WTPS31 PGTW 012100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 23P (NIRAN) WARNING NR 004// RMKS/ 1. TROPICAL CYCLONE 23P (NIRAN) WARNING NR 004 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 011800Z --- NEAR 15.3S 147.4E MOVEMENT PAST SIX HOURS - 030 DEGREES AT 09 KTS POSITION ACCURATE TO WITHIN 035 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 065 NM NORTHEAST QUADRANT 055 NM SOUTHEAST QUADRANT 080 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT REPEAT POSIT: 15.3S 147.4E --- FORECASTS: 12 HRS, VALID AT: 020600Z --- 15.0S 148.2E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 020 NM NORTHEAST QUADRANT 000 NM SOUTHEAST QUADRANT 000 NM SOUTHWEST QUADRANT 000 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 090 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 110 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 115 DEG/ 05 KTS --- 24 HRS, VALID AT: 021800Z --- 15.4S 149.2E MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 010 NM NORTHEAST QUADRANT 000 NM SOUTHEAST QUADRANT 000 NM SOUTHWEST QUADRANT 010 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 120 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 090 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 110 DEG/ 02 KTS --- 36 HRS, VALID AT: 030600Z --- 15.5S 149.5E MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 020 NM NORTHEAST QUADRANT 010 NM SOUTHEAST QUADRANT 010 NM SOUTHWEST QUADRANT 010 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 130 NM NORTHEAST QUADRANT 080 NM SOUTHEAST QUADRANT 090 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 110 DEG/ 02 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 031800Z --- 15.6S 149.8E MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 010 NM NORTHEAST QUADRANT 000 NM SOUTHEAST QUADRANT 000 NM SOUTHWEST QUADRANT 010 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 150 NM NORTHEAST QUADRANT 090 NM SOUTHEAST QUADRANT 090 NM SOUTHWEST QUADRANT 130 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 110 DEG/ 06 KTS --- 72 HRS, VALID AT: 041800Z --- 16.4S 152.0E MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 020 NM NORTHEAST QUADRANT 000 NM SOUTHEAST QUADRANT 000 NM SOUTHWEST QUADRANT 000 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 170 NM NORTHEAST QUADRANT 130 NM SOUTHEAST QUADRANT 110 NM SOUTHWEST QUADRANT 140 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 120 DEG/ 13 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 051800Z --- 19.1S 156.8E MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 090 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 180 NM NORTHEAST QUADRANT 140 NM SOUTHEAST QUADRANT 150 NM SOUTHWEST QUADRANT 170 NM NORTHWEST QUADRANT VECTOR TO 120 HR POSIT: 120 DEG/ 19 KTS --- 120 HRS, VALID AT: 061800Z --- 22.6S 163.8E MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 120 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 180 NM NORTHEAST QUADRANT 160 NM SOUTHEAST QUADRANT 140 NM SOUTHWEST QUADRANT 130 NM NORTHWEST QUADRANT --- REMARKS: 