WTPS31 PGTW 041500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 23P (NIRAN) WARNING NR 015// RMKS/ 1. TROPICAL CYCLONE 23P (NIRAN) WARNING NR 015 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 041200Z --- NEAR 15.4S 150.4E MOVEMENT PAST SIX HOURS - 085 DEGREES AT 09 KTS POSITION ACCURATE TO WITHIN 030 NM POSITION BASED ON CENTER LOCATED BY A COMBINATION OF SATELLITE AND RADAR PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 085 KT, GUSTS 105 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 105 NM NORTHEAST QUADRANT 065 NM SOUTHEAST QUADRANT 065 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 210 NM NORTHEAST QUADRANT 115 NM SOUTHEAST QUADRANT 120 NM SOUTHWEST QUADRANT 190 NM NORTHWEST QUADRANT REPEAT POSIT: 15.4S 150.4E --- FORECASTS: 12 HRS, VALID AT: 050000Z --- 16.1S 153.1E MAX SUSTAINED WINDS - 095 KT, GUSTS 115 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 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 080 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 220 NM NORTHEAST QUADRANT 150 NM SOUTHEAST QUADRANT 140 NM SOUTHWEST QUADRANT 200 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 120 DEG/ 21 KTS --- 24 HRS, VALID AT: 051200Z --- 18.0S 157.0E 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 050 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 240 NM NORTHEAST QUADRANT 160 NM SOUTHEAST QUADRANT 150 NM SOUTHWEST QUADRANT 200 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 125 DEG/ 24 KTS --- 36 HRS, VALID AT: 060000Z --- 20.6S 161.2E MAX SUSTAINED WINDS - 105 KT, GUSTS 130 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 - 090 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 240 NM NORTHEAST QUADRANT 170 NM SOUTHEAST QUADRANT 150 NM SOUTHWEST QUADRANT 180 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 115 DEG/ 27 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 061200Z --- 23.0S 166.5E MAX SUSTAINED WINDS - 085 KT, GUSTS 105 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING SUBTROPICAL RADIUS OF 064 KT WINDS - 020 NM NORTHEAST QUADRANT 010 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 090 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 230 NM NORTHEAST QUADRANT 170 NM SOUTHEAST QUADRANT 150 NM SOUTHWEST QUADRANT 170 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 115 DEG/ 26 KTS --- 72 HRS, VALID AT: 071200Z --- 27.0S 177.0E 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 020 NM SOUTHEAST QUADRANT 000 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 170 NM NORTHEAST QUADRANT 140 NM SOUTHEAST QUADRANT 120 NM SOUTHWEST QUADRANT 150 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 110 DEG/ 24 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 081200Z --- 29.6S 172.7W MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY SUBTROPICAL RADIUS OF 050 KT WINDS - 080 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 130 NM NORTHEAST QUADRANT 110 NM SOUTHEAST QUADRANT 120 NM SOUTHWEST QUADRANT 140 NM NORTHWEST