WTXS31 PGTW 020900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 18S (EIGHTEEN) WARNING NR 008// RMKS/ 1. TROPICAL CYCLONE 18S (EIGHTEEN) WARNING NR 008 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 020600Z --- NEAR 22.9S 115.7E MOVEMENT PAST SIX HOURS - 220 DEGREES AT 09 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: 22.9S 115.7E --- FORECASTS: 12 HRS, VALID AT: 021800Z --- 23.9S 114.8E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 24 HR POSIT: 255 DEG/ 02 KTS --- 24 HRS, VALID AT: 030600Z --- 24.0S 114.4E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 36 HR POSIT: 270 DEG/ 01 KTS --- 36 HRS, VALID AT: 031800Z --- 24.0S 114.2E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 48 HR POSIT: 260 DEG/ 02 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 040600Z --- 24.1S 113.7E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 72 HR POSIT: 235 DEG/ 03 KTS --- 72 HRS, VALID AT: 050600Z --- 24.7S 112.7E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 180 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 110 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 175 DEG/ 07 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 060600Z --- 27.3S 113.0E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT 140 NM SOUTHEAST QUADRANT 120 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT VECTOR TO 120 HR POSIT: 165 DEG/ 09 KTS --- 120 HRS, VALID AT: 070600Z --- 30.7S 113.9E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT 210 NM SOUTHEAST QUADRANT 170 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT --- REMARKS: 020900Z POSITION NEAR 23.2S 115.5E. 02FEB21. TROPICAL CYCLONE (TC) 18S (EIGHTEEN), LOCATED APPROXIMATELY 96 NM EAST-SOUTHEAST OF LEARMONTH, AUSTRALIA, HAS TRACKED SOUTHWESTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS SPIRAL BANDS OF DEEP CONVECTION THAT WRAP INTO AN OBSCURED LOW LEVEL CIRCULATION CENTER (LLCC). THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON IMAGERY FROM A 020633Z ATMS PASS, MULTIPLE SURFACE OBSERVATIONS AND THE OVERALL STRUCTURE OF THE SYSTEM NOTED IN THE COMPOSITE RADAR LOOP FROM DAMPIER, AUSTRALIA. THE INITIAL INTENSITY IS ASSESSED AT 30 KTS BASED ON THE AFOREMENTIONED SURFACE OBSERVATIONS WITH FAIR CONFIDENCE. TC 18S IS TRACKING ALONG THE SOUTHERN PERIPHERY OF A LOW TO MID LEVEL SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTH. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM HAS ROBUST RADIAL OUTFLOW AND IS TRACKING THROUGH A REGION OF LOW (5-10 KTS) VERTICAL WIND SHEAR. THE SYSTEM WILL CONTINUE ITS GENERALLY WESTWARD TRACK UNDER THE STEERING INFLUENCE OF THE STR THROUGH TAU 24 AT WHICH TIME IT WILL BE APPROXIMATELY 110 NM SOUTH OF LEARMONTH. THEREAFTER, THE SYSTEM WILL ENTER A COMPETITIVE STEERING ENVIRONMENT AS A STR POSITIONED TO THE SOUTHWEST BUILDS. THIS WILL LEAD TO A TEMPORARY, QUASI- STATIONARY MOTION THROUGH TAU 36. AFTER TAU 48, TC 18S WILL ENTER THE WARM (27-28 CELSIUS) WATERS OF THE INDIAN OCEAN AND INTENSIFY SLIGHTLY TO 45 KTS BY TAU 72. THEREAFTER, THE STR POSITIONED TO THE SOUTHWEST WILL BECOME THE PREDOMINANT STEERING MECHANISM AND BEGIN TO DRIVE THE SYSTEM ON A SOUTH TO SOUTH-SOUTHEASTWARD TRACK FOR THE REMAINDER OF THE FORECAST PERIOD. INCREASING VWS AND COOLING SST AFTER TAU 96 WILL LEAD TO A GRADUAL WEAKENING TO 35 KTS BY TAU 120. NUMERICAL MODEL GUIDANCE IS IN OVERALL FAIR AGREEMENT AS MODELS STRUGGLE TO RESOLVE THE TIMING OF THE CHANGE IN THE OVERALL STEERING ENVIRONMENT AND LENDS OVERALL FAIR CONFIDENCE IN THE JTWC FORECAST TRACK WHICH IS PLACED ON THE MULTI-MODEL CONSENSUS. NEXT WARNINGS AT 021500Z, 022100Z, 030300Z AND 030900Z.// NNNN