012100Z POSITION NEAR 15.2S 147.6E. 01MAR21. TROPICAL CYCLONE 23P (NIRAN), LOCATED APPROXIMATELY 133 NM NORTHEAST OF CAIRNS, AUSTRALIA, HAS TRACKED NORTH- NORTHEASTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY INDICATES FLARING CONVECTION CONSOLIDATING NEAR THE LOW LEVEL CIRCULATION (LLC). THE 011833Z SSMIS 37GHZ AND 91GHZ IMAGES INDICATE A SLIGHT TILT TO THE WEST BETWEEN THE SURFACE AND THE UPPER LEVELS. OBSERVATIONS FROM BOUGAINVILLE REEF AND ARLINGTON REEF INDICATE THE SYSTEM HAS PASSED TO THE EAST-NORTHEAST WITH INITIAL INTENSITY OF 45 KNOTS BASED ON AFOREMENTIONED SURFACE OBSERVATIONS, WHICH NOW SHOW SUSTAINED WINDS OF 40-45 KTS FROM THE PREVIOUS SIX HOURS. INITIAL INTENSITY IS HEDGED SLIGHTLY HIGHER THAN MULTIPLE AGENCY DVORAK INTENSITY ESTIMATES FOR PGTW/KNES OF T2.5 (35 KTS), ADT T2.7 (39KTS), AND FALL MORE IN LINE WITH ABRF T3.0 (45 KTS). THE MEAN SEA LEVEL PRESSURE AT BOUGAINVILLE REEF FELL TO A LOW VALUE OF 984 MB OVER THE PREVIOUS SIX HOURS, AND IS NOW BEGINNING TO RISE STEADILY TO 989 MB, SUPPORTING THE HIGHER INITIAL INTENSITY. THE MOVEMENT TO THE NORTHEAST IS ALSO SHOWN BY THE WINDS SHIFTING FROM THE NORTHWEST TO THE SOUTH-SOUTHEAST. THE OVERALL ENVIRONMENT IS INCREASINGLY FAVORABLE; VERTICAL WIND SHEAR (VWS) IS LOW (5-10 KTS) FROM THE NORTHEAST, SSTS ARE VERY WARM (29-30C) AND THE OUTFLOW PATTERN IS BEGINNING TO TAP INTO A SLIGHT POLEWARD OUTFLOW CHANNEL WITH WEAK EQUATORWARD OUTFLOW. THE STEERING PATTERN REMAINS COMPLEX, WITH THE SYSTEM TRAPPED BETWEEN A NEAR-EQUATORIAL RIDGE (NER) TO THE NORTHEAST AND A SUBTROPICAL RIDGE (STR) OVER CENTRAL AUSTRALIA. THE STRONGEST GRADIENT LIES SLIGHTLY TO THE WEST BETWEEN TC 23P AND THE STR OVER AUSTRALIA, LEADING TO THE CURRENT MOTION TOWARDS THE NORTHEAST. OVER THE NEXT 24 TO 36 HOURS THE STR TO THE WEST IS EXPECTED TO WEAKEN AND MOVE SOUTHWEST WHILE THE NER STRENGTHENS AND MOVES SOUTHWEST, INCREASING THE GRADIENT TO THE NORTHEAST OF THE SYSTEM, ALLOWING IT TO MOVE SOUTHEASTWARD BY TAU 24. ONCE ESTABLISHED ON THE SOUTHEASTWARD TRACK, THE SYSTEM WILL ACCELERATE AHEAD OF AN APPROACHING MAJOR SHORTWAVE TROUGH. BY TAU 48 AS THE SYSTEM STARTS TO MOVE CLOSER TO THE SHORTWAVE TROUGH, OUTFLOW WILL IMPROVE AS IT BEGINS TO TAP INTO THE DEEP WESTERLIES, ALLOWING FOR A FASTER RATE OF INTENSIFICATION, TO A PEAK OF 70 KTS BY TAU 72. AVAILABLE MODEL GUIDANCE SHOWS A HIGH DEGREE OF UNCERTAINTY AS WOULD BE EXPECTED FOR A SYSTEM IN A WEAK STEERING ENVIRONMENT. THE GFS STILL DEPICTS AN UNLIKELY TRACK TO THE NORTHWEST BEFORE TURNING EAST AFTER TAU 36. THE REMAINDER OF THE CONSENSUS MEMBERS AGREE ON ACCELERATING THE SYSTEM AFTER THE CLOCKWISE LOOP, HOWEVER, THERE IS A LARGE AMOUNT OF ALONG-TRACK UNCERTAINTY AFTER TAU 72. THE JTWC FORECAST TRACK LIES JUST EQUATORWARD OF THE MULTI-MODEL CONSENSUS. DUE TO THE LARGE ALONG-TRACK SPREAD IN LATER TAUS, THERE IS OVERALL LOW CONFIDENCE IN THE JTWC FORECAST TRACK. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 011800Z IS 18 FEET. NEXT WARNINGS AT 020300Z, 020900Z, 021500Z, AND 022100Z.// NNNN