WTPS32 PGTW 210900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 18P (NATHAN) WARNING NR 022// RMKS/ 1. TROPICAL CYCLONE 18P (NATHAN) WARNING NR 022 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 210600Z --- NEAR 13.7S 139.3E MOVEMENT PAST SIX HOURS - 270 DEGREES AT 10 KTS POSITION ACCURATE TO WITHIN 035 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 065 NM NORTHEAST QUADRANT 065 NM SOUTHEAST QUADRANT 075 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT REPEAT POSIT: 13.7S 139.3E --- FORECASTS: 12 HRS, VALID AT: 211800Z --- 13.0S 137.5E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 075 NM NORTHEAST QUADRANT 075 NM SOUTHEAST QUADRANT 085 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 295 DEG/ 09 KTS --- 24 HRS, VALID AT: 220600Z --- 12.2S 135.8E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 36 HR POSIT: 295 DEG/ 07 KTS --- 36 HRS, VALID AT: 221800Z --- 11.6S 134.6E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 065 NM NORTHEAST QUADRANT 065 NM SOUTHEAST QUADRANT 075 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 285 DEG/ 05 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 230600Z --- 11.4S 133.7E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 075 NM NORTHEAST QUADRANT 075 NM SOUTHEAST QUADRANT 085 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 250 DEG/ 03 KTS --- 72 HRS, VALID AT: 240600Z --- 11.8S 132.7E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 96 HR POSIT: 230 DEG/ 04 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 250600Z --- 12.7S 131.6E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND VECTOR TO 120 HR POSIT: 235 DEG/ 04 KTS --- 120 HRS, VALID AT: 260600Z --- 13.6S 130.3E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND --- REMARKS: 210900Z POSITION NEAR 13.5S 138.8E. TROPICAL CYCLONE (TC) 18P (NATHAN), LOCATED APPROXIMATELY 496 NM EAST OF DARWIN, AUSTRALIA, HAS TRACKED WESTWARD AT 10 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THE SYSTEM HAS MAINTAINED OVERALL CONVECTIVE STRENGTH AS IT DRIFTED ACROSS THE GULF OF CARPENTARIA. THE INITIAL POSITION IS BASED ON THE MSI AND A COMPOSITE RADAR LOOP FROM GOVE AIRPORT WITH FAIR CONFIDENCE. THE INITIAL INTENSITY IS BASED ON AN OVERALL ASSESSMENT OF DVORAK ESTIMATES FROM PGTW, KNES, AND ADRM. UPPER-LEVEL ANALYSIS INDICATES TC 18P REMAINS IN A FAVORABLE ENVIRONMENT WITH A POINT-SOURCE ANTICYCLONE DIRECTLY OVERHEAD THAT IS ENHANCING OUTFLOW, AND LOW (05 TO 10 KNOT) VERTICAL WIND SHEAR. THE CYCLONE IS TRACKING ALONG THE NORTHERN PERIPHERY OF A DEEP LAYERED SUB-TROPICAL RIDGE TO THE SOUTH, OVER CENTRAL AUSTRALIA. IT IS EXPECTED TO DRAG ACROSS THE COASTLINE OF THE NORTHERN TERRITORY PRIOR TO DIPPING INLAND BEFORE DARWIN AND DISSIPATE BY TAU 120. AVAILABLE MODEL GUIDANCE IS IN OVERALL GOOD AGREEMENT LENDING HIGH CONFIDENCE IN THE JTWC TRACK FORECAST. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 210600Z IS 13 FEET. NEXT WARNINGS AT 212100Z AND 220900Z.//