WTXS31 PGTW 030300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 18S (EIGHTEEN) WARNING NR 011// RMKS/ 1. TROPICAL CYCLONE 18S (EIGHTEEN) WARNING NR 011 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 030000Z --- NEAR 23.7S 114.3E MOVEMENT PAST SIX HOURS - 340 DEGREES AT 05 KTS POSITION ACCURATE TO WITHIN 015 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: 23.7S 114.3E --- FORECASTS: 12 HRS, VALID AT: 031200Z --- 23.7S 114.1E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 24 HR POSIT: 240 DEG/ 02 KTS --- 24 HRS, VALID AT: 040000Z --- 23.9S 113.7E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 36 HR POSIT: 240 DEG/ 03 KTS --- 36 HRS, VALID AT: 041200Z --- 24.2S 113.1E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 000 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 000 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 215 DEG/ 02 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 050000Z --- 24.6S 112.8E 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 050 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 175 DEG/ 05 KTS --- 72 HRS, VALID AT: 060000Z --- 26.6S 112.9E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER --- REMARKS: 030300Z POSITION NEAR 23.7S 114.2E. 03FEB21. TROPICAL CYCLONE 18S (EIGHTEEN), LOCATED APPROXIMATELY 85 NM SOUTH OF LEARMONTH, AUSTRALIA, HAS TRACKED NORTH- NORTHWESTWARD AT 05 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTAL SATELLITE IMAGERY SHOWS THE SYSTEM MAINTAINED ITS DEEP CONVECTIVE STRUCTURE AS IT TRACKED OVER LAND SOUTH OF LEARMONTH. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON A WELL- DEFINED LOW LEVEL CIRCULATION FEATURE EVIDENT ON THE ABOM COMPOSITE RADAR LOOP THAT ALSO SHOWED ORGANIZED RAIN BANDS FROM THE NORTH AND SOUTH WRAPPING INTO THE CENTER. THE INITIAL INTENSITY OF 30KTS IS BASED ON THE SUSTAINED CONVECTIVE STRUCTURE AND EXTRAPOLATED FROM MULTIPLE SURFACE OBSERVATIONS ALONG THE COAST. UPPER-LEVEL ANALYSIS INDICATES RADIAL OUTFLOW AND LOW (05-10KT) VERTICAL WIND SHEAR (VWS). TC 18S WILL BECOME QUASI-STATIONARY (QS) AS THE STR TO THE SOUTHEAST RECEDES AND A SECONDARY STR BUILDING TO THE SOUTHWEST SLOWLY ASSUMES STEERING, RESULTING IN A VERY SLOW WEST-SOUTHWESTWARD TRACK TO TAU 36 AS THE TC EXITS INTO THE INDIAN OCEAN. AFTER TAU 36, THE SECONDARY STR WEAKENS, ALLOWING THE PRIMARY STR TO RESUME STEERING AND DRIVE THE TC SOUTHWESTWARD THEN SOUTHWARD. TC 18S IS EXPECTED TO MAINTAIN INTENSITY WHILE IT TRACKS OVER LAND BUT WILL INTENSIFY TO 35 KNOTS AFTER IT EXITS INTO THE WARM (28C) INDIAN OCEAN. THE WARM SST PLUS LOW VWS WILL SUSTAIN THE 35-KT INTENSITY TO TAU 48. AFTERWARD, COOLING SST AND INCREASING VWS WILL GRADUALLY ERODE THE SYSTEM TO DISSIPATION BY TAU 72. POSSIBLY SOONER. NUMERICAL MODELS ARE IN FAIRLY GOOD AGREEMENT WITH MINIMAL SPREADING; HOWEVER, THE UNCERTAINTY IN THE QS MOTION IN THE EARLY PORTION, LENDS AN OVERALL LOW CONFIDENCE TO THE JTWC TRACK FORECAST. NEXT WARNINGS AT 030900Z, 031500Z, 032100Z AND 040300Z.// NNNN