QUADRANT --- REMARKS: 041500Z POSITION NEAR 15.6S 151.1E. 04MAR21. TROPICAL CYCLONE 23P (NIRAN), LOCATED APPROXIMATELY 280 NM EAST-NORTHEAST OF CAIRNS, AUSTRALIA, HAS TRACKED EASTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THAT THE EYE THAT WAS SO CLEARLY EVIDENT SIX HOURS AGO HAS NOW COMPLETELY FILLED. THE CONVECTIVE STRUCTURE HAS ALSO DETERIORATED OVER THE PAST SIX HOURS, WITH LITTLE IN THE WAY OF DEEP CONVECTION IN THE SOUTHERN AND SOUTHWESTERN QUADRANTS, AS CONFIRMED BY A 101142Z AMSU-B 89GHZ COLOR COMPOSITE IMAGE SHOWING A CURVED BAND OF CONVECTION TO THE NORTH AND A ONLY LOW LEVEL BANDS WRAPPING IN FROM THE SOUTH. THE SATELLITE DATA ALSO CONFIRMS A MODERATE EASTERLY WIND SHEAR, INDICATED BY THE SHARP UP-SHEAR (EASTERN) EDGE OF THE CONVECTIVE CLOUD STRUCTURE. ANIMATED RADAR DATA FROM WILLIS ISLAND CONFIRMED THE RECENT EASTWARD JOG OF THE LOW LEVEL CIRCULATION CENTER (LLCC) AND LENT HIGH CONFIDENCE TO THE INITIAL POSITION. THE INITIAL INTENSITY WAS LOWERED SLIGHTLY, TO 85 KNOTS BASED ON AN AVERAGE OF BOTH SUBJECTIVE AND OBJECTIVE DVORAK INTENSITY ESTIMATES RANGING BETWEEN T4.7 TO T5.0. AS THE RECENT JOG TO THE EAST INDICATES, THE SYSTEM REMAINS IN A RELATIVELY WEAK STEERING ENVIRONMENT BETWEEN THE SUBTROPICAL RIDGE (STR) TO THE WEST AND A NEAR EQUATORIAL RIDGE (NER) TO THE EAST. OVER THE NEXT FEW HOURS HOWEVER, THE NER SHOULD GAIN PREDOMINANCE AS THE PRIMARY STEERING MECHANISM, RESULTING IN A SOUTHEASTWARD TRACK. ONCE ESTABLISHED ON THE SOUTHEASTWARD TRACK, TC 23P WILL STEADILY ACCELERATE AS IT BECOMES EMBEDDED WITHIN THE STRONG GRADIENT BETWEEN THE BUILDING RIDGE TO THE EAST AND AN APPROACHING MID-LATITUDE MAJOR SHORTWAVE TROUGH APPROACHING FROM THE WEST. THE SYSTEM IS EXPECTED TO INTENSIFY TO A PEAK OF 110 KTS BY TAU 24 AS IT ENTERS A SHORT PERIOD OF VERY STRONG POLEWARD OUTFLOW AND RELATIVELY LOW VWS. THIS INTENSIFICATION WILL BE SHORT-LIVED AND BY TAU 36, THE STEADILY INCREASING VWS AND COOLER SSTS WILL CONSPIRE TO WEAKEN THE SYSTEM AS IT RAPIDLY TRANSLATES TO THE SOUTHEAST. TC 23P IS FORECAST TO BEGIN SUBTROPICAL TRANSITION BY TAU 48 AND COMPLETE TRANSITION TO A STORM FORCE SUBTROPICAL LOW BY TAU 72. NUMERICAL MODEL GUIDANCE IS IN VERY TIGHT AGREEMENT THROUGH TAU 24 WITH SPREAD OF ONLY 50, INCREASING TO 140NM BY TAU 48. AS THE SYSTEM PASSES NEW CALEDONIA AND BEGINS TO TRANSITION TO SUBTROPICAL, THE GUIDANCE BECOMES INCREASINGLY UNCERTAIN WITH SOME MODELS (NVGM) UNREALISTICALLY MOVING THE SYSTEM WELL TO THE SOUTH OF NEW ZEALAND, WHILE THE REMAINDER OF THE CONSENSUS MEMBERS SHOW A SLOW TURN TOWARDS THE EAST AFTER TAU 72, AS A STRONG TRANSIENT HIGH PRESSURE AREA DEVELOPS EAST OF NEW ZEALAND. THE JTWC LIES CLOSE TO THE ECMWF SOLUTION, TO THE NORTH OF THE CONSENSUS MEAN TRACK AFTER TAU 48. WHILE THERE IS HIGH CONFIDENCE IN THE FIRST PORTION OF THE FORECAST, THERE IS LOW CONFIDENCE IN THE EXTENDED TAUS. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 041200Z IS 32 FEET. NEXT WARNINGS AT 042100Z, 050300Z, 050900Z AND 051500Z.// NNNN