WTPS31 PGTW 080900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE WARNING// RMKS/ 1. TROPICAL CYCLONE 18P (DONNA) WARNING NR 019 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 080600Z --- NEAR 17.5S 165.1E MOVEMENT PAST SIX HOURS - 155 DEGREES AT 07 KTS POSITION ACCURATE TO WITHIN 020 NM POSITION BASED ON EYE FIXED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 115 KT, GUSTS 140 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 055 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 140 NM NORTHEAST QUADRANT 180 NM SOUTHEAST QUADRANT 160 NM SOUTHWEST QUADRANT 110 NM NORTHWEST QUADRANT REPEAT POSIT: 17.5S 165.1E --- FORECASTS: 12 HRS, VALID AT: 081800Z --- 18.8S 165.8E MAX SUSTAINED WINDS - 110 KT, GUSTS 135 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 045 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 045 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 085 NM NORTHEAST QUADRANT 095 NM SOUTHEAST QUADRANT 075 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 165 NM NORTHEAST QUADRANT 195 NM SOUTHEAST QUADRANT 160 NM SOUTHWEST QUADRANT 110 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 155 DEG/ 08 KTS --- 24 HRS, VALID AT: 090600Z --- 20.3S 166.6E MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 015 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 065 NM NORTHEAST QUADRANT 075 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 160 NM NORTHEAST QUADRANT 180 NM SOUTHEAST QUADRANT 125 NM SOUTHWEST QUADRANT 095 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 145 DEG/ 09 KTS --- 36 HRS, VALID AT: 091800Z --- 21.8S 167.7E MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING EXTRATROPICAL RADIUS OF 064 KT WINDS - 020 NM NORTHEAST QUADRANT 025 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 045 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 160 NM NORTHEAST QUADRANT 170 NM SOUTHEAST QUADRANT 105 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 140 DEG/ 12 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 100600Z --- 23.7S 169.3E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING EXTRATROPICAL RADIUS OF 050 KT WINDS - 020 NM NORTHEAST QUADRANT 010 NM SOUTHEAST QUADRANT 015 NM SOUTHWEST QUADRANT 010 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 145 NM NORTHEAST QUADRANT 160 NM SOUTHEAST QUADRANT 085 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 140 DEG/ 15 KTS --- 72 HRS, VALID AT: 110600Z --- 28.2S 174.0E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY EXTRATROPICAL RADIUS OF 034 KT WINDS - 165 NM NORTHEAST QUADRANT 175 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT --- REMARKS: 080900Z POSITION NEAR 17.8S 165.3E. TROPICAL CYCLONE (TC) 18P (DONNA), LOCATED APPROXIMATELY 183 NM WEST OF PORT VILA, VANUATU, HAS TRACKED SOUTH-SOUTHEASTWARD AT 07 KNOTS OVER THE PAST SIX HOURS. AFTER A PERIOD OF RAPID INTENSIFICATION, TC 18P APPEARS TO BE WEAKENING SLIGHTLY WITH THE EYE BECOMING CLOUD- FILLED AND CORE CONVECTION INCREASINGLY ASYMMETRIC. A 080446Z SSMIS 91 GHZ IMAGE INDICATES EROSION OF EYEWALL CONVECTION OVER THE WEST QUADRANT WITH THE BULK OF DEEP CONVECTION NOW OVER THE SOUTHERN SEMI- CIRCLE. TC 18P PEAKED EARLIER NEAR 120 KNOTS BUT IS NOW ASSESSED AT 115 KNOTS BASED ON THE LOWER END OF DVORAK ESTIMATES RANGING FROM 115 TO 127 KNOTS (T6.0 TO 6.5), CONSISTENT WITH THE CONVECTIVE STRUCTURE. TC 18P IS FORECAST TO TRACK SOUTH-SOUTHEASTWARD THROUGH THE FORECAST PERIOD ALONG THE WESTERN PERIPHERY OF A NORTH-SOUTH ORIENTED SUBTROPICAL RIDGE. DYNAMIC GUIDANCE REMAINS IN GOOD AGREEMENT LENDING HIGH CONFIDENCE TO THE FORECAST TRACK. TC DONNA IS EXPECTED TO WEAKEN GRADUALLY AS IT TRACKS EAST OF NEW CALEDONIA DUE TO COOLER SST AND LAND INTERACTION. AFTER TAU 24, THE SYSTEM WILL BEGIN EXTRA-TROPICAL TRANSITION (ETT) AS IT INTERACTS WITH A MAJOR SHORTWAVE TROUGH AND BAROCLINIC ZONE. RAPID WEAKENING IS EXPECTED AFTER TAU 36 DUE TO STRONG VERTICAL WIND SHEAR AND COLD SST. TC 18P SHOULD COMPLETE ETT BY TAU 60. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 080600Z IS 27 FEET. NEXT WARNINGS AT 081500Z, 082100Z, 090300Z AND 090900Z.//