WTXS31 PGTW 011500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 18S (EIGHTEEN) WARNING NR 005// RMKS/ 1. TROPICAL CYCLONE 18S (EIGHTEEN) WARNING NR 005 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 011200Z --- NEAR 21.1S 118.1E MOVEMENT PAST SIX HOURS - 240 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: 21.1S 118.1E --- FORECASTS: 12 HRS, VALID AT: 020000Z --- 21.8S 116.2E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 24 HR POSIT: 245 DEG/ 07 KTS --- 24 HRS, VALID AT: 021200Z --- 22.4S 114.8E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 36 HR POSIT: 260 DEG/ 05 KTS --- 36 HRS, VALID AT: 030000Z --- 22.6S 113.7E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 280 DEG/ 03 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 031200Z --- 22.5S 113.0E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 270 DEG/ 02 KTS --- 72 HRS, VALID AT: 041200Z --- 22.5S 112.2E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 000 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 000 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 030 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 185 DEG/ 04 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 051200Z --- 24.0S 112.1E MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 000 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 000 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT 130 NM SOUTHEAST QUADRANT 120 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT VECTOR TO 120 HR POSIT: 170 DEG/ 05 KTS --- 120 HRS, VALID AT: 061200Z --- 26.1S 112.5E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 000 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT 190 NM SOUTHEAST QUADRANT 160 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT --- REMARKS: 011500Z POSITION NEAR 21.3S 117.6E. 01FEB21. TROPICAL CYCLONE (TC) 18S (EIGHTEEN), LOCATED APPROXIMATELY 56 NM SOUTH-SOUTHWEST OF PORT HEDLAND, AUSTRALIA, HAS TRACKED WEST- SOUTHWESTWARD AT 10 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY AND A 011100Z SSMIS 91GHZ DEPICT FRAGMENTED CONVECTIVE BANDING WRAPPING INTO A DEFINED LOW-LEVEL CIRCULATION CENTER. ANIMATED RADAR IMAGERY FROM THE PORT HEDLAND RADAR INDICATES A WELL-ORGANIZED SYSTEM WITH MULTIPLE CONVECTIVE BANDS WRAPPING INTO THE WELL-DEFINED CENTER. THUS, THERE IS HIGH CONFIDENCE IN THE INITIAL POSITION AND RECENT TRACK MOTION. THE INITIAL INTENSITY REMAINS ASSESSED AT 30 KNOTS BASED ON THE CONVECTIVE STRUCTURE AND SURFACE OBSERVATIONS FROM PORT HEDLAND, WHICH IS REPORTING GUSTS OF 20-25 KNOTS WITH A SLP VALUE OF 997MB. UPPER-LEVEL ANALYSIS INDICATES NEAR-RADIAL OUTFLOW AND LOW VERTICAL WIND SHEAR. TC 18S IS FORECAST TO TRACK WEST-SOUTHWESTWARD THROUGH TAU 24 UNDER THE STEERING INFLUENCE OF A LOW- TO MID-LEVEL SUBTROPICAL RIDGE (STR) POSITIONED OVER SOUTHWESTERN AUSTRALIA. AFTER TAU 24, THE STEERING PATTERN IS EXPECTED TO BECOME MORE COMPLEX WITH ANOTHER STR BUILDING WEST OF THE SYSTEM. CONSEQUENTLY, TC 18S SHOULD SLOW SIGNIFICANTLY UNTIL A BROAD TROUGH FORMS WEST OF AUSTRALIA, WHICH SHOULD DRIVE THE SYSTEM SLOWLY SOUTHWARD AFTER TAU 72. NUMERICAL MODEL GUIDANCE SUPPORTS THIS SCENARIO WITH FAIR CONFIDENCE AND WHILE ALL TRACKERS DEPICT THE SOUTHWARD TURN THERE ARE MAJOR DIFFERENCES IN THE TIMING AND LOCATION OF THIS SOUTHWARD TURN. DUE TO THIS COMPLEX, EVOLVING STEERING PATTERN, THERE IS MODERATE CONFIDENCE IN THE OVERALL JTWC FORECAST TRACK. TC 18S IS EXPECTED TO MAINTAIN INTENSITY WHILE IT TRACKS OVER LAND ALONG THE COAST BUT WILL INTENSIFY TO 35 KNOTS AS IT APPROACHES THE EXMOUTH PENINSULA AND LEARMONTH SOLAR OBSERVATORY. AFTER TAU 36, THE SYSTEM SHOULD GRADUALLY INTENSIFY TO A PEAK INTENSITY OF 55 KNOTS BY TAU 96 WITH FAVORABLE ENVIRONMENTAL CONDITIONS AND WARM SST. NEXT WARNINGS AT 012100Z, 020300Z, 020900Z AND 021500Z.// NNNN