WTXS31 PGTW 230900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 18P (NATHAN) WARNING NR 026// RMKS/ 1. TROPICAL CYCLONE 18P (NATHAN) WARNING NR 026 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 230600Z --- NEAR 11.4S 134.3E MOVEMENT PAST SIX HOURS - 280 DEGREES AT 06 KTS POSITION ACCURATE TO WITHIN 035 NM POSITION BASED ON CENTER LOCATED BY A COMBINATION OF SATELLITE AND RADAR PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 025 NM NORTHEAST QUADRANT 025 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 055 NM NORTHEAST QUADRANT 055 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 065 NM NORTHWEST QUADRANT REPEAT POSIT: 11.4S 134.3E --- FORECASTS: 12 HRS, VALID AT: 231800Z --- 11.5S 133.6E MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 015 NM NORTHEAST QUADRANT 015 NM SOUTHEAST QUADRANT 015 NM SOUTHