WTXS31 PGTW 020300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 18S (EIGHTEEN) WARNING NR 007// RMKS/ 1. TROPICAL CYCLONE 18S (EIGHTEEN) WARNING NR 007 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 020000Z --- NEAR 22.1S 116.2E MOVEMENT PAST SIX HOURS - 235 DEGREES AT 10 KTS POSITION ACCURATE TO WITHIN 020 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: 22.1S 116.2E --- FORECASTS: 12 HRS, VALID AT: 021200Z --- 22.9S 114.7E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 24 HR POSIT: 250 DEG/ 04 KTS --- 24 HRS, VALID AT: 030000Z --- 23.2S 113.9E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 36 HR POSIT: 270 DEG/ 02 KTS --- 36 HRS, VALID AT: 031200Z --- 23.2S 113.4E 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 060 NM SOUTHWEST QUADRANT 010 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 285 DEG/ 02 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 040000Z --- 23.1S 113.0E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 000 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 010 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 230 DEG/ 03 KTS --- 72 HRS, VALID AT: 050000Z --- 23.8S 112.1E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 000 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 000 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 030 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 090 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 175 DEG/ 06 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 060000Z --- 26.3S 112.3E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 080 NM NORTHEAST QUADRANT 110 NM SOUTHEAST QUADRANT 110 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT VECTOR TO 120 HR POSIT: 170 DEG/ 10 KTS --- 120 HRS, VALID AT: 070000Z --- 30.4S 113.3E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 090 NM NORTHEAST QUADRANT 190 NM SOUTHEAST QUADRANT 150 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT --- REMARKS: 020300Z POSITION NEAR 22.3S 115.8E. 02FEB21. TROPICAL CYCLONE 18S (EIGHTEEN), LOCATED APPROXIMATELY 117 NM EAST OF LEARMONTH, AUSTRALIA, HAS TRACKED SOUTHWESTWARD AT 10 KNOTS OVER THE PAST SIX HOURS. A 12-HR ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS THE SYSTEM MAINTAINED ITS DEEP CONVECTIVE STRUCTURE AS IT TRACKED OVER LAND TOWARD LEARMONTH. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON A LOW LEVEL CIRCULATION (LLC) FEATURE EVIDENT ON AN ABOM COMPOSITE RADAR LOOP THAT ALSO SHOWED ORGANIZED RAIN BANDS WRAPPING INTO THE WELL-DEFINED LLCC. THE INITIAL INTENSITY OF 30 KNOTS 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 CONTINUE ON ITS CURRENT TRACK THROUGH TAU 24 UNDER THE STEERING INFLUENCE OF A LOW- TO MID- LEVEL SUBTROPICAL RIDGE (STR) TO THE SOUTH, PASSING APPROXIMATELY 53NM SOUTH OF LEARMONTH AROUND 021400Z. AFTERWARD, AS THE TC EXITS INTO THE INDIAN OCEAN, THE STORM MOTION WILL BECOME QUASI-STATIONARY (QS) AS A SECONDARY STR BUILDING TO THE SOUTHWEST COMPETES FOR STEERING, RESULTING IN A VERY SLOW WESTWARD TRACK TO TAU 48. AFTER TAU 48, 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 PROMOTE STEADY INTENSIFICATION TO A PEAK OF 50 KNOTS BY TAU 72. AFTERWARD, COOLING SST AND INCREASING VWS WILL GRADUALLY ERODE THE SYSTEM DOWN TO 40KTS BY TAU 120. NUMERICAL MODELS ARE IN FAIRLY GOOD AGREEMENT WITH SPREADING TO OVER 230NM BY TAU 120. THIS, PLUS THE UNCERTAINTY IN THE QS MOTION IN THE MID-PORTION, LENDS AN OVERALL LOW CONFIDENCE TO THE JTWC TRACK FORECAST. NEXT WARNINGS AT 020900Z, 021500Z, 022100Z AND 030300Z.// NNNN