WTPN31 PGTW 280900 1. TROPICAL STORM 20W (PRAPIROON) WARNING NR 010 02 ACTIVE TROPICAL CYCLONES IN NORTHWESTPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE --- WARNING POSITION: 280600Z6 --- NEAR 22.6N0 126.2E1 MOVEMENT PAST SIX HOURS - 250 DEGREES AT 12 KTS POSITION ACCURATE TO WITHIN 120 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT REPEAT POSIT: 22.6N0 126.2E1 --- FORECASTS: 12 HRS, VALID AT: 281800Z9 --- 23.3N8 124.4E1 MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT RADIUS OF 035 KT WINDS - 190 NM NORTHEAST SEMICIRCLE 140 NM ELSEWHERE VECTOR TO 24 HR POSIT: 320 DEG/ 09 KTS --- 24 HRS, VALID AT: 290600Z7 --- 24.6N2 123.1E7 MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT RADIUS OF 035 KT WINDS - 195 NM NORTHEAST SEMICIRCLE 145 NM ELSEWHERE OVER WATER VECTOR TO 36 HR POSIT: 305 DEG/ 10 KTS --- 36 HRS, VALID AT: 291800Z0 --- 25.8N5 121.2E6 MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT RADIUS OF 050 KT WINDS - 040 NM RADIUS OF 035 KT WINDS - 195 NM NORTHEAST SEMICIRCLE OVER WATER 145 NM ELSEWHERE OVER WATER VECTOR TO 48 HR POSIT: 305 DEG/ 10 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 300600Z9 --- 26.9N7 119.3E4 MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND RADIUS OF 050 KT WINDS - 050 NM OVER WATER RADIUS OF 035 KT WINDS - 195 NM NORTHEAST SEMICIRCLE OVER WATER 145 NM ELSEWHERE OVER WATER VECTOR TO 72 HR POSIT: 335 DEG/ 10 KTS --- 72 HRS, VALID AT: 310600Z0 --- 30.6N9 117.3E2 MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND --- REMARKS: 280900Z9 POSITION NEAR 22.8N2 125.8E6. TROPICAL STORM (TS) 20W (PRAPIROON), LOCATED APPROXIMATELY 225 NM SOUTHWEST OF OKINAWA HAS TRACKED WEST-SOUTHWESTWARD AT 12 KNOTS OVER THE PAST 6 HOURS. THE WARNING POSITION IS BASED ON 281130Z5 VISIBLE AND INFRARED SATELLITE IMAGERY. THE WARNING INTENSITY IS BASED ON SATELLITE CURRENT INTENSITY ESTIMATES OF 30 AND 35 KNOTS AND SYNOPTIC REPORTS OF 25 KNOTS. ANIMATED INFRARED AND VISIBLE SATELLITE IMAGERY SHOWS A BROAD CIRCULATION WITH SMALLER MULTIPLE LOW LEVEL CIRCULATIONS ORBITING THE CENTER OF THE BROADER CIRCULATION. IMAGERY ALSO SHOWS A BAND OF DEEP CONVECTION WRAPPING FROM THE WEST TO THE SOUTH OF THE CIRCULATION CENTER. UW-CIMSS ANALYSIS INDICATES WEAK NORTHEASTERLY VERTICAL WIND SHEAR OVER THE AREA, WHILE THE 200 MB ANALYSIS PLACES THE UPPER LEVEL RIDGE AXIS JUST TO THE NORTHWEST OF THE SYSTEM. TS 20W IS FORECAST TO TRACK NORTHWESTWARD UNDER THE STEERING INFLUENCE OF THE SUBTROPICAL RIDGE TO THE NORTHEAST. TS 20W IS FORECAST TO INTENSIFY AT A LESS THAN CLIMATOLOGICAL RATE UNDER A FAIR UPPER LEVEL ENVIRONMENT, BEFORE MAKING LANDFALL NEAR FU CHOU, CHINA MAXIMUM SIGNIFICANT WAVE HEIGHT AT 280600Z6 IS 20 FEET. REFER TO WWPW30 RJTX FOR ADDITIONAL SEA HEIGHT INFORMATION. NEXT WARNINGS AT 281500Z6 (DTG 281351Z0), 282100Z3 (DTG 281951Z6), 290300Z4 (DTG 290151Z8) AND 290900Z0 (DTG 290751Z4). REFER TO TROPICAL DEPRESSION 21W (NONAME) WARNINGS (WTPN32 PGTW) FOR SIX-HOURLY UPDATES.// BT #0001 NNNN