SUBJ: TROPICAL CYCLONE WARNING WTPN31 PGTW 181500 1. TROPICAL STORM 26W (SHANSHAN) WARNING NR 005 01 ACTIVE TROPICAL CYCLONES IN NORTHWESTPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE --- WARNING POSITION: 181200Z2 --- NEAR 16.3N0 171.0E9 MOVEMENT PAST SIX HOURS - 315 DEGREES AT 07 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT RADIUS OF 035 KT WINDS - 055 NM NORTHEAST SEMICIRCLE 045 NM ELSEWHERE REPEAT POSIT: 16.3N0 171.0E9 --- FORECASTS: 12 HRS, VALID AT: 190000Z0 --- 17.4N2 170.2E0 MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT RADIUS OF 050 KT WINDS - 025 NM RADIUS OF 035 KT WINDS - 070 NM NORTHEAST SEMICIRCLE 050 NM ELSEWHERE VECTOR TO 24 HR POSIT: 325 DEG/ 07 KTS --- 24 HRS, VALID AT: 191200Z3 --- 18.5N4 169.4E0 MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT RADIUS OF 050 KT WINDS - 035 NM 020 NM ELSEWHERE RADIUS OF 035 KT WINDS - 080 NM NORTHEAST SEMICIRCLE 060 NM ELSEWHERE VECTOR TO 36 HR POSIT: 330 DEG/ 07 KTS --- 36 HRS, VALID AT: 200000Z2 --- 19.7N7 168.6E1 MAX SUSTAINED WINDS - 075 KT, GUSTS 090 KT RADIUS OF 050 KT WINDS - 055 NM NORTHEAST SEMICIRCLE 040 NM ELSEWHERE RADIUS OF 035 KT WINDS - 120 NM NORTHEAST SEMICIRCLE 105 NM ELSEWHERE VECTOR TO 48 HR POSIT: 325 DEG/ 07 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 201200Z5 --- 20.8N0 167.8E2 MAX SUSTAINED WINDS - 080 KT, GUSTS 100 KT RADIUS OF 050 KT WINDS - 055 NM NORTHEAST SEMICIRCLE 045 NM ELSEWHERE RADIUS OF 035 KT WINDS - 130 NM NORTHEAST SEMICIRCLE 115 NM ELSEWHERE OVER WATER VECTOR TO 72 HR POSIT: 335 DEG/ 08 KTS --- 72 HRS, VALID AT: 211200Z6 --- 23.8N3 166.3E6 MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT RADIUS OF 050 KT WINDS - 070 NM NORTHEAST SEMICIRCLE 050 NM ELSEWHERE RADIUS OF 035 KT WINDS - 140 NM NORTHEAST SEMICIRCLE 125 NM ELSEWHERE --- REMARKS: 181500Z5 POSITION NEAR 16.6N3 170.8E6. TROPICAL STORM (TS) 26W (SHANSHAN), LOCATED APPROXIMATELY 300 NM SOUTHEAST OF WAKE ISLAND, HAS TRACKED NORTHWESTWARD AT 07 KNOTS DURING THE PAST 6 HOURS. THE WARNING POSITION IS BASED ON 181130Z4 INFRARED SATELLITE IMAGERY. THE WARNING INTENSITY IS BASED ON SATELLITE CURRENT INTENSITY ESTIMATES OF 55 KNOTS. ANIMATED INFRARED IMAGERY DEPICTS IMPROVING ORGANIZATION OVER THE PAST 6 HOURS WITH AN INCREASE IN SPIRAL BANDING WRAPPING IN TOWARD THE CENTER OF THE CIRCULATION. A 180929Z9 SPECIAL SENSOR MICROWAVE IMAGER PASS DEPICTS STRONGEST CONVECTION SOUTH THROUGH WEST OF THE SYSTEM CENTER. ANIMATED WATER VAPOR IMAGERY DEPICTS GOOD OUTFLOW ALOFT WITH A TROPICAL UPPER TROPOSPHERIC LOW NORTHWEST OF TS 26W, WHICH IS ENHANCING THE OUTFLOW. TS 26W SHOULD TRACK GENERALLY NORTHWESTWARD WITHIN A WEAKNESS IN THE RIDGE THROUGH THE PERIOD. THE 180000Z9 ANALYSIS REVEALS THE SUBTROPICAL RIDGE EXTENDING WESTWARD FROM A POINT NORTH OF THE HAWAIIAN ISLANDS TO THE EAST COAST OF JAPAN. TS 26W IS FORECAST TO INTENSIFY AT A CLIMATOLOGICAL RATE THROUGH THE PERIOD UNDER AN IMPROVING ENVIRONMENT. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 181200Z2 IS 12 FEET. REFER TO WWPW31 RJTX FOR ADDITIONAL SEA HEIGHT INFORMATION. NEXT WARNINGS AT 182100Z2 (DTG 181951Z5), 190300Z3 (DTG 190151Z7), 190900Z9 (DTG 190751Z3) AND 191500Z6 (DTG 191351Z0).//