WTPS31 PGTW 051500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 23P (NIRAN) WARNING NR 019// RMKS/ 1. TROPICAL CYCLONE 23P (NIRAN) WARNING NR 019 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 051200Z --- NEAR 18.8S 159.1E MOVEMENT PAST SIX HOURS - 115 DEGREES AT 24 KTS POSITION ACCURATE TO WITHIN 020 NM POSITION BASED ON EYE FIXED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 140 KT, GUSTS 170 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 060 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 115 NM NORTHEAST QUADRANT 100 NM SOUTHEAST QUADRANT 065 NM SOUTHWEST QUADRANT 115 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 225 NM NORTHEAST QUADRANT 175 NM SOUTHEAST QUADRANT 125 NM SOUTHWEST QUADRANT 215 NM NORTHWEST QUADRANT REPEAT POSIT: 18.8S 159.1E --- FORECASTS: 12 HRS, VALID AT: 060000Z --- 21.0S 163.7E MAX SUSTAINED WINDS - 135 KT, GUSTS 165 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 - 080 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 240 NM NORTHEAST QUADRANT 180 NM SOUTHEAST QUADRANT 140 NM SOUTHWEST QUADRANT 170 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 120 DEG/ 25 KTS --- 24 HRS, VALID AT: 061200Z --- 23.5S 168.5E MAX SUSTAINED WINDS - 120 KT, GUSTS 145 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 020 NM NORTHEAST QUADRANT 010 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 070 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 220 NM NORTHEAST QUADRANT 170 NM SOUTHEAST QUADRANT 130 NM SOUTHWEST QUADRANT 150 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 115 DEG/ 26 KTS --- 36 HRS, VALID AT: 070000Z --- 25.7S 173.7E MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING SUBTROPICAL RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT 000 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 190 NM NORTHEAST QUADRANT 140 NM SOUTHEAST QUADRANT 110 NM SOUTHWEST QUADRANT 140 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 110 DEG/ 26 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 071200Z --- 27.5S 179.1E 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 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 140 NM NORTHEAST QUADRANT 090 NM SOUTHEAST QUADRANT 090 NM SOUTHWEST QUADRANT 130 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 105 DEG/ 20 KTS --- 72 HRS, VALID AT: 081200Z --- 29.2S 171.8W MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY SUBTROPICAL RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT --- REMARKS: 051500Z POSITION NEAR 19.4S 160.2E. 05MAR21. TROPICAL CYCLONE 23P (NIRAN), LOCATED APPROXIMATELY 440 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 SHOWS THAT TC 23P HAS UNDERGONE A PERIOD OF EXTREME RAPID INTENSIFICATION (ERI), HAVING INTENSIFIED 30 KTS IN SIX HOURS, WITH DEVELOPMENT OF A VERY COMPACT 10NM EYE, SURROUNDED BY A UNIFORM RING OF VERY COLD CONVECTIVE CLOUD TOPS. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE SMALL EYE FEATURE IN THE INFRARED IMAGERY. THE INITIAL INTENSITY IS ASSESSED AT 140 KTS WITH HIGH CONFIDENCE BASED ON A PGTW T7.0 DVORAK CURRENT INTENSITY ESTIMATE, A CIMSS ADT CONSTRAINED ESTIMATE OF T6.3, WITH A RAW ESTIMATE OF T7.0, AND A SATCON ESTIMATE OF 135 KTS. THE ENVIRONMENT IS GENERALLY FAVORABLE, THOUGH VERTICAL WIND SHEAR IS INCREASING TO 20 TO 25 KTS. HOWEVER, THE SHEAR VECTOR IS IN PHASE WITH THE STORM MOTION RESULTING IN SOMEWHAT LOWER RELATIVE VWS WHICH, COMBINED WITH WARM (28-29C) SSTS AND VERY STRONG POLEWARD OUTFLOW, HAS ENABLED THE RECENT ERI. TC 23P IS MOVING RAPIDLY SOUTHEASTWARD IN THE TIGHT UPPER-LEVEL GRADIENT BETWEEN A DEEP-LAYER RIDGE COMPLEX EXTENDING FROM FIJI NORTHWEST TO THE EQUATOR AND AN APPROACHING MAJOR SHORTWAVE TROUGH APPROACHING FROM THE WEST. THIS SOUTHEASTWARD MOTION IS FORECAST TO CONTINUE THROUGH TAU 48, BEFORE TURNING MORE EASTWARD AT TAU 72. TC 23P IS FORECAST TO SLOWLY WEAKEN OVER THE NEXT 12 HOURS AS THE ROBUST POLEWARD OUTFLOW OFFSETS THE STEADILY INCREASING, BUT IN PHASE, VWS. AFTER TAU 24 THE RATE OF WEAKENING WILL INCREASE AS DIFFLUENT UPPER-LEVEL OUTFLOW WEAKENS, VWS INCREASES AND THE SYSTEM MOVES OVER COOLER WATERS. THE SYSTEM WILL BEGIN SUBTROPICAL TRANSITION BY TAU 36 AS IT MOVES BEGINS TO INTERACT WITH AND EVENTUALLY MOVE UNDER THE APPROACHING TROUGH AND INTO MUCH COOLER WATERS. TRANSITION TO A STORM FORCE SUBTROPICAL LOW IS EXPECTED NO LATER THAN TAU 72, OR POTENTIALLY AS EARLY AS TAU 60. NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT, WITH 150NM SPREAD AT TAU 36. GUIDANCE IS IN POOR AGREEMENT AFTER TAU 36, WITH A 585NM SPREAD BY TAU 72. THE JTWC FORECAST LIES NEAR THE CONSENSUS MEAN THROUGH TAU 36, THEN TRACKS THE NORTHERN EDGE OF THE BULK OF THE GUIDANCE AND CLOSE TO THE ECMWF SOLUTION THOUGH TAU 72. IN LIGHT OF THE UNCERTAINTY SEEN IN THE LATER TAUS, THERE IS HIGH CONFIDENCE IN THE FIRST 36 HOURS AND LOW CONFIDENCE THEREAFTER. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 051200Z IS 50 FEET. NEXT WARNINGS AT 052100Z, 060300Z, 060900Z AND 061500Z.// NNNN