WTPS31 PGTW 052100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 23P (NIRAN) WARNING NR 020// RMKS/ 1. TROPICAL CYCLONE 23P (NIRAN) WARNING NR 020 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 051800Z --- NEAR 19.9S 161.4E MOVEMENT PAST SIX HOURS - 115 DEGREES AT 24 KTS POSITION ACCURATE TO WITHIN 010 NM POSITION BASED ON EYE FIXED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 130 KT, GUSTS 160 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 070 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 105 NM NORTHEAST QUADRANT 085 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 215 NM NORTHEAST QUADRANT 155 NM SOUTHEAST QUADRANT 120 NM SOUTHWEST QUADRANT 200 NM NORTHWEST QUADRANT REPEAT POSIT: 19.9S 161.4E --- FORECASTS: 12 HRS, VALID AT: 060600Z --- 22.4S 166.1E MAX SUSTAINED WINDS - 110 KT, GUSTS 135 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 090 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 250 NM NORTHEAST QUADRANT 170 NM SOUTHEAST QUADRANT 140 NM SOUTHWEST QUADRANT 170 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 120 DEG/ 27 KTS --- 24 HRS, VALID AT: 061800Z --- 24.8S 171.3E MAX SUSTAINED WINDS - 085 KT, GUSTS 105 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 020 NM NORTHEAST QUADRANT 010 NM SOUTHEAST QUADRANT 010 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 070 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 220 NM NORTHEAST QUADRANT 150 NM SOUTHEAST QUADRANT 130 NM SOUTHWEST QUADRANT 160 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 115 DEG/ 28 KTS --- 36 HRS, VALID AT: 070600Z --- 26.9S 177.0E MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING SUBTROPICAL RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 180 NM NORTHEAST QUADRANT 130 NM SOUTHEAST QUADRANT 120 NM SOUTHWEST QUADRANT 150 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 110 DEG/ 24 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 071800Z --- 28.3S 177.8W MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING SUBTROPICAL RADIUS OF 034 KT WINDS - 130 NM NORTHEAST QUADRANT 110 NM SOUTHEAST QUADRANT 090 NM SOUTHWEST QUADRANT 140 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 100 DEG/ 17 KTS --- 72 HRS, VALID AT: 081800Z --- 29.2S 169.9W MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY SUBTROPICAL RADIUS OF 034 KT WINDS - 080 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 090 NM SOUTHWEST QUADRANT 130 NM NORTHWEST QUADRANT --- REMARKS: 052100Z POSITION NEAR 20.5S 162.6E. 05MAR21. TROPICAL CYCLONE (TC) 23P (NIRAN), LOCATED APPROXIMATELY 294 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 REVEALS A 12 NM EYE WITH COOLING CLOUD TOP TEMPERATURES SURROUNDED BY A WEAKENING CONVECTIVE STRUCTURE. A 051741Z SSMIS 89 GHZ MICROWAVE IMAGE DEPICTS A TIGHT MICROWAVE EYE FEATURE WITH A SLIGHT BREAK IN THE EASTERN SEMICIRCLE OF THE EYEWALL. THESE EYE FEATURES LEND GOOD CONFIDENCE TO THE INITIAL POSITION WHICH IS IN EXCELLENT AGREEMENT WITH THE AGENCY FIXES. THE INITIAL INTENSITY OF 130 KTS IS HEDGED SLIGHTLY UNDER MULTI-AGENCY DVORAK CURRENT INTENSITY ESTIMATES OF T7.0 (140KTS) BASED ON A SATCON ESTIMATE OF 133 KTS, A CIMSS ADVANCED DVORAK TECHNIQUE ESTIMATE OF T6.5 (127 KTS), AND AN OVERALL RAPIDLY WEAKENING TREND IN THE SYSTEM STRUCTURE. TC 23P IS TRANSITING THROUGH A MARGINALLY FAVORABLE ENVIRONMENT CHARACTERIZED BY ROBUST POLEWARD UPPER LEVEL OUTFLOW AND WARM (28-29 C) SEA SURFACE TEMPERATURES OFFSET BY HIGH (25-30 KTS) VERTICAL WIND SHEAR (VWS). 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 48 WHERE IT TURNS TO A GENERALLY EASTWARD TRACK. BY TAU 36, 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 40 KTS BY TAU 72. THE SYSTEM SHOULD COMPLETE SUBTROPICAL TRANSITION BY TAU 72, IF NOT SOONER. NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU 24. AFTERWARDS, THE SOLUTIONS BEGIN TO DIVERGE TO A SPREAD OF 453 NM BY TAU 72. THE JTWC TRACK FORECAST LIES ALONG THE MULTI-MODEL CONSENSUS THROUGH TAU 24 AND THEN TRACKS ALONG THE NORTHERN EDGE OF THE MODEL GUIDANCE NEAR THE ECMWF TRACK SOLUTION FOR THE REMAINDER OF THE FORECAST. 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 051800Z IS 48 FEET. NEXT WARNINGS AT 060300Z, 060900Z, 061500Z AND 062100Z.// NNNN