WTXS31 PGTW 040300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 18S (EIGHTEEN) WARNING NR 015// RMKS/ 1. TROPICAL CYCLONE 18S (EIGHTEEN) WARNING NR 015 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 040000Z --- NEAR 24.3S 114.3E MOVEMENT PAST SIX HOURS - 220 DEGREES AT 07 KTS POSITION ACCURATE TO WITHIN 030 NM POSITION BASED ON CENTER LOCATED BY A COMBINATION OF SATELLITE, RADAR AND SYNOPTIC DATA PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY REPEAT POSIT: 24.3S 114.3E --- FORECASTS: 12 HRS, VALID AT: 041200Z --- 24.7S 113.5E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 24 HR POSIT: 235 DEG/ 03 KTS --- 24 HRS, VALID AT: 050000Z --- 25.1S 112.9E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 000 NM NORTHEAST QUADRANT 010 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 205 DEG/ 04 KTS --- 36 HRS, VALID AT: 051200Z --- 25.9S 112.5E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER RADIUS OF 034 KT WINDS - 000 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 175 DEG/ 09 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 060000Z --- 27.7S 112.7E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER --- REMARKS: 040300Z POSITION NEAR 24.4S 114.1E. 04FEB21. TROPICAL CYCLONE 18S (EIGHTEEN), LOCATED APPROXIMATELY 121 NM SOUTH OF LEARMONTH, AUSTRALIA, HAS TRACKED SOUTHWESTWARD AT 07 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS WEAKENING CONVECTION SHEARED TO THE EAST OF AN EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) LOCATED JUST NORTH OF CARNARVON. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE EXPOSED LLCC, SUPPORTED BY ANIMATED COMPOSITE RADAR DATA FROM CARNARVON. THE INITIAL INTENSITY IS ALSO ASSESSED WITH HIGH CONFIDENCE BASED ON SURFACE OBSERVATION DATA FROM CARNARVON WHICH INDICATED SUSTAINED WINDS BETWEEN 25-30 KTS WITH GUSTS ABOUT 35 KTS. THE SYSTEM LIES IN A GENERALLY MARGINAL TO SLIGHTLY FAVORABLE ENVIRONMENT CHARACTERIZED BY LOW (10-15 KT) VWS AND ROBUST POLEWARD OUTFLOW. HOWEVER, THE ANIMATED MSI SHOWS A BROAD AREA OF RELATIVELY STABLE STRATOCUMULUS FIELD EXTENDING FAR TO THE WEST OF THE AUSTRALIAN COAST AND WRAPPING INTO THE SYSTEM, WHICH WILL LIKELY SERVE AS A HINDRANCE TO MUCH ADDITIONAL DEVELOPMENT. THE SYSTEM HAS NOW STARTED ACCELERATING TO THE SOUTHWEST ALONG THE WESTERN PERIPHERY OF A DEEP- LAYER STR LOCATED TO THE NORTHEAST AND WILL ROUND THE RIDGE AXIS BY TAU 36 BEFORE TURNING TO THE SOUTH. SSTS IN THE AREA JUST OFFSHORE ARE ABOUT 26C, WHICH SHOULD ALLOW FOR A SLIGHT INTENSIFICATION TO 35 KNOTS BY TAU 24. THEREAFTER, RAPIDLY INCREASING WESTERLY VWS AND DECREASING SSTS (<25C) WILL QUICKLY WEAKEN THE SYSTEM, LEADING TO FULL DISSIPATION AS A TROPICAL CYCLONE BY TAU 48. NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT WITH INCREASING UNCERTAINTY AFTER TAU 12 AS THE CONSENSUS MEMBERS DISAGREE ON THE EXACT TIMING OF THE TURN TOWARDS THE SOUTH, LEADING TO A SPREAD OF 122NM BY TAU 48. THE JTWC FORECAST LIES FASTER AND TO THE LEFT OF THE MULTI-MODEL CONSENSUS WITH LOW CONFIDENCE. NEXT WARNINGS AT 040900Z, 041500Z, 042100Z AND 050300Z. // NNNN