WTPS31 PGTW 060300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 23P (NIRAN) WARNING NR 021// RMKS/ 1. TROPICAL CYCLONE 23P (NIRAN) WARNING NR 021 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 060000Z --- NEAR 21.2S 163.7E MOVEMENT PAST SIX HOURS - 120 DEGREES AT 25 KTS POSITION ACCURATE TO WITHIN 045 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 110 KT, GUSTS 135 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 050 NM NORTHEAST QUADRANT 055 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 090 NM NORTHEAST QUADRANT 100 NM SOUTHEAST QUADRANT 090 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 150 NM NORTHEAST QUADRANT 140 NM SOUTHEAST QUADRANT 130 NM SOUTHWEST QUADRANT 140 NM NORTHWEST QUADRANT REPEAT POSIT: 21.2S 163.7E --- FORECASTS: 12 HRS, VALID AT: 061200Z --- 23.5S 168.7E MAX SUSTAINED WINDS - 085 KT, GUSTS 105 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 040 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 080 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 180 NM NORTHEAST QUADRANT 150 NM SOUTHEAST QUADRANT 130 NM SOUTHWEST QUADRANT 150 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 120 DEG/ 28 KTS --- 24 HRS, VALID AT: 070000Z --- 26.2S 174.2E MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING EXTRATROPICAL RADIUS OF 064 KT WINDS - 020 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 010 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 180 NM NORTHEAST QUADRANT 120 NM SOUTHEAST QUADRANT 110 NM SOUTHWEST QUADRANT 150 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 110 DEG/ 25 KTS --- 36 HRS, VALID AT: 071200Z --- 27.9S 179.5E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING EXTRATROPICAL RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 140 NM NORTHEAST QUADRANT 100 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 140 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 105 DEG/ 23 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 080000Z --- 28.9S 175.3W MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY EXTRATROPICAL RADIUS OF 034 KT WINDS - 090 NM NORTHEAST QUADRANT 080 NM SOUTHEAST QUADRANT 080 NM SOUTHWEST QUADRANT 110 NM NORTHWEST QUADRANT --- REMARKS: 060300Z POSITION NEAR 21.8S 165.0E. 06MAR21. TROPICAL CYCLONE 23P (NIRAN), LOCATED APPROXIMATELY 144 NM WEST-NORTHWEST OF NOUMEA, NEW CALEDONIA, HAS TRACKED EAST- SOUTHEASTWARD AT 25 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) REVEALS THE EYE HAS FILLED AND CONVECTION IS BECOMING MORE RAGGED AND FRONTAL IN NATURE AS NIRAN ACCELERATES TO THE SOUTHEAST. A 052005Z SSMIS PASS REVEALS THE DEGRADATION OF CORE STRUCTURE. THE INITIAL POSITION WAS BASED ON TRACKING OF THE FILLING EYE IN MSI AS IT APPROACHED NEW CALEDONIA. THE INTENSITY WAS ASSESSED AT 110 KNOTS, WHICH IS CLOSE TO CIMSS ADT ESTIMATES AND BELOW AGENCY CURRENT INTENSITY ESTIMATES GIVEN THE RAPID WEAKENING OBSERVED. ALTHOUGH POLEWARD OUTFLOW REMAINS ROBUST, VERTICAL WIND SHEAR IS NOW 30 KNOTS AND EXPECTED TO INCREASE. ADDITIONALLY, NIRAN IS TRACKING THROUGH A SHARP GRADIENT OF DECLINING SEA SURFACE TEMPERATURE VALUES. TC 23P IS TRACKING RAPIDLY EAST-SOUTHEASTWARD WITHIN THE TIGHT UPPER-LEVEL GRADIENT BETWEEN THE DEEP-LAYER RIDGE TO THE NORTH AND A MAJOR SHORTWAVE TROUGH TO THE SOUTH. THE SYSTEM IS EXPECTED TO MAINTAIN THIS SOUTHEASTWARD TRACK THROUGH TAU 24 WHERE IT TURNS TO A GENERALLY EASTWARD TRACK. BY TAU 24, THE SYSTEM SHOULD BEGIN SUBTROPICAL TRANSITION AS IT MOVES INTO COOLER (LESS THAN 26 C) WATERS AND INTERACTS WITH THE TROUGH. THROUGHOUT THE FORECAST PERIOD, TC 23P SHOULD STEADILY WEAKEN AS PERSISTENT HIGH VWS IMPACTS THE SYSTEM, WEAKENING TO 45 KTS BY TAU 48. THE SYSTEM SHOULD COMPLETE SUBTROPICAL TRANSITION BY TAU 48, IF NOT SOONER. NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU 24. AFTERWARDS, THE SOLUTIONS BEGIN TO DIVERGE. THE TRACK FORECAST IS PLACED CLOSE TO THE PREVIOUS JTWC FORECAST, AND SLIGHTLY NORTH OF THE MULTI-MODEL CONSENSUS TO OFFSET NAVGEM'S SOUTHERN OUTLIER TRACK. THERE IS HIGH CONFIDENCE IN THE FIRST 24 HOURS OF THE FORECAST TRACK AND LOW CONFIDENCE THEREAFTER DUE TO THE INCREASING SPREAD IN MODEL SOLUTIONS. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 060000Z IS 42 FEET. NEXT WARNINGS AT 060900Z, 061500Z, 062100Z AND 070300Z.// NNNN