WTPN31 PGTW 310300 1. TYPHOON 20W (PRAPIROON) WARNING NR 021 02 ACTIVE TROPICAL CYCLONES IN NORTHWESTPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE --- WARNING POSITION: 310000Z4 --- NEAR 33.2N8 123.8E4 MOVEMENT PAST SIX HOURS - 010 DEGREES AT 19 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT RADIUS OF 050 KT WINDS - 085 NM EAST SEMICIRCLE 055 NM ELSEWHERE RADIUS OF 035 KT WINDS - 160 NM EAST SEMICIRCLE OVER WATER 115 NM ELSEWHERE REPEAT POSIT: 33.2N8 123.8E4 --- FORECASTS: 12 HRS, VALID AT: 311200Z7 --- 36.5N4 125.3E1 MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT RADIUS OF 050 KT WINDS - 065 NM EAST SEMICIRCLE OVER WATER 050 NM ELSEWHERE RADIUS OF 035 KT WINDS - 135 NM EAST SEMICIRCLE OVER WATER 105 NM ELSEWHERE OVER WATER VECTOR TO 24 HR POSIT: 035 DEG/ 19 KTS --- 24 HRS, VALID AT: 010000Z1 --- 39.5N7 128.1E2 MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT RADIUS OF 050 KT WINDS - 040 NM SOUTHEAST SEMICIRCLE OVER WATER 030 NM ELSEWHERE OVER WATER RADIUS OF 035 KT WINDS - 120 NM SOUTHEAST SEMICIRCLE OVER WATER 080 NM ELSEWHERE OVER WATER VECTOR TO 36 HR POSIT: 050 DEG/ 15 KTS --- 36 HRS, VALID AT: 011200Z4 --- 41.5N0 131.1E6 MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT RADIUS OF 035 KT WINDS - 085 NM SOUTHEAST SEMICIRCLE 065 NM ELSEWHERE OVER WATER VECTOR TO 48 HR POSIT: 060 DEG/ 15 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 020000Z2 --- 43.0N7 134.6E4 MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER VECTOR TO 72 HR POSIT: 075 DEG/ 09 KTS --- 72 HRS, VALID AT: 030000Z3 --- 44.0N8 139.6E9 MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER --- REMARKS: 310300Z7 POSITION NEAR 34.0N7 124.2E9. TYPHOON (TY) 20W (PRAPIROON), LOCATED APPROXIMATELY 120 NM WEST OF CHEJU DO, HAS TRACKED NORTHWARD AT 19 KNOTS DURING THE PAST 6 HOURS. THE WARNING POSITION IS BASED ON 302330Z1 VISIBLE AND INFRARED SATELLITE IMAGERY. THE WARNING INTENSITY IS BASED ON SATELLITE CURRENT INTENSITY ESTIMATES OF 65 AND 77 KNOTS. THE 50 KNOT WIND RADII HAS BEEN INCREASED FROM THE PREVIOUS WARNING DUE TO A 310000Z4 SYNOPTIC REPORT OF 54 KNOTS FROM KOSAN-NI (47185), CHEJU DO. ANIMATED INFRARED SATELLITE IMAGERY SHOWS THAT THE SYSTEM REMAINS SYMMETRIC, HOWEVER CONVECTION HAS WEAKENED OVER THE PAST 6 HOURS. 200 MB ANALYSIS INDICATES TY 20W IS NORTH OF THE SUBTROPICAL RIDGE AND IS APPROACHING THE MID-LATITUDE SOUTHWESTERLIES. UW-CIMSS WIND SHEAR PRODUCTS INDICATE WEAK TO MODERATE VERTICAL WIND SHEAR OVER THE SYSTEM WITH MODERATE TO STRONG UPPER-LEVEL SOUTHWESTERLIES TO THE NORTH OF THE SYSTEM. TY 20W IS FORECAST TO TRACK INCREASINGLY NORTHEASTWARD THROUGH THE 36 HOUR PERIOD. THE SYSTEM IS THEN EXPECTED TO TURN INCREASINGLY EAST-NORTHEASTWARD AFTER THIS TIME THROUGH THE END OF THE FORECAST. TY 20W IS FORECAST TO SLOWLY WEAKEN THROUGH THE FORECAST PERIOD AS THE SYSTEM MOVES BENEATH THE MID- LATITUDE SOUTHWESTERLIES AHEAD OF A LONG WAVE TROUGH SITUATED OVER CHINA. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 310000Z4 IS 26 FEET. REFER TO WWPW30 RJTX FOR ADDITIONAL SEA HEIGHT INFORMATION. NEXT WARNINGS AT 310900Z3 (DTG 310751Z7), 311500Z0 (DTG 311351Z4), 312100Z7 (DTG 311951Z0) AND 010300Z4 (DTG 010151Z8). REFER TO TROPICAL STORM 21W (MARIA) WARNINGS (WTPN32 PGTW) FOR SIX-HOURLY UPDATES.// NNNN