WTPS51 PGTW 100900 WARNING ATCG MIL 20P SWP 210210065655 2021021006 20P TWENTY 002 01 170 16 SATL 040 T000 267S 1774W 040 R034 165 NE QD 135 SE QD 080 SW QD 070 NW QD T012 299S 1764W 040 R034 170 NE QD 160 SE QD 070 SW QD 050 NW QD T024 331S 1747W 035 R034 170 NE QD 160 SE QD 070 SW QD 050 NW QD T036 361S 1723W 030 AMP 012HR BECOMING EXTRATROPICAL 024HR BECOMING EXTRATROPICAL 036HR EXTRATROPICAL SUBJ: TROPICAL CYCLONE 20P (TWENTY) WARNING NR 002 1. TROPICAL CYCLONE 20P (TWENTY) WARNING NR 002 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 100600Z --- NEAR 26.7S 177.4W MOVEMENT PAST SIX HOURS - 170 DEGREES AT 16 KTS POSITION ACCURATE TO WITHIN 040 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 165 NM NORTHEAST QUADRANT 135 NM SOUTHEAST QUADRANT 080 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT REPEAT POSIT: 26.7S 177.4W --- FORECASTS: 12 HRS, VALID AT: 101800Z --- 29.9S 176.4W MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING EXTRATROPICAL RADIUS OF 034 KT WINDS - 170 NM NORTHEAST QUADRANT 160 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 155 DEG/ 18 KTS --- 24 HRS, VALID AT: 110600Z --- 33.1S 174.7W MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING EXTRATROPICAL RADIUS OF 034 KT WINDS - 170 NM NORTHEAST QUADRANT 160 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 145 DEG/ 18 KTS --- 36 HRS, VALID AT: 111800Z --- 36.1S 172.3W MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY EXTRATROPICAL --- REMARKS: 100900Z POSITION NEAR 27.5S 177.1W. 10FEB21. TROPICAL CYCLONE 20P (TWENTY), LOCATED APPROXIMATELY 566 NM SOUTH-SOUTHEAST OF SUVA, FIJI, HAS TRACKED SOUTHWARD AT 16 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A WELL DEFINED AND PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC), WITH MODERATE CONVECTION DISPLACED TO THE SOUTHEAST. THE OVERALL DEPICTION IN THE MSI IS INCREASINGLY EXTRATROPICAL, WITH THE COMMA-SHAPED CONVECTIVE ENVELOPE NOW POLEWARD AND EASTWARD OF THE LLCC. A TIMELY 100600Z GMI 36GHZ MICROWAVE IMAGE WITH A WELL-DEFINED LOW EMISSIVITY REGION AND LOW LEVEL CONVECTIVE BANDING FEATURES LENT HIGH CONFIDENCE TO THE INITIAL POSITION. THE INITIAL INTENSITY IS LOWERED TO 40 KNOTS WITH FAIR CONFIDENCE BASED ON A BLEND OF A DVORAK CURRENT INTENSITY ESTIMATE OF T2.5 (35 KTS) FROM PGTW, AND AN ADT ESTIMATE OF T3.0 (45 KTS), AS WELL AS AN EXTRAPOLATION OF 100116Z AMSR2 WINDSPEED ANALYSIS WHICH SHOWED 40-50KT WINDS CONFINED TO THE SOUTHEAST QUADRANT, WITH 35-40KT WINDS ELSEWHERE. TC 20P IS MOVING RAPIDLY SOUTHWARD ALONG TIGHT GRADIENT BETWEEN THE STR TO THE EAST AND DEEP MID-LATITUDE TROUGH TO THE WEST. THE OVERALL ENVIRONMENT IS NOT SUPPORTIVE OF TROPICAL CYCLONE DEVELOPMENT, WITH COOL (24-26C) SSTS, VERY HIGH (>30KT) VWS AND ROBUST POLEWARD OUTFLOW. THERMAL CROSS-SECTION AND THICKNESS ANALYSIS REVEALS THE SYSTEM HAS BOTH TROPICAL AND EXTRATROPICAL FEATURES AT WARNING TIME. AS THE SYSTEM CONTINUES MOVING SOUTH-SOUTHEASTWARD IT WILL ENCOUTER INCREASINGLY UNFAVORABLE CONDITIONS, AND BECOME EMBEDDED IN THE BAROCLINIC ZONE UNDER THE UPPER-LEVEL JET, TRANSITIONING TO A FULLY EXTRATROPICAL SYSTEM AT OR BEFORE TAU 36. NUMERICAL MODEL GUIDANCE IS IN VERY GOOD AGREEMENT THROUGH THE FORECAST PERIOD LENDING HIGH CONFIDENCE TO THE JTWC FORECAST TRACK, WHICH REMAINS CONSISTENT WITH THE PREVIOUS WARNING, NEAR THE MULTI-MODEL CONSENSUS MEAN. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 100600Z IS 18 FEET. NEXT WARNINGS AT 101500Z, 102100Z, 110300Z AND 110900Z.// 2021020618 133S1774E 15 2021020700 136S1775E 15 2021020706 139S1779E 15 2021020712 142S1783E 15 2021020718 147S1787E 15 2021020800 151S1791E 20 2021020806 159S1795E 20 2021020812 173S1799E 25 2021020818 185S1800W 30 2021020900 193S1798W 30 2021020906 201S1793W 30 2021020912 218S1786W 30 2021020918 235S1779W 35 2021021000 251S1777W 45 2021021006 267S1774W 40 NNNN