WTXS32 PGTW 240300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 15S (MARCUS) WARNING NR 034// RMKS/ 1. TROPICAL CYCLONE 15S (MARCUS) WARNING NR 034 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 240000Z --- NEAR 25.3S 107.3E MOVEMENT PAST SIX HOURS - 160 DEGREES AT 17 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 085 NM NORTHEAST QUADRANT 080 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 065 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 160 NM NORTHEAST QUADRANT 150 NM SOUTHEAST QUADRANT 130 NM SOUTHWEST QUADRANT 125 NM NORTHWEST QUADRANT REPEAT POSIT: 25.3S 107.3E --- FORECASTS: 12 HRS, VALID AT: 241200Z --- 27.6S 108.0E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 065 NM NORTHEAST QUADRANT 195 NM SOUTHEAST QUADRANT 125 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 160 DEG/ 12 KTS --- 24 HRS, VALID AT: 250000Z --- 29.8S 109.0E 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 - 065 NM NORTHEAST QUADRANT 195 NM SOUTHEAST QUADRANT 125 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 145 DEG/ 12 KTS --- 36 HRS, VALID AT: 251200Z --- 31.8S 110.6E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER --- REMARKS: 240300Z POSITION NEAR 25.9S 107.5E. TROPICAL CYCLONE (TC) 15S (MARCUS), LOCATED APPROXIMATELY 414 NM WEST-SOUTHWEST OF LEARMONTH, AUSTRALIA, HAS TRACKED SOUTH- SOUTHEASTWARD AT 17 KNOTS OVER THE PAST SIX HOURS. ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A RAPIDLY WEAKENING SYSTEM WHICH IS BECOMING INCREASINGLY SHEARED. THE INITIAL POSITION IS ASSESSED BASED ON EXTRAPOLATION OF A 232101Z GPM 36 GHZ MICROWAVE IMAGE WHICH SHOWS THAT THE LLCC HAS BECOME DECOUPLED FROM THE UPPER-LEVEL CONVECTIVE SIGNATURE. ALL DEEP CONVECTION IS NOW LIMITED TO THE SOUTHEASTERN QUADRANT OF THE SYSTEM. THE INITIAL INTENSITY OF 55 KNOTS IS BASED ON A CONSENSUS OF SUBJECTIVE DVORAK CURRENT INTENSITY ESTIMATES OF T4.0 (65 KNOTS) FROM BOTH PGTW AND KNES, AND AUTOMATED INTENSITY ESTIMATES FROM CIMSS OF T3.9. TC 15S IS RAPIDLY WEAKENING AS IT CONTINUES TO TRACK SOUTHEASTWARD ALONG THE WESTERN PERIPHERY OF A DEEP SUBTROPICAL RIDGE OVER WESTERN AUSTRALIA IN A HIGH VWS ENVIRONMENT. THE SYSTEM IS FORECAST TO CONTINUE THIS SOUTHEASTWARD TRACK THROUGH THE DURATION OF THE FORECAST PERIOD UNDER THE INFLUENCE OF THE STEERING RIDGE WHILE CONTINUING TO WEAKEN AS IT PASSES OVER PROGRESSIVELY COOLER WATER AND INTO INCREASING VERTICAL WIND SHEAR. TC MARCUS IS EXPECTED TO DISSIPATE OVER WATER WITHIN THE NEXT 24 TO 36 HOURS. FORECAST MODEL GUIDANCE REMAINS IN STRONG AGREEMENT, LENDING HIGH CONFIDENCE TO THE CURRENT JTWC FORECAST. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 240000Z IS 24 FEET. NEXT WARNINGS AT 240900Z, 241500Z, 242100Z AND 250300Z.//