WTPS51 PGTW 071500 WARNING ATCG MIL 18P SWP 170507130702 2017050712 18P DONNA 016 01 170 09 SATL 020 T000 155S 1648E 095 R064 025 NE QD 025 SE QD 025 SW QD 025 NW QD R050 065 NE QD 065 SE QD 065 SW QD 065 NW QD R034 130 NE QD 190 SE QD 170 SW QD 130 NW QD T012 171S 1650E 100 R064 045 NE QD 045 SE QD 040 SW QD 030 NW QD R050 090 NE QD 085 SE QD 075 SW QD 045 NW QD R034 140 NE QD 215 SE QD 170 SW QD 110 NW QD T024 187S 1655E 095 R064 035 NE QD 040 SE QD 040 SW QD 030 NW QD R050 085 NE QD 075 SE QD 065 SW QD 050 NW QD R034 125 NE QD 205 SE QD 155 SW QD 105 NW QD T036 204S 1665E 085 R064 030 NE QD 030 SE QD 025 SW QD 015 NW QD R050 075 NE QD 070 SE QD 040 SW QD 035 NW QD R034 105 NE QD 180 SE QD 135 SW QD 095 NW QD T048 222S 1678E 070 R064 035 NE QD 020 SE QD 015 SW QD 010 NW QD R050 040 NE QD 025 SE QD 020 SW QD 020 NW QD R034 085 NE QD 155 SE QD 105 SW QD 070 NW QD T072 256S 1712E 040 R034 060 NE QD 125 SE QD 090 SW QD 045 NW QD AMP 036HR BECOMING EXTRATROPICAL 048HR BECOMING EXTRATROPICAL 072HR EXTRATROPICAL SUBJ: TROPICAL CYCLONE 18P (DONNA) WARNING NR 016 1. TROPICAL CYCLONE 18P (DONNA) WARNING NR 016 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 071200Z --- NEAR 15.5S 164.8E MOVEMENT PAST SIX HOURS - 170 DEGREES AT 09 KTS POSITION ACCURATE TO WITHIN 020 NM POSITION BASED ON EYE FIXED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 095 KT, GUSTS 115 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 - 065 NM NORTHEAST QUADRANT 065 NM SOUTHEAST QUADRANT 065 NM SOUTHWEST QUADRANT 065 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 130 NM NORTHEAST QUADRANT 190 NM SOUTHEAST QUADRANT 170 NM SOUTHWEST QUADRANT 130 NM NORTHWEST QUADRANT REPEAT POSIT: 15.5S 164.8E --- FORECASTS: 12 HRS, VALID AT: 080000Z --- 17.1S 165.0E MAX SUSTAINED WINDS - 100 KT, GUSTS 125 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 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 090 NM NORTHEAST QUADRANT 085 NM SOUTHEAST QUADRANT 075 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 140 NM NORTHEAST QUADRANT 215 NM SOUTHEAST QUADRANT 170 NM SOUTHWEST QUADRANT 110 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 165 DEG/ 08 KTS --- 24 HRS, VALID AT: 081200Z --- 18.7S 165.5E MAX SUSTAINED WINDS - 095 KT, GUSTS 115 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 035 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 085 NM NORTHEAST QUADRANT 075 NM SOUTHEAST QUADRANT 065 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 125 NM NORTHEAST QUADRANT 205 NM SOUTHEAST QUADRANT 155 NM SOUTHWEST QUADRANT 105 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 150 DEG/ 10 KTS --- 36 HRS, VALID AT: 090000Z --- 20.4S 166.5E MAX SUSTAINED WINDS - 085 KT, GUSTS 105 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING EXTRATROPICAL RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 015 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 075 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 105 NM NORTHEAST QUADRANT 180 NM SOUTHEAST QUADRANT 135 NM SOUTHWEST QUADRANT 095 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 145 DEG/ 11 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 091200Z --- 22.2S 167.8E 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 020 NM SOUTHEAST QUADRANT 015 NM SOUTHWEST QUADRANT 010 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 025 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 085 NM NORTHEAST QUADRANT 155 NM SOUTHEAST QUADRANT 105 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 140 DEG/ 12 KTS --- 72 HRS, VALID AT: 101200Z --- 25.6S 171.2E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY EXTRATROPICAL RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT 125 NM SOUTHEAST QUADRANT 090 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT --- REMARKS: 071500Z POSITION NEAR 15.9S 164.8E. TROPICAL CYCLONE (TC) 18P (DONNA), LOCATED APPROXIMATELY 241 NM WEST- NORTHWEST OF PORT VILA, VANUATU, HAS TRACKED SOUTHWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS STRENGTHENING, ASYMMETRIC EYEWALL CONVECTION SURROUNDING A 21-NM EYE. A 071052Z METOP-A 89 GHZ IMAGE SHOWS DEEP CONVECTION PRIMARILY OVER THE WESTERN SEMI-CIRCLE AND SHALLOW CONVECTION OVER THE EASTERN SEMI-CIRCLE. UPPER-LEVEL ANALYSIS INDICATES CYCLONIC FLOW OVER THE SYSTEM, WHICH IS LIKELY CONTRIBUTING TO THE PULSATING, ASYMMETRIC CORE CONVECTION, DIVERGING INTO A STRONG POLEWARD OUTFLOW CHANNEL TO THE SOUTHWEST. THE CURRENT INTENSITY IS ASSESSED AT 95 KNOTS BASED ON AN AVERAGE OF DVORAK ESTIMATES RANGING FROM T5.0 TO T5.5. 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 DOMINANT STR. TC DONNA SHOULD CONTINUE TO TRACK SOUTHWARD TO SOUTH-SOUTHEASTWARD THROUGH THE FORECAST PERIOD. DYNAMIC GUIDANCE REMAINS IN GOOD AGREEMENT LENDING HIGH CONFIDENCE TO THE JTWC FORECAST TRACK. TC 18P IS FORECAST TO INTENSIFY SLIGHTLY WITHIN THE NEXT 12 HOURS DUE TO WARM SST AND ROBUST POLEWARD OUTFLOW WITH SOME UNCERTAINTY DUE TO THE COMPLEX UPPER-LEVEL FLOW OVER THE CORE. AFTER TAU 12, GRADUAL WEAKENING SHOULD OCCUR AS THE SYSTEM TRACKS OVER MARGINAL SST. BY TAU 36, 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 071200Z IS 27 FEET. NEXT WARNINGS AT 072100Z, 080300Z, 080900Z AND 081500Z.// 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 90 1817050706 146S1646E 90 1817050706 146S1646E 90 1817050712 155S1648E 95 1817050712 155S1648E 95 1817050712 155S1648E 95 NNNN