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: 021200Z --- NEAR 23.6S 115.1E 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: 23.6S 115.1E --- FORECASTS: 12 HRS, VALID AT: 030000Z --- 24.2S 114.4E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 24 HR POSIT: 270 DEG/ 01 KTS --- 24 HRS, VALID AT: 031200Z --- 24.2S 114.2E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 36 HR POSIT: 305 DEG/ 02 KTS --- 36 HRS, VALID AT: 040000Z --- 24.0S 113.9E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 48 HR POSIT: 250 DEG/ 03 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 041200Z --- 24.2S 113.3E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 72 HR POSIT: 220 DEG/ 03 KTS --- 72 HRS, VALID AT: 051200Z --- 25.0S 112.6E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 160 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 140 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 170 DEG/ 08 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 061200Z --- 28.2S 113.1E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT 130 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT VECTOR TO 120 HR POSIT: 170 DEG/ 08 KTS --- 120 HRS, VALID AT: 071200Z --- 31.4S 113.9E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT 140 NM SOUTHEAST QUADRANT 110 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT --- REMARKS: 021500Z POSITION NEAR 23.8S 114.9E. 02FEB21. TROPICAL CYCLONE (TC) 18S (EIGHTEEN), LOCATED APPROXIMATELY 96 NM SOUTHEAST OF LEARMONTH, AUSTRALIA, HAS TRACKED SOUTHWESTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY 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 021046Z SSMIS 91 GHZ IMAGE, MULTIPLE SURFACE OBSERVATIONS AND THE OVERALL MOTION OF THE RAIN BANDS DEPICTED 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 NORTHWESTERN PERIPHERY OF A SUBTROPICAL RIDGE POSITIONED TO THE SOUTH- EAST. 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 TO SOUTHWESTWARD TRACK UNDER THE STEERING INFLUENCE OF THE STR THROUGH TAU 24 AT WHICH TIME IT WILL BE APPROXIMATELY 125 NM SOUTH OF LEARMONTH. THEREAFTER, A HIGH AMPLITUDE TROUGH PROPAGATING FROM THE SOUTHWEST WILL LEAD TO AN EROSION AND SUBSEQUENT REPOSITIONING OF THE STEERING STR. DURING THIS TIME, THE SYSTEM WILL ENTER A WEAK STEERING ENVIRONMENT AS THE STR RE-POSITIONS AND WILL UNDERGO A TEMPORARY, QUASISTATIONARY MOTION THROUGH TAU 36 AS A RESULT. 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. AS THE STEERING RIDGE BUILDS, IT WILL DRIVE TC 18S POLEWARD THROUGHOUT THE REMAINDER OF THE FORECAST PERIOD. INCREASING VWS AFTER TAU 48, AND COOLER SST (<26 CELSIUS) 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 STEERING ENVIRONMENT AND THUS LENDS OVERALL FAIR CONFIDENCE IN THE JTWC FORECAST TRACK WHICH IS PLACED ON THE MULTI- MODEL CONSENSUS. NEXT WARNINGS AT 022100Z, 030300Z, 030900Z AND 031500Z. // NNNN