WTPS31 PGTW 072100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 18P (DONNA) WARNING NR 017// RMKS/ 1. TROPICAL CYCLONE 18P (DONNA) WARNING NR 017 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 071800Z --- NEAR 16.5S 164.8E MOVEMENT PAST SIX HOURS - 180 DEGREES AT 10 KTS POSITION ACCURATE TO WITHIN 030 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 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 070 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 075 NM SOUTHWEST QUADRANT 075 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 145 NM NORTHEAST QUADRANT 180 NM SOUTHEAST QUADRANT 160 NM SOUTHWEST QUADRANT 140 NM NORTHWEST QUADRANT REPEAT POSIT: 16.5S 164.8E --- FORECASTS: 12 HRS, VALID AT: 080600Z --- 18.2S 165.3E 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 040 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 085 NM NORTHEAST QUADRANT 095 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 170 NM NORTHEAST QUADRANT 180 NM SOUTHEAST QUADRANT 140 NM SOUTHWEST QUADRANT 115 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 160 DEG/ 09 KTS --- 24 HRS, VALID AT: 081800Z --- 19.9S 166.0E MAX SUSTAINED WINDS - 100 KT, GUSTS 125 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 075 NM NORTHEAST QUADRANT 075 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 165 NM NORTHEAST QUADRANT 170 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 155 DEG/ 09 KTS --- 36 HRS, VALID AT: 090600Z --- 21.6S 166.9E MAX SUSTAINED WINDS - 080 KT, GUSTS 100 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING EXTRATROPICAL RADIUS OF 064 KT WINDS - 015 NM NORTHEAST QUADRANT 015 NM SOUTHEAST QUADRANT 015 NM SOUTHWEST QUADRANT 015 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 045 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 165 NM NORTHEAST QUADRANT 170 NM SOUTHEAST QUADRANT 090 NM SOUTHWEST QUADRANT 085 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 140 DEG/ 10 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 091800Z --- 23.1S 168.3E MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING EXTRATROPICAL RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 025 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 160 NM NORTHEAST QUADRANT 175 NM SOUTHEAST QUADRANT 090 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 140 DEG/ 13 KTS --- 72 HRS, VALID AT: 101800Z --- 26.8S 172.1E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY EXTRATROPICAL RADIUS OF 034 KT WINDS - 120 NM NORTHEAST QUADRANT 190 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT --- REMARKS: 072100Z POSITION NEAR 16.9S 164.9E. TROPICAL CYCLONE 18P (DONNA), LOCATED APPROXIMATELY 213 NM WEST- NORTHWEST OF PORT VILA, VANUATU, HAS TRACKED SOUTHWARD AT 10 KNOTS OVER THE PAST SIX HOURS. AFTER DAYS OF SLOW OR STALLED DEVELOPMENT, ANIMATED ENHANCED INFRARED SATELLITE IMAGERY INDICATES TC 18P HAS IMPROVED ITS OVERALL CONVECTIVE ORGANIZATION AND MAINTAINED A RAGGED 25 NM DIAMETER EYE DURING A PERIOD OF PRONOUNCED INTENSIFICATION. THE INITIAL POSITION IS BASED ON EYE FIXES WITH HIGH CONFIDENCE. THE INITIAL INTENSITY IS ASSESSED AT 115 KNOTS BASED ON DVORAK INTENSITY ESTIMATES OF T6.0 (115 KNOTS) FROM KNES AND NFFN. THE PGTW DVORAK ESTIMATE IS T6.5, HOWEVER, AN ASSESSMENT OF RECENT 89 GHZ MICROWAVE IMAGERY DOES NOT SUPPORT THAT RANGE AT THIS TIME. TC DONNA IS CURRENTLY TRACKING SOUTH-SOUTHEASTWARD UNDER THE INFLUENCE OF A WELL-ESTABLISHED SUB-TROPICAL RIDGE TO THE EAST. THIS MOTION IS EXPECTED TO CONTINUE OVER THE NEXT 36 HOURS BEFORE BECOMING MORE SOUTHEASTWARD LATER IN THE FORECAST PERIOD IN RESPONSE TO AN APPROACHING SHORTWAVE TROUGH. DYNAMIC GUIDANCE REMAINS IN GOOD AGREEMENT LENDING HIGH CONFIDENCE TO THE JTWC FORECAST TRACK. ENVIRONMENTAL CONDITIONS, INCLUDING LIGHT VERTICAL WIND SHEAR (VWS), ROBUST POLEWARD OUTFLOW, AND WARM SST WATERS WILL PERSIST OVER THE NEXT 12 HOURS ALLOWING THE SYSTEM TO REMAIN NEAR ITS CURRENT INTENSITY. BETWEEN TAUS 24 TO 36, SSTS WILL BEGIN TO FALL AND LAND INTERACTION WITH NEW CALEDONIA WILL INCREASE, INITIATING A SLOW DISSIPATION. BY TAU 36, TC 18P WILL BEGIN EXTRA-TROPICAL TRANSITION AND RAPIDLY WEAKEN AS IT MOVES OVER SUB-26 DEGREE CELSIUS WATER AND INTERACTS WITH MIDLATITUDE WESTERLIES AND THE WEAK BAROCLINIC ZONE. THE SYSTEM IS EXPECTED TO COMPLETE EXTRA-TROPICAL TRANSITION AT THE END OF THE FORECAST AS IT BECOMES EMBEDDED WITHIN THE MIDLATITUDE WESTERLIES. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 071800Z IS 32 FEET. NEXT WARNINGS AT 080300Z, 080900Z, 081500Z AND 082100Z. //