WTPS31 PGTW 202300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 17P (SEVENTEEN) WARNING NR 001// REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/200351ZFEB2020// AMPN/REF A IS A TROPICAL CYCLONE FORMATION ALERT.// RMKS/ 1. TROPICAL CYCLONE 17P (SEVENTEEN) WARNING NR 001 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 201800Z --- NEAR 14.3S 171.5W MOVEMENT PAST SIX HOURS - 125 DEGREES AT 11 KTS POSITION ACCURATE TO WITHIN 020 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 015 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT REPEAT POSIT: 14.3S 171.5W --- FORECASTS: 12 HRS, VALID AT: 210600Z --- 16.0S 170.4W MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 015 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 165 DEG/ 08 KTS --- 24 HRS, VALID AT: 211800Z --- 17.6S 170.0W MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 190 DEG/ 05 KTS --- 36 HRS, VALID AT: 220600Z --- 18.6S 170.2W MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 010 NM SOUTHWEST QUADRANT 010 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 235 DEG/ 06 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 221800Z --- 19.3S 171.2W MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER --- REMARKS: 202100Z POSITION NEAR 14.7S 171.2W. 20FEB20. TROPICAL CYCLONE (TC) 17P (SEVENTEEN), LOCATED APPROXIMATELY 47 NM WEST OF PAGO PAGO, HAS TRACKED SOUTHEASTWARD AT 11 KNOTS OVER THE PAST SIX HOURS. THIS IS A LATE CYCLE 201800Z WARNING BEING ISSUED AT 202300Z. ANIMATED MULTISPECTRAL IMAGERY INDICATES A COMPACT CIRCULATION WITHIN THE SPCZ HAS RAPIDLY CONSOLIDATED OVER THE PAST SIX HOURS. SCATTEROMETRY DATA AS THE SYSTEM APPROACHED WESTERN SAMOA INDICATED 30 KNOTS, AND OBSERVATIONS AT MAOTA AND FALEOLO AIRPORTS SUPPORTED THIS ESTIMATE. ADDITIONALLY, DVORAK ESTIMATES AT 18Z RANGED FROM T1.5 TO T2.0 (25-30 KNOTS). HOWEVER, A 201937Z OBSERVATION FROM PAGO PAGO FOUND 40 KNOTS SUSTAINED WITH GUSTS TO 65 KNOTS. THE DVORAK ESTIMATE IS LIKELY UNDER-REPRESENTING THE ACTUAL PEAK INTENSITY DUE TO THE COMPACT NATURE OF THE CONVECTIVE CORE. THEREFORE, THE INTENSITY IS NOW ASSESSED AT 45 KNOTS. TC 17P IS TRACKING SOUTHEASTWARD ALONG A PERSISTENT TROUGH AND IS IN A FAVORABLE ENVIRONMENT WITH WARM (27-28 CELSIUS) SEA SURFACE TEMPERATURES, LOW (10-15KTS) VERTICAL WIND SHEAR (VWS) AND ESTABLISHED POLEWARD OUTFLOW. THE SYSTEM IS EXPECTED TO BEGIN A GENERALLY SOUTH-SOUTHEASTWARD TRACK AT TAU 12, BECOMING SOUTHWARD AFTER TAU 24. AS THE TRACK BEGINS TO TURN SOUTH-SOUTHWESTWARD AFTER TAU 24, TC 17P WILL BEGIN TO DISSIPATE OVER WATER DUE TO INCREASING VWS AND COOLER SST, WEAKENING TO 35 KTS BY TAU 36. INCREASINGLY UNFAVORABLE CONDITIONS WILL LEAD TO FULL DISSIPATION OVER WATER BY TAU 48. NUMERICAL MODEL SOLUTIONS ARE IN POOR AGREEMENT WITH A 184 NM SPREAD AT TAU 12 INCREASING TO 295 NM AT TAU 48. ADDITIONALLY, SOME NUMERICAL MODEL SOLUTIONS DEPICT 17P INTERACTING WITH 96P AFTER TAU 48. THE COMBINATION OF POTENTIAL SYSTEM INTERACTION AND HIGH DEGREE OF SPREAD YIELDS LOW CONFIDENCE TO THE OVERALL JTWC FORECAST TRACK. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 202300Z IS 15 FEET. NEXT WARNINGS AT 210300Z, 210900Z, 211500Z AND 212100Z. 2. THIS CANCELS AND SUPERSEDES REF A (WTPS21 PGTW 190400).// NNNN