WTPS31 PGTW 310900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 15P (ANA) WARNING NR 006// RMKS/ 1. TROPICAL CYCLONE 15P (ANA) WARNING NR 006 03 ACTIVE TROPICAL CYCLONES IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 310600Z --- NEAR 18.8S 178.2E MOVEMENT PAST SIX HOURS - 180 DEGREES AT 07 KTS POSITION ACCURATE TO WITHIN 040 NM POSITION BASED ON CENTER LOCATED BY A COMBINATION OF SATELLITE AND SYNOPTIC DATA PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 025 NM NORTHEAST QUADRANT 025 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 090 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 165 NM NORTHEAST QUADRANT 120 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 180 NM NORTHWEST QUADRANT REPEAT POSIT: 18.8S 178.2E --- FORECASTS: 12 HRS, VALID AT: 311800Z --- 20.1S 178.5E MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 210 NM NORTHEAST QUADRANT 160 NM SOUTHEAST QUADRANT 120 NM SOUTHWEST QUADRANT 120 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 160 DEG/ 06 KTS --- 24 HRS, VALID AT: 010600Z --- 21.3S 179.0E MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 230 NM NORTHEAST QUADRANT 170 NM SOUTHEAST QUADRANT 140 NM SOUTHWEST QUADRANT 110 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 145 DEG/ 07 KTS --- 36 HRS, VALID AT: 011800Z --- 22.5S 179.9E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 070 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 210 NM NORTHEAST QUADRANT 160 NM SOUTHEAST QUADRANT 120 NM SOUTHWEST QUADRANT 120 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 145 DEG/ 11 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 020600Z --- 24.3S 178.6W MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 170 NM NORTHEAST QUADRANT 160 NM SOUTHEAST QUADRANT 110 NM SOUTHWEST QUADRANT 110 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 135 DEG/ 14 KTS --- 72 HRS, VALID AT: 030600Z --- 28.3S 174.0W 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 - 130 NM NORTHEAST QUADRANT 110 NM SOUTHEAST QUADRANT 080 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 130 DEG/ 16 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 040600Z --- 32.4S 168.5W MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER --- REMARKS: 310900Z POSITION NEAR 19.1S 178.3E. 31JAN21. TROPICAL CYCLONE (TC) 15P (ANA), LOCATED APPROXIMATELY 44 NM SOUTH-SOUTHWEST OF SUVA, FIJI, HAS TRACKED SOUTHWARD AT 07 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A CENTRAL DENSE OVERCAST FEATURE OBSCURING THE LOW- LEVEL CIRCULATION CENTER (LLCC) WITH A BANDING FEATURE OVER THE EASTERN SEMICIRCLE. A 310502Z SSMIS 37GHZ MICROWAVE IMAGE INDICATES A DEFINED LLCC POSITIONED ON THE NORTHERN EDGE OF THE DEEP CONVECTION, WHICH SUPPORTS THE INITIAL POSITION WITH GOOD CONFIDENCE. SURFACE OBSERVATIONS AT NAUSORI (91683) INDICATE NORTHERLY WINDS AT 21 KNOTS (10-MINUTE AVERAGE), WHICH ALSO SUPPORTS THE INITIAL POSITION. THE INITIAL INTENSITY REMAINS ASSESSED AT 65 KNOTS BASED ON THE PGTW DVORAK ESTIMATE OF T4.0 (65 KNOTS) AND A 310600Z ADT ESTIMATE OF 3.8 (ABOUT 61 KNOTS). UPPER-LEVEL ANALYSIS INDICATES A GENERALLY FAVORABLE ENVIRONMENT WITH MODERATE VERTICAL WIND SHEAR (VWS) OFFSET BY ROBUST POLEWARD OUTFLOW. ADDITIONALLY, SST VALUES (29-30C) REMAIN CONDUCIVE. TC 15P IS FORECAST TO ACCELERATE SOUTH-SOUTHEASTWARD TO SOUTHEASTWARD THROUGH TAU 96 ALONG THE SOUTHWESTERN PERIPHERY OF A SUBTROPICAL RIDGE WITH INCREASING VWS (30-35 KNOTS). ADDITIONALLY, SST VALUES ARE EXPECTED TO DECREASE TO 24-22C AFTER TAU 48, WHICH WILL LEAD TO MORE RAPID WEAKENING AND DISSIPATION BY TAU 96. NUMERICAL MODEL GUIDANCE REMAINS IN GOOD AGREEMENT LENDING HIGH CONFIDENCE TO THE JTWC FORECAST TRACK WITH A 160-180NM SPREAD IN MODEL SOLUTIONS AFTER TAU 48. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 310600Z IS 21 FEET. NEXT WARNINGS AT 311500Z, 312100Z, 010300Z AND 010900Z. REFER TO TROPICAL CYCLONE 16P (SIXTEEN) WARNINGS (WTPS32 PGTW) FOR SIX-HOURLY UPDATES. REFER TO TROPICAL CYCLONE 17P (LUCAS) WARNINGS (WTPS33 PGTW) FOR SIX- HOURLY UPDATES.// NNNN