WTPS31 PGTW 311500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 15P (ANA) WARNING NR 007// RMKS/ 1. TROPICAL CYCLONE 15P (ANA) WARNING NR 007 03 ACTIVE TROPICAL CYCLONES IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 311200Z --- NEAR 19.6S 178.6E MOVEMENT PAST SIX HOURS - 160 DEGREES AT 08 KTS POSITION ACCURATE TO WITHIN 030 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 055 NM NORTHEAST QUADRANT 055 NM SOUTHEAST QUADRANT 045 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 150 NM NORTHEAST QUADRANT 135 NM SOUTHEAST QUADRANT 155 NM SOUTHWEST QUADRANT 160 NM NORTHWEST QUADRANT REPEAT POSIT: 19.6S 178.6E --- FORECASTS: 12 HRS, VALID AT: 010000Z --- 20.8S 179.0E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 055 NM NORTHEAST QUADRANT 055 NM SOUTHEAST QUADRANT 045 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 150 NM NORTHEAST QUADRANT 135 NM SOUTHEAST QUADRANT 155 NM SOUTHWEST QUADRANT 160 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 150 DEG/ 07 KTS --- 24 HRS, VALID AT: 011200Z --- 22.0S 179.7E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 150 NM NORTHEAST QUADRANT 135 NM SOUTHEAST QUADRANT 155 NM SOUTHWEST QUADRANT 160 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 140 DEG/ 10 KTS --- 36 HRS, VALID AT: 020000Z --- 23.5S 179.0W MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 190 NM NORTHEAST QUADRANT 150 NM SOUTHEAST QUADRANT 130 NM SOUTHWEST QUADRANT 110 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 140 DEG/ 13 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 021200Z --- 25.4S 177.2W 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 - 170 NM NORTHEAST QUADRANT 150 NM SOUTHEAST QUADRANT 110 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 135 DEG/ 15 KTS --- 72 HRS, VALID AT: 031200Z --- 29.4S 172.4W MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER --- REMARKS: 311500Z POSITION NEAR 19.9S 178.7E. 31JAN21. TROPICAL CYCLONE (TC) 15P (ANA), LOCATED APPROXIMATELY 91 NM SOUTH OF SUVA, FIJI, HAS TRACKED SOUTH-SOUTHEASTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A BROAD AREA OF FLARING DEEP CONVECTION ORIENTED EAST-WEST. A 310922Z MHS 89GHZ MICROWAVE IMAGE REVEALS AN EXPOSED, DEFINED LOW-LEVEL CIRCULATION CENTER POSITIONED ON THE NORTHWEST EDGE OF A CURVED DEEP CONVECTIVE BAND WITH SHALLOW BANDING OVER THE WESTERN SEMICIRCLE. UPPER-LEVEL ANALYSIS INDICATES A MARGINALLY- FAVORABLE ENVIRONMENT WITH MODERATE TO STRONG (20-30 KNOTS) VERTICAL WIND SHEAR (VWS) OFFSET BY ROBUST POLEWARD OUTFLOW. A 311017Z ASCAT- C IMAGE DEPICTS A DEFINED CIRCULATION, WHICH SUPPORTS THE INITIAL POSITION WITH GOOD CONFIDENCE, WITH 45-50 KNOT WINDS OVER THE SOUTHERN AND EASTERN SEMICIRCLES. BASED ON THE WEAKENED STRUCTURE EVIDENT IN MICROWAVE IMAGERY AND ASCAT-C DATA, THE INITIAL INTENSITY IS ASSESSED AT 55 KNOTS, HEDGED BELOW A PGTW DVORAK FINAL-T ESTIMATE OF T4.0. TC 15P IS FORECAST TO ACCELERATE SOUTH-SOUTHEASTWARD TO SOUTHEASTWARD THROUGH TAU 72 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 72. NUMERICAL MODEL GUIDANCE REMAINS IN GOOD AGREEMENT LENDING HIGH CONFIDENCE TO THE JTWC FORECAST TRACK WITH A 160NM SPREAD IN MODEL SOLUTIONS AT TAU 72. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 311200Z IS 21 FEET. NEXT WARNINGS AT 312100Z, 010300Z, 010900Z AND 011500Z. 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