WTPS31 PGTW 040900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 23P (NIRAN) WARNING NR 014// RMKS/ 1. TROPICAL CYCLONE 23P (NIRAN) WARNING NR 014 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 040600Z --- NEAR 15.5S 149.5E MOVEMENT PAST SIX HOURS - 110 DEGREES AT 09 KTS POSITION ACCURATE TO WITHIN 020 NM POSITION BASED ON EYE FIXED BY A COMBINATION OF SATELLITE AND RADAR PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 050 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 115 NM NORTHEAST QUADRANT 075 NM SOUTHEAST QUADRANT 065 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 205 NM NORTHEAST QUADRANT 110 NM SOUTHEAST QUADRANT 130 NM SOUTHWEST QUADRANT 170 NM NORTHWEST QUADRANT REPEAT POSIT: 15.5S 149.5E --- FORECASTS: 12 HRS, VALID AT: 041800Z --- 16.4S 151.8E MAX SUSTAINED WINDS - 105 KT, GUSTS 130 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 050 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 210 NM NORTHEAST QUADRANT 160 NM SOUTHEAST QUADRANT 140 NM SOUTHWEST QUADRANT 200 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 115 DEG/ 19 KTS --- 24 HRS, VALID AT: 050600Z --- 18.0S 155.3E MAX SUSTAINED WINDS - 120 KT, GUSTS 145 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 050 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 230 NM NORTHEAST QUADRANT 160 NM SOUTHEAST QUADRANT 140 NM SOUTHWEST QUADRANT 210 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 120 DEG/ 21 KTS --- 36 HRS, VALID AT: 051800Z --- 20.0S 159.2E MAX SUSTAINED WINDS - 115 KT, GUSTS 140 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 070 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 250 NM NORTHEAST QUADRANT 160 NM SOUTHEAST QUADRANT 150 NM SOUTHWEST QUADRANT 190 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 120 DEG/ 22 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 060600Z --- 22.0S 163.4E MAX SUSTAINED WINDS - 095 KT, GUSTS 115 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING SUBTROPICAL RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 100 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 250 NM NORTHEAST QUADRANT 170 NM SOUTHEAST QUADRANT 160 NM SOUTHWEST QUADRANT 170 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 115 DEG/ 26 KTS --- 72 HRS, VALID AT: 070600Z --- 26.0S 173.8E MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING SUBTROPICAL RADIUS OF 064 KT WINDS - 010 NM NORTHEAST QUADRANT 010 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 190 NM NORTHEAST QUADRANT 160 NM SOUTHEAST QUADRANT 130 NM SOUTHWEST QUADRANT 160 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 110 DEG/ 26 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 080600Z --- 29.1S 175.1W MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY SUBTROPICAL 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 - 160 NM NORTHEAST QUADRANT 130 NM SOUTHEAST QUADRANT 130 NM SOUTHWEST QUADRANT 170 NM NORTHWEST QUADRANT --- REMARKS: 040900Z POSITION NEAR 15.7S 150.1E. 04MAR21. TROPICAL CYCLONE 23P (NIRAN), LOCATED APPROXIMATELY 229 NM EAST-NORTHEAST OF CAIRNS, AUSTRALIA, HAS TRACKED EAST- SOUTHEASTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A 13-NM CLOUD FILLED EYE WITH DEEP CONVECTION SURROUNDING THREE OF FOUR QUADRANTS. THE COMBINATION OF THE MSI, ANIMATED RADAR DATA FROM WILLIS ISLAND AND A 040610Z SSMIS 91GHZ MICROWAVE IMAGE PROVIDED HIGH CONFIDENCE TO THE INITIAL POSITION. OVERALL MOTION HAS INCREASED TOWARDS TO THE SOUTHEAST, HOWEVER THE LATEST DATA FROM THE WILLIS ISLAND RADAR SEEM TO INDICATE THAT THE SYSTEM MAY HAVE ONCE AGAIN BECOME QUASI- STATIONARY OR AT LEAST SIGNIFICANTLY SLOWED DOWN. THE INITIAL INTENSITY IS ASSESSED AT 90 KTS WITH HIGH CONFIDENCE AND HEDGED SLIGHTLY LOWER THAN A 5.5 (102 KTS) DVORAK CURRENT INTENSITY ESTIMATE FROM PGTW IN LIGHT OF A T5.0 ESTIMATE FROM ABRF, AN ADT ESTIMATE OF T4.9 AND A SATCON ESTIMATE OF 89 KTS. TC 23P CURRENTLY LIES IN AN ENVIRONMENT CONDUCIVE TO FURTHER DEVELOPMENT CHARACTERIZED BY WARM (29-30C) SSTS, LOW (5-10 KTS) VWS AND GOOD, NEARLY RADIAL OUTFLOW ALOFT. TAKING INTO ACCOUNT THE NEAR-TERM SLOW DOWN IN FORWARD MOTION, TC 23P REMAINS COCOONED IN A COMPETING STEERING PATTERN, BETWEEN THE STRONG NEAR-EQUATORIAL RIDGE (NER) TO THE NORTHEAST AND A SUBTROPICAL RIDGE (STR) ENTRENCHED OVER CENTRAL AUSTRALIA. HOWEVER, ALL MODEL GUIDANCE AGREES THAT IN THE NEAR-TERM, TC 23P WILL ACCELERATE SOUTHEASTWARD AS THE NER BECOMES THE DOMINATE STEERING MECHANISM, INCREASING FORWARD SPEED AS IT MOVES UNDER THE ENHANCED GRADIENT BETWEEN THE NER TO THE NORTHEAST AND A MAJOR SHORTWAVE TROUGH APPROACHING FROM THE WEST. THE PRESENCE OF A SMALL EYE AND A CYAN RING FEATURE IN A 040359Z AMSR2 37GHZ COLOR COMPOSITE IMAGE INDICATE A HIGH LIKELIHOOD OF A PERIOD OF RAPID INTENSIFICATION IN THE NEAR-TERM. OVER THE NEXT 24-36 HOURS, OUTFLOW WILL IMPROVE SUBSTANTIALLY AS IT BEGINS TO TAP INTO THE THE DIVERGENT FLOW AHEAD THE APPROACHING MAJOR SHORTWAVE TROUGH, ALLOWING FOR A SHORT PERIOD OF RAPID INTENSIFICATION, PEAKING AT 120 KTS AT TAU 24, BEFORE INCREASING VWS BEGINS SLOWLY WEAKEN THE SYSTEM. THE SYSTEM IS EXPECTED TO BEGIN SUBTROPICAL TRANSITION BY TAU 48, AS IT RIDES SOUTHEAST ALONG THE NORTHERN EDGE OF THE BAROCLINIC ZONE AND MOVES UNDER THE STRONG WESTERLIES, AND SHOULD COMPLETE TRANSITION TO A STORM FORCE SUBTROPICAL LOW BY TAU 96. NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU 48, WITH SPREAD INCREASING TO 760NM BETWEEN THE NAVGEM AND GFS OUTLIERS AT TAU 96. THE JTWC FORECAST DISCOUNTS THE UNREALISTIC NAVGEM SOLUTION, AND LIES ON THE NORTHERN SIDE OF THE GUIDANCE ENVELOPE CLOSE TO THE ECMWF SOLUTION WITH MODERATE CONFIDENCE. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 040600Z IS 32 FEET. NEXT WARNINGS AT 041500Z, 042100Z, 050300Z AND 050900Z. // NNNN