WTXS31 PGTW 022100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 18S (EIGHTEEN) WARNING NR 010// RMKS/ 1. TROPICAL CYCLONE 18S (EIGHTEEN) WARNING NR 010 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 021800Z --- NEAR 24.2S 114.5E MOVEMENT PAST SIX HOURS - 220 DEGREES AT 08 KTS POSITION ACCURATE TO WITHIN 025 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: 24.2S 114.5E --- FORECASTS: 12 HRS, VALID AT: 030600Z --- 24.5S 114.1E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 24 HR POSIT: 285 DEG/ 02 KTS --- 24 HRS, VALID AT: 031800Z --- 24.4S 113.7E 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: 040600Z --- 24.4S 113.3E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 48 HR POSIT: 235 DEG/ 03 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 041800Z --- 24.7S 112.8E 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 000 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 185 DEG/ 04 KTS --- 72 HRS, VALID AT: 051800Z --- 26.2S 112.6E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 000 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 000 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 170 DEG/ 08 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 061800Z --- 29.3S 113.2E 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 - 040 NM NORTHEAST QUADRANT 120 NM SOUTHEAST QUADRANT 090 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT VECTOR TO 120 HR POSIT: 170 DEG/ 08 KTS --- 120 HRS, VALID AT: 071800Z --- 32.6S 113.9E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER --- REMARKS: 022100Z POSITION NEAR 24.3S 114.4E. 02FEB21. TROPICAL CYCLONE 18S (EIGHTEEN), LOCATED APPROXIMATELY 116 NM SOUTH OF LEARMONTH, AUSTRALIA, HAS TRACKED SOUTHWESTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) 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 LOW LEVEL CIRCULATION (LLC) FEATURE EVIDENT ON AN ABOM COMPOSITE RADAR LOOP THAT ALSO SHOWED ORGANIZED RAIN BANDS FROM THE NORTH AND SOUTH 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 12 UNDER THE STEERING INFLUENCE OF A LOW- TO MID-LEVEL SUBTROPICAL RIDGE (STR) TO THE SOUTHEAS. AFTERWARD, 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 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 PROMOTE STEADY INTENSIFICATION TO A PEAK OF 40KTS BY TAU 72. AFTERWARD, COOLING SST AND INCREASING VWS WILL GRADUALLY ERODE THE SYSTEM TO DISSIPATION BY TAU 120. NUMERICAL MODELS ARE IN FAIRLY GOOD AGREEMENT WITH MINIMAL SPREADING; HOWEVER, THE UNCERTAINTY IN THE QS MOTION IN THE MID-PORTION, LENDS AN OVERALL LOW CONFIDENCE TO THE JTWC TRACK FORECAST. NEXT WARNINGS AT 030300Z, 030900Z, 031500Z AND 032100Z.// NNNN