WTPS31 PGTW 060900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 23P (NIRAN) WARNING NR 022// RMKS/ 1. TROPICAL CYCLONE 23P (NIRAN) WARNING NR 022 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 060600Z --- NEAR 22.7S 166.6E MOVEMENT PAST SIX HOURS - 120 DEGREES AT 31 KTS POSITION ACCURATE TO WITHIN 025 NM POSITION BASED ON CENTER LOCATED BY A COMBINATION OF SATELLITE AND SYNOPTIC DATA PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 100 KT, GUSTS 125 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 060 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 120 NM NORTHEAST QUADRANT 100 NM SOUTHEAST QUADRANT 085 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 215 NM NORTHEAST QUADRANT 155 NM SOUTHEAST QUADRANT 110 NM SOUTHWEST QUADRANT 180 NM NORTHWEST QUADRANT REPEAT POSIT: 22.7S 166.6E --- FORECASTS: 12 HRS, VALID AT: 061800Z --- 25.5S 172.4E MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT 010 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 060 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/ 32 KTS --- 24 HRS, VALID AT: 070600Z --- 28.1S 178.9E MAX SUSTAINED WINDS - 055 KT, GUSTS 070 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: 110 DEG/ 30 KTS --- 36 HRS, VALID AT: 071800Z --- 30.2S 174.7W MAX SUSTAINED WINDS - 045 KT, GUSTS 055 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: 060900Z POSITION NEAR 23.4S 168.0E. 06MAR21. TROPICAL CYCLONE 23P (NIRAN), LOCATED APPROXIMATELY 45 NM SOUTHEAST OF NOUMEA, NEW CALEDONIA, HAS TRACKED EAST-SOUTHEASTWARD AT 31 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS THE SYSTEM HAS BECOME MORE ELONGATED WITH FRONTAL CHARACTERISTICS AS IT ACCELERATES TO THE SOUTHEAST. ADDITIONALLY, COLD AIR STRATOCUMULUS CLOUDS CAN BE SEEN FEEDING TOWARD THE LOW LEVEL CIRCULATION. THE INITIAL POSITION WAS PLACED WITH HIGH CONFIDENCE BASED ON AN ELONGATED MICROWAVE EYE IN THE 0542Z SSMIS 37GHZ IMAGE. THE INITIAL INTENSITY OF 100KTS IS BASED ON AN OVERALL ASSESSMENT OF WEAKENING AGENCY DVORAK ESTIMATES AND HEDGED CLOSER TO THE OBJECTIVE ADT CURRENT INTENSITY ESTIMATE OF T5.3/97KTS. UPPER LEVEL ANALYSIS INDICATES STRONG POLEWARD OUTFLOW THAT IS OFFSET BY STRONG (30KTS+) VERTICAL WIND SHEAR. SEA SURFACE TEMPERATURES (SSTS) ARE CURRENTLY MARGINAL AT 27C. THE CYCLONE IS EXPECTED TO CONTINUE TO ACCELERATE SOUTHEASTWARD ALONG THE SOUTHWEST PERIPHERY OF THE DEEP LAYERED SUBTROPICAL RIDGE TO THE EAST. IN ADDITION TO THE HARSH UPPER LEVEL DYNAMICS, SSTS WILL GRADUALLY DROP, LEADING TO RAPID WEAKENING TO 45KTS BY TAU 36. CONCURRENTLY, TC NIRAN WILL BEGIN SUBTROPICAL TRANSITION BY TAU 24 AND BY TAU 36 WILL BECOME A SUBTROPICAL SYSTEM. NUMERICAL MODELS ARE IN GOOD AGREEMENT THROUGH TAU 24. AFTERWARDS, 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 060600Z IS 45 FEET. NEXT WARNINGS AT 061500Z, 062100Z, 070300Z AND 070900Z.// NNNN