WTPS51 PGTW 070900 WARNING ATCG MIL 18P SWP 170507073132 2017050706 18P DONNA 015 01 150 08 SATL 015 T000 146S 1646E 085 R064 025 NE QD 025 SE QD 025 SW QD 025 NW QD R050 060 NE QD 060 SE QD 065 SW QD 065 NW QD R034 160 NE QD 155 SE QD 160 SW QD 125 NW QD T012 163S 1649E 095 R064 055 NE QD 055 SE QD 045 SW QD 045 NW QD R050 095 NE QD 100 SE QD 075 SW QD 065 NW QD R034 190 NE QD 200 SE QD 175 SW QD 125 NW QD T024 178S 1653E 100 R064 055 NE QD 060 SE QD 050 SW QD 035 NW QD R050 095 NE QD 110 SE QD 080 SW QD 060 NW QD R034 190 NE QD 215 SE QD 170 SW QD 110 NW QD T036 194S 1660E 085 R064 045 NE QD 050 SE QD 045 SW QD 030 NW QD R050 085 NE QD 095 SE QD 075 SW QD 055 NW QD R034 165 NE QD 210 SE QD 150 SW QD 100 NW QD T048 211S 1672E 070 R064 035 NE QD 040 SE QD 035 SW QD 025 NW QD R050 065 NE QD 070 SE QD 055 SW QD 040 NW QD R034 160 NE QD 180 SE QD 130 SW QD 095 NW QD T072 247S 1704E 040 R034 135 NE QD 180 SE QD 080 SW QD 060 NW QD AMP 048HR BECOMING EXTRATROPICAL 072HR EXTRATROPICAL SUBJ: TROPICAL CYCLONE 18P (DONNA) WARNING NR 015 1. TROPICAL CYCLONE 18P (DONNA) WARNING NR 015 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 070600Z --- NEAR 14.6S 164.6E MOVEMENT PAST SIX HOURS - 150 DEGREES AT 08 KTS POSITION ACCURATE TO WITHIN 015 NM POSITION BASED ON EYE FIXED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 085 KT, GUSTS 105 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 025 NM NORTHEAST QUADRANT 025 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 065 NM SOUTHWEST QUADRANT 065 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 160 NM NORTHEAST QUADRANT 155 NM SOUTHEAST QUADRANT 160 NM SOUTHWEST QUADRANT 125 NM NORTHWEST QUADRANT REPEAT POSIT: 14.6S 164.6E --- FORECASTS: 12 HRS, VALID AT: 071800Z --- 16.3S 164.9E MAX SUSTAINED WINDS - 095 KT, GUSTS 115 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 055 NM NORTHEAST QUADRANT 055 NM SOUTHEAST QUADRANT 045 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 095 NM NORTHEAST QUADRANT 100 NM SOUTHEAST QUADRANT 075 NM SOUTHWEST QUADRANT 065 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 190 NM NORTHEAST QUADRANT 200 NM SOUTHEAST QUADRANT 175 NM SOUTHWEST QUADRANT 125 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 165 DEG/ 08 KTS --- 24 HRS, VALID AT: 080600Z --- 17.8S 165.3E MAX SUSTAINED WINDS - 100 KT, GUSTS 125 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 055 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 095 NM NORTHEAST QUADRANT 110 NM SOUTHEAST QUADRANT 080 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 190 NM NORTHEAST QUADRANT 215 NM SOUTHEAST QUADRANT 170 NM SOUTHWEST QUADRANT 110 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 160 DEG/ 09 KTS --- 36 HRS, VALID AT: 081800Z --- 19.4S 166.0E MAX SUSTAINED WINDS - 085 KT, GUSTS 105 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 045 NM NORTHEAST QUADRANT 050 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 210 NM SOUTHEAST QUADRANT 150 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 145 DEG/ 10 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 090600Z --- 21.1S 167.2E MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING EXTRATROPICAL RADIUS OF 064 KT WINDS - 035 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 065 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 160 NM NORTHEAST QUADRANT 180 NM SOUTHEAST QUADRANT 130 NM SOUTHWEST QUADRANT 095 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 140 DEG/ 12 KTS --- 72 HRS, VALID AT: 100600Z --- 24.7S 170.4E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY EXTRATROPICAL RADIUS OF 034 KT WINDS - 135 NM NORTHEAST QUADRANT 180 NM SOUTHEAST QUADRANT 080 