WTPS51 PGTW 050900 WARNING ATCG MIL 23P SWP 210305070755 2021030506 23P NIRAN 018 01 120 24 SATL 060 T000 178S 1568E 115 R064 065 NE QD 045 SE QD 030 SW QD 060 NW QD R050 115 NE QD 085 SE QD 060 SW QD 115 NW QD R034 205 NE QD 155 SE QD 115 SW QD 200 NW QD T012 200S 1612E 120 R064 040 NE QD 030 SE QD 030 SW QD 040 NW QD R050 090 NE QD 050 SE QD 060 SW QD 070 NW QD R034 240 NE QD 170 SE QD 140 SW QD 190 NW QD T024 224S 1659E 110 R064 030 NE QD 020 SE QD 030 SW QD 030 NW QD R050 080 NE QD 050 SE QD 060 SW QD 070 NW QD R034 230 NE QD 160 SE QD 140 SW QD 160 NW QD T036 247S 1709E 075 R064 020 NE QD 010 SE QD 020 SW QD 020 NW QD R050 060 NE QD 040 SE QD 050 SW QD 070 NW QD R034 200 NE QD 150 SE QD 120 SW QD 140 NW QD T048 264S 1761E 060 R050 030 NE QD 020 SE QD 030 SW QD 050 NW QD R034 160 NE QD 110 SE QD 100 SW QD 140 NW QD T072 287S 1739W 050 R050 060 NE QD 040 SE QD 020 SW QD 060 NW QD R034 090 NE QD 090 SE QD 080 SW QD 130 NW QD AMP 036HR BECOMING EXTRATROPICAL 048HR BECOMING EXTRATROPICAL 072HR EXTRATROPICAL SUBJ: TROPICAL CYCLONE 23P (NIRAN) WARNING NR 018 1. TROPICAL CYCLONE 23P (NIRAN) WARNING NR 018 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 050600Z --- NEAR 17.8S 156.8E MOVEMENT PAST SIX HOURS - 120 DEGREES AT 24 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON EYE FIXED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 115 KT, GUSTS 140 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 065 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 115 NM NORTHEAST QUADRANT 085 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 115 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 205 NM NORTHEAST QUADRANT 155 NM SOUTHEAST QUADRANT 115 NM SOUTHWEST QUADRANT 200 NM NORTHWEST QUADRANT REPEAT POSIT: 17.8S 156.8E --- FORECASTS: 12 HRS, VALID AT: 051800Z --- 20.0S 161.2E MAX SUSTAINED WINDS - 120 KT, GUSTS 145 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 090 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 240 NM NORTHEAST QUADRANT 170 NM SOUTHEAST QUADRANT 140 NM SOUTHWEST QUADRANT 190 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 120 DEG/ 25 KTS --- 24 HRS, VALID AT: 060600Z --- 22.4S 165.9E MAX SUSTAINED WINDS - 110 KT, GUSTS 135 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 080 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 230 NM NORTHEAST QUADRANT 160 NM SOUTHEAST QUADRANT 140 NM SOUTHWEST QUADRANT 160 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 120 DEG/ 26 KTS --- 36 HRS, VALID AT: 061800Z --- 24.7S 170.9E MAX SUSTAINED WINDS - 075 KT, GUSTS 090 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING SUBTROPICAL RADIUS OF 064 KT WINDS - 020 NM NORTHEAST QUADRANT 010 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 200 NM NORTHEAST QUADRANT 150 NM SOUTHEAST QUADRANT 120 NM SOUTHWEST QUADRANT 140 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 110 DEG/ 25 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 070600Z --- 26.4S 176.1E MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING SUBTROPICAL RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 160 NM NORTHEAST QUADRANT 110 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 140 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 105 DEG/ 23 KTS --- 72 HRS, VALID AT: 080600Z --- 28.7S 173.9W MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY SUBTROPICAL RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 090 NM NORTHEAST QUADRANT 090 NM SOUTHEAST QUADRANT 080 NM SOUTHWEST QUADRANT 130 NM NORTHWEST QUADRANT --- REMARKS: 050900Z POSITION NEAR 18.4S 157.9E. 05MAR21. TROPICAL CYCLONE 23P (NIRAN), LOCATED APPROXIMATELY 584 NM WEST-NORTHWEST OF NOUMEA, NEW CALEDONIA, HAS TRACKED EAST- SOUTHEASTWARD AT 24 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THE EMERGENCE OF A VERY WELL DEFINED 12NM EYE BY THE 0600Z HOUR. A 050557Z SSMIS 91H MICROWAVE IMAGE SHOWED HOWEVER THAT THE DEEP CONVECTION DOES NOT EXTEND ALL THE WAY AROUND THE SYSTEM, WITH A DISTINCT BREAK IN THE EYEWALL ON THE SOUTHEASTERN SIDE, INDICATIVE OF INCREASING EASTERLY WIND SHEAR. