMSS INTENSITY ESTIMATES AND OBS FROM THE EAST CHINA SEA AREA. INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND RADII). CURRENT STEERING MECHANISM: WEAK STEERING ENVIRONMENT AS THE SUBTROPICAL RIDGE (STR) TO THE EAST REORIENTS. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: NO CURRENT ESTIMATE RJTD: T1.5 - 25 KTS CIMSS DMINT: 31 KTS AT 192215Z CIMSS DPRINT: 33 KTS AT 200000Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY UNFAVORABLE VWS: 5-10 KTS SST: OVER LAND OUTFLOW: MODERATE EASTWARD OTHER FACTORS: TERRAIN INTERACTION ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: NOT APPLICABLE 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: 15W IS FORECAST TO BEGIN TRACKING NORTH-NORTHEASTWARD OVER THE NEXT 12 HOURS AS AN EXTENSION OF THE RIDGE TO ITS EAST BREAKS DOWN. AFTER TAU 12, ONCE THE RIDGE HAS FULLY REORIENTED, 15W IS EXPECTED TO QUICKLY TRAVERSE EAST-NORTHEASTWARD WHERE IT WILL MAKE A SECOND LANDFALL ALONG THE SOUTHWESTERN COAST OF SOUTH KOREA AT AROUND TAU 30. AFTERWARDS, 15W WILL CONTINUE ITS FAST-PACED TRACK INTO THE SEA OF JAPAN AS IT PASSES JUST NORTH OF BUSAN. EXTRATROPICAL TRANSITION IS FORECAST TO BEGIN AROUND TAU 36 WITH COMPLETION BY TAU 48 AS THE JET GETS PUSHED SOUTHWARD DUE TO AN INCOMING TROUGH. THE INTENSITY FORECAST CALLS FOR A MILD INTENSIFICATION TREND TO A PEAK OF 40 KTS AT TAU 24 ONCE THE VORTEX HAS AROUND 12 HOURS OF BEING BACK OVER WATER. 40 KTS IS FORECAST TO BE MAINTAINED THROUGH TAU 48 AS THE SYSTEM INTERACTS WITH THE BAROCLINIC ZONE AND TRANSITIONS INTO AN EXTRATROPICAL LOW. WARM SEA SURFACE TEMPERATURES WILL AID INTENSIFICATION, HOWEVER THE STRONG VERTICAL WIND SHEAR IN THE AREA WILL HINDER ANY FURTHER DEVELOPMENT. MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT WITH A MERE 38 NM CROSS TRACK SPREAD AT TAU 36 AS IT APPROACHES BUSAN. THIS LENDS HIGH CONFIDENCE TO THE JTWC TRACK FORECAST. INTENSITY GUIDANCE IS ALSO IN GOOD AGREEMENT WITH MODELS SUGGESTING A PEAK INTENSITY OF 40-45 KTS AT TAU 36. GFS CALLS FOR A SLIGHTLY HIGHER PEAK OF 45 KTS DUE TO A BIT FASTER TRACK SPEED. THE VORTEX IS PLACED BACK OVER WATER AT THAT TIME RATHER THAN NORTH OF BUSAN. THE JTWC INTENSITY FORECAST IS PLACED SLIGHTLY BELOW CONSENSUS AT TAU 36 IN RESPONSE TO THE VERY HIGH SHEAR AND TERRAIN INTERACTION WITH SOUTH KOREA DURING THAT TIME. THE SLIGHT VARIATION BETWEEN TRACK SPEEDS CAUSES THE JTWC INTENSITY FORECAST TO BE PLACED WITH MEDIUM CONFIDENCE DUE TO DIFFERENT AMOUNTS OF LAND INTERACTION WITH SOUTH KOREA. FORECAST CONFIDENCE: TRACK 0 - 72 HR: HIGH INTENSITY 0 - 72 HR: MEDIUM// NNNN