WTPS31 PGTW 061500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 23P (NIRAN) WARNING NR 023// RMKS/ 1. TROPICAL CYCLONE 23P (NIRAN) WARNING NR 023 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 061200Z --- NEAR 24.3S 169.5E MOVEMENT PAST SIX HOURS - 120 DEGREES AT 31 KTS POSITION ACCURATE TO WITHIN 020 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 050 NM NORTHEAST QUADRANT 055 NM SOUTHEAST QUADRANT 045 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT 090 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 160 NM NORTHEAST QUADRANT 230 NM SOUTHEAST QUADRANT 130 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT REPEAT POSIT: 24.3S 169.5E --- FORECASTS: 12 HRS, VALID AT: 070000Z --- 26.9S 175.5E MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING SUBTROPICAL RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT 010 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 200 NM NORTHEAST QUADRANT 140 NM SOUTHEAST QUADRANT 120 NM SOUTHWEST QUADRANT 170 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 115 DEG/ 31 KTS --- 24 HRS, VALID AT: 071200Z --- 29.4S 178.0W MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING SUBTROPICAL 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: 105 DEG/ 31 KTS --- 36 HRS, VALID AT: 080000Z --- 30.7S 171.1W MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY SUBTROPICAL RADIUS OF 034 KT WINDS - 140 NM NORTHEAST QUADRANT 100 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 140 NM NORTHWEST QUADRANT --- REMARKS: 061500Z POSITION NEAR 25.0S 171.0E. 06MAR21. TROPICAL CYCLONE 23P (NIRAN), LOCATED APPROXIMATELY 229 NM SOUTHEAST OF NOUMEA, NEW CALEDONIA, HAS TRACKED EAST-SOUTHEASTWARD AT 31 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS THE SYSTEM HAS CONTINUED TO ELONGATED WITH FRONTAL CHARACTERISTICS MORE PRONOUNCED AS IT ACCELERATED TO THE SOUTHEAST. THE INITIAL POSITION WAS PLACED WITH HIGH CONFIDENCE BASED ON A CIRCULATION FEATURE IN THE 061059Z ASCAT BULLSEYE PASS. THE INITIAL INTENSITY OF 90KTS IS BASED ON THE PGTW/KNES DVORAK FINAL-T ESTIMATES OF T5.0/90KTS AND REFLECTS THE RAPID WEAKENING. UPPER LEVEL ANALYSIS INDICATES ROBUST POLEWARD OUTFLOW THAT IS OFFSET BY STRONG (30KTS+) VERTICAL WIND SHEAR. SEA SURFACE TEMPERATURES (SSTS) HAVE ALSO DROPPED TO 26C. THE CYCLONE WILL CONTINUE TO ACCELERATE SOUTHEASTWARD ALONG THE SOUTHWEST PERIPHERY OF THE DEEP LAYERED SUBTROPICAL RIDGE TO THE EAST. THE UNFAVORABLE ENVIRONMENT WILL SUSTAIN THE RAPID WEAKENING DOWN TO 40KTS BY TAU 36. CONCURRENTLY, TC NIRAN WILL BEGIN SUBTROPICAL TRANSITION BY TAU 12 AND BY TAU 36 WILL BECOME A GALE-FORCE SUBTROPICAL LOW, POSSIBLY SOONER. NUMERICAL MODELS ARE IN GOOD AGREEMENT THROUGH TAU 24. AFTERWARD, THE SOLUTIONS DIVERGE. 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 061200Z IS 45 FEET. NEXT WARNINGS AT 062100Z, 070300Z, 070900Z AND 071500Z.// NNNN