SUBJ: TROPICAL CYCLONE WARNING WTPN31 PGTW 181500 1. TROPICAL DEPRESSION 01W WARNING NR 003 01 ACTIVE TROPICAL CYCLONE IN NORTHWESTPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE --- WARNING POSITION: 181200Z2 --- NEAR 11.3N5 123.6E2 MOVEMENT PAST SIX HOURS - 275 DEGREES AT 11 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY A COMBINATION OF SATELLITE AND SYNOPTIC DATA PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT REPEAT POSIT: 11.3N5 123.6E2 --- FORECASTS: 12 HRS, VALID AT: 190000Z0 --- 11.4N6 122.5E0 MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT VECTOR TO 24 HR POSIT: 275 DEG/ 06 KTS --- 24 HRS, VALID AT: 191200Z3 --- 11.5N7 121.3E7 MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT VECTOR TO 36 HR POSIT: 300 DEG/ 05 KTS --- 36 HRS, VALID AT: 200000Z2 --- 12.0N3 120.4E7 MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT VECTOR TO 48 HR POSIT: 300 DEG/ 06 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 201200Z5 --- 12.6N9 119.4E5 MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT VECTOR TO 72 HR POSIT: 320 DEG/ 07 KTS --- 72 HRS, VALID AT: 211200Z6 --- 14.9N4 117.5E4 MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT RADIUS OF 035 KT WINDS - 050 NM NORTHEAST SEMICIRCLE 040 NM ELSEWHERE --- REMARKS: 181500Z5 POSITION NEAR 11.3N5 123.3E9. TROPICAL DEPRESSION (TD) 01W, LOCATED OVER THE CENTRAL PHILIPPINE ISLANDS, HAS TRACKED WESTWARD AT 11 KNOTS DURING THE PAST 6 HOURS. THE WARNING POSITION IS BASED ON 181130Z4 ENHANCED INFRARED SATELLITE IMAGERY AND SYNOPTIC REPORTS. THE WARNING INTENSITY IS BASED ON SATELLITE CURRENT INTENSITY ESTIMATES OF 25 KNOTS. ENHANCED INFRARED ANIMATION DEPICTS THAT THE CONVECTION HAS WEAKENED AND HAS DECREASED IN COVERAGE CONSIDERABLY DURING THE PAST 6 HOURS. ANIMATION AND A 180420Z5 TROPICAL RAINFALL MEASURING MISSION (TRMM 37GHZ) PASS ALSO REVEAL THAT A DEFINITIVE LOW-LEVEL CIRCULATION CENTER HAS BECOME VERY DIFFICULT TO LOCATE. LOW-MID LEVEL HIGH CENTERED OVER THE NORTHERN MARIANA ISLANDS, WITH ASSOCIATED RIDGE EXTENDING WESTWARD ACROSS LUZON, IS EXPECTED TO WEAKEN LATE IN THE PERIOD. THEREFORE, TD 01W IS FORECAST TO TRACK WEST-NORTHWESTWARD BEFORE TURNING MORE NORTHWESTWARD LATE IN THE FORECAST. LITTLE CHANGE IN INTENSITY IS FORECAST THROUGH THE NEXT 24 HOURS. AFTERWARD, TD 01W SHOULD GRADUALLY INTENSIFY AS IT TRACKS TOWARD THE UPPER RIDGE AXIS. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 181200Z2 IS 20 FEET. REFER TO WWPW31 RJTX FOR ADDITIONAL SEA HEIGHT INFORMATION. NEXT WARNINGS AT 182100Z2 (DTG 181952Z6), 190300Z3 (DTG 190152Z8), 190900Z9 (DTG 190752Z4) AND 191500Z6 (DTG 191352Z1).// NNNN