WTXS31 PGTW 042100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 18S (EIGHTEEN) WARNING NR 018// RMKS/ 1. TROPICAL CYCLONE 18S (EIGHTEEN) WARNING NR 018 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 041800Z --- NEAR 24.8S 113.1E MOVEMENT PAST SIX HOURS - 235 DEGREES AT 03 KTS POSITION ACCURATE TO WITHIN 040 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING TROPICAL RADIUS OF 034 KT WINDS - 015 NM NORTHEAST QUADRANT 010 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT REPEAT POSIT: 24.8S 113.1E --- FORECASTS: 12 HRS, VALID AT: 050600Z --- 25.3S 112.7E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING SUBTROPICAL RADIUS OF 034 KT WINDS - 000 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 010 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 185 DEG/ 05 KTS --- 24 HRS, VALID AT: 051800Z --- 26.3S 112.6E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING SUBTROPICAL RADIUS OF 034 KT WINDS - 000 NM NORTHEAST QUADRANT 120 NM SOUTHEAST QUADRANT 080 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 175 DEG/ 07 KTS --- 36 HRS, VALID AT: 060600Z --- 27.7S 112.8E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY SUBTROPICAL RADIUS OF 034 KT WINDS - 020 NM NORTHEAST QUADRANT 130 NM SOUTHEAST QUADRANT 110 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT --- REMARKS: 042100Z POSITION NEAR 24.9S 113.0E. 04FEB21. TROPICAL CYCLONE (TC) 18S (EIGHTEEN), LOCATED APPROXIMATELY 160 NM SOUTH-SOUTHWEST OF LEARMONTH, AUSTRALIA, HAS TRACKED SOUTHWESTWARD AT 03 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS FLARING DEEP CONVECTION EAST OF A DEFINED LOW-LEVEL CIRCULATION CENTER, WHICH SUPPORTS THE INITIAL POSITION WITH FAIR CONFIDENCE. THE CENTER IS LOCATED APPROXIMATELY 34NM WEST OF CARNARVON, WHICH IS REPORTING SUSTAINED SURFACE WINDS (10-MINUTE AVERAGE) OF 24 KNOTS AND A MSLP OF 996MB, WHICH TYPICALLY CORRESPONDS TO A 35-40 KNOT TROPICAL CYCLONE. A 041354Z ASCAT-C IMAGE REVEALS AN EXTENSIVE SWATH OF 30-35 KNOT WINDS OVER WATER TO THE SOUTHWEST ASSOCIATED WITH A LARGE FIELD OF STABLE, COOL-AIR STRATOCUMULUS AS EVIDENT IN EIR. OVERALL, THIS DATA SUPPORTS THE INITIAL INTENSITY ASSESSMENT OF 35 KNOTS. ANALYSIS INDICATES UNFAVORABLE CONDITIONS WITH HIGH (20-25 KNOTS) WIND SHEAR (VWS), SPEED DIVERGENCE INTO THE WESTERLIES OFFSET TO THE SOUTH, AND MARGINAL SST VALUES (25-26C). TC 18S WILL CONTINUE SOUTHWARD AS A STR BUILDS EAST OF THE SYSTEM OVER WESTERN AUSTRALIA. DUE TO THE SOUTHWARD TRACK, THE SYSTEM WILL MOVE UNDER THE SUBTROPICAL WESTERLIES WITH INCREASING VWS (30-45 KNOTS). TC 18S IS EXPECTED TO SLIGHTLY INTENSIFY AND GRADUALLY TRANSITION INTO A SUBTROPICAL CYCLONE. NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT LENDING HIGH CONFIDENCE TO THE JTWC FORECAST TRACK, WHICH IS POSITIONED NEAR THE MULTI-MODEL CONSENSUS. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 041800Z IS 15 FEET. NEXT WARNINGS AT 050300Z, 050900Z, 051500Z AND 052100Z. // NNNN