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON BOTH THE SSMIS MICROWAVE IMAGE AND THE 10NM EYE IN THE INFRARED IMAGERY. THE INITIAL INTENSITY IS ASSESSED AT 115 KNOTS, HEDGED SLIGHTLY LOWER THAN A PGTW DVORAK CURRENT INTENSITY ESTIMATE OF T6.5 (127 KTS) AND CLOSELY ALIGNED TO A 114 KNOT WIND SPEED MEASUREMENT FROM A 050227Z AMSR2 PASS. TC 23P IS RAPIDLY MOVING SOUTHEASTWARD ALONG THE SOUTHWESTERN PERIPHERY OF A COMBINED NEAR EQUATORIAL AND SUBTROPICAL RIDGE COMPLEX CENTERED TO THE NORTHEAST. THE ENVIRONMENT REMAINS FAVORABLE FOR THE MOMENT, WITH MODERATE (20-25 KT) VWS BEING OFFSET BY VERY STRONG POLEWARD OUTFLOW AND WARM (29C) SSTS. THE SYSTEM IS FORECAST TO CONTINUE TRACKING SOUTHEASTWARD THROUGH TAU 48 ALONG THE TIGHT GRADIENT BETWEEN THE RIDGE COMPLEX TO THE NORTHEAST AND AN APPROACHING MAJOR SHORTWAVE TROUGH TO THE WEST. BY THE END OF THE FORECAST, THE SYSTEM WILL MOVE SLIGHTLY MORE EASTWARD AS IT COMES UNDER THE STEERING INFLUENCE OF A DYNAMIC LOW TO MID-LEVEL ANTICYCLONE TO THE SOUTH. IN THE NEAR-TERM, GOOD ENVIRONMENTAL CONDITIONS WILL SUPPORT ADDITIONAL INTENSIFICATION TO A PEAK OF 120 KNOTS BY TAU 12. THEREAFTER, ENVIRONMENTAL CONDITIONS BEGIN TO RAPIDLY DETERIORATE AS THE VWS INCREASES TO AN EXTENT THAT THE OUTFLOW CANNOT OVERCOME IT AND THE CORE BECOMES DISRUPTED. AFTER TAU 48, VWS WEAKENS A BIT BUT DRY AIR ENTRAINMENT AND COOL SSTS AT OR BELOW 26C WILL SERVE TO FURTHER WEAKEN THE SYSTEM AS IT BEGINS SUBTROPICAL TRANSITION. THE TRANSITION TO A STORM FORCE SUBTROPICAL SYSTEM WILL BE COMPLETE NO LATER THAN, AND POSSIBLY EARLIER, THAN TAU 72. NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU 24 BUT CROSS AND ALONG-TRACK UNCERTAINTY INCREASES SIGNIFICANTLY THEREAFTER. THE JTWC FORECAST LIES NEAR THE CONSENSUS MEAN THROUGH TAU 24, THEN NEAR THE ECMWF TRACK THROUGH THE REMAINDER OF THE FORECAST PERIOD. OVERALL THERE IS HIGH CONFIDENCE IN THE FIRST 24 HOURS OF THE FORECAST, AND LOW CONFIDENCE THEREAFTER. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 050600Z IS 40 FEET. NEXT WARNINGS AT 051500Z, 052100Z, 060300Z AND 060900Z.// 2321022706 154S1489E 20 2321022712 159S1489E 20 2321022718 164S1488E 25 2321022800 166S1487E 25 2321022806 169S1485E 30 2321022812 171S1482E 30 2321022818 173S1477E 30 2321030100 172S1472E 35 2321030106 167S1468E 35 2321030112 161S1469E 40 2321030118 155S1473E 45 2321030200 150S1477E 50 2321030200 150S1477E 50 2321030206 149S1479E 50 2321030206 149S1479E 50 2321030212 148S1481E 55 2321030212 148S1481E 55 2321030218 149S1482E 55 2321030218 149S1482E 55 2321030300 149S1480E 65 2321030300 149S1480E 65 2321030300 149S1480E 65 2321030306 149S1479E 70 2321030306 149S1479E 70 2321030306 149S1479E 70 2321030312 148S1479E 70 2321030312 148S1479E 70 2321030312 148S1479E 70 2321030318 150S1482E 80 2321030318 150S1482E 80 2321030318 150S1482E 80 2321030400 152S1486E 85 2321030400 152S1486E 85 2321030400 152S1486E 85 2321030406 155S1495E 90 2321030406 155S1495E 90 2321030406 155S1495E 90 2321030412 154S1505E 90 2321030412 154S1505E 90 2321030412 154S1505E 90 2321030418 159S1525E 95 2321030418 159S1525E 95 2321030418 159S1525E 95 2321030500 167S1546E 110 2321030500 167S1546E 110 2321030500 167S1546E 110 2321030506 178S1568E 115 2321030506 178S1568E 115 2321030506 178S1568E 115 NNNN