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT --- REMARKS: 070900Z POSITION NEAR 15.0S 164.7E. TROPICAL CYCLONE (TC) 18P (DONNA), LOCATED APPROXIMATELY 283 NM NORTHWEST OF PORT VILA, VANUATU, HAS TRACKED SOUTH-SOUTHEASTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS IMPROVED CONVECTIVE ORGANIZATION WITH A 17- NM EYE EVIDENT, HOWEVER, DEEP CONVECTION CONTINUES TO CYCLE RAPIDLY. A 070500Z SSMIS 91 GHZ IMAGE SHOWS ASYMMETRIC CORE CONVECTION WITH A DEEP CONVECTIVE BAND OVER THE WESTERN SEMI-CIRCLE AND SHALLOW BANDING OVER THE EASTERN SEMI-CIRCLE OF THE EYEWALL. UPPER-LEVEL ANALYSIS INDICATES CYCLONIC FLOW OVER THE CORE, WHICH IS LIKELY CONTRIBUTING TO THE FLAT TREND AND PULSATING CONVECTION, DIVERGING INTO A STRONG POLEWARD OUTFLOW CHANNEL TO THE SOUTHWEST. THE CURRENT INTENSITY REMAINS ASSESSED AT 85 KNOTS BASED ON AN AVERAGE OF 4.5/5.0 DVORAK ESTIMATES FROM PGTW, KNES AND PHFO. CURRENT MODEL ANALYSES INDICATE THAT THE WESTERN SUBTROPICAL RIDGE (STR) HAS ERODED DUE TO AN APPROACHING MAJOR SHORTWAVE TROUGH, THEREFORE, THE EASTERN STR IS NOW THE DOMINANT STEERING RIDGE. CONSEQUENTLY, TC 18P HAS ACCELERATED SOUTHWARD AS IT TRACKS ALONG THE WESTERN PERIPHERY OF THE STR. TC DONNA SHOULD CONTINUE TO TRACK SOUTHWARD TO SOUTH- SOUTHEASTWARD THROUGH THE FORECAST PERIOD. DYNAMIC GUIDANCE REMAINS IN TIGHT AGREEMENT LENDING HIGH CONFIDENCE TO THE JTWC FORECAST TRACK. TC 18P IS FORECAST TO INTENSIFY SLIGHTLY WITHIN THE NEXT 24 HOURS DUE TO WARM SST AND ROBUST POLEWARD OUTFLOW WITH SOME UNCERTAINTY DUE TO THE COMPLEX UPPER-LEVEL FLOW OVER THE CORE. AFTER TAU 24, GRADUAL WEAKENING SHOULD OCCUR AS THE SYSTEM TRACKS OVER MARGINAL SST. BY TAU 48, TC 18P WILL BEGIN EXTRA-TROPICAL TRANSITION AND RAPIDLY WEAKEN AS IT INTERACTS WITH THE MIDLATITUDE WESTERLIES AND THE WEAK BAROCLINIC ZONE. THE SYSTEM IS EXPECTED TO COMPLETE EXTRA-TROPICAL TRANSITION AS IT BECOMES EMBEDDED WITHIN THE MIDLATITUDE WESTERLIES. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 070600Z IS 24 FEET. NEXT WARNINGS AT 071500Z, 072100Z, 080300Z AND 080900Z.// 1817042906 105S1604E 15 1817042912 108S1612E 15 1817042918 110S1620E 15 1817043000 112S1629E 15 1817043006 113S1637E 15 1817043012 116S1644E 15 1817043018 118S1654E 15 1817050100 119S1676E 15 1817050106 121S1692E 20 1817050112 126S1696E 25 1817050118 127S1702E 30 1817050200 128S1707E 30 1817050206 129S1707E 30 1817050212 130S1712E 30 1817050218 130S1714E 40 1817050300 128S1717E 50 1817050306 127S1712E 55 1817050306 127S1712E 55 1817050312 128S1705E 55 1817050312 128S1705E 55 1817050318 128S1696E 65 1817050318 128S1696E 65 1817050318 128S1696E 65 1817050400 125S1686E 75 1817050400 125S1686E 75 1817050400 125S1686E 75 1817050406 125S1681E 80 1817050406 125S1681E 80 1817050406 125S1681E 80 1817050412 126S1676E 85 1817050412 126S1676E 85 1817050412 126S1676E 85 1817050418 129S1668E 85 1817050418 129S1668E 85 1817050418 129S1668E 85 1817050500 130S1662E 85 1817050500 130S1662E 85 1817050500 130S1662E 85 1817050506 134S1656E 90 1817050506 134S1656E 90 1817050506 134S1656E 90 1817050512 137S1649E 90 1817050512 137S1649E 90 1817050512 137S1649E 90 1817050515 135S1646E 90 1817050515 135S1646E 90 1817050515 135S1646E 90 1817050518 133S1645E 90 1817050518 133S1645E 90 1817050518 133S1645E 90 1817050600 132S1643E 85 1817050600 132S1643E 85 1817050600 132S1643E 85 1817050606 133S1642E 85 1817050606 133S1642E 85 1817050606 133S1642E 85 1817050612 132S1641E 90 1817050612 132S1641E 90 1817050612 132S1641E 90 1817050618 134S1641E 90 1817050618 134S1641E 90 1817050618 134S1641E 90 1817050700 139S1642E 85 1817050700 139S1642E 85 1817050700 139S1642E 85 1817050706 146S1646E 85 1817050706 146S1646E 85 1817050706 146S1646E 85 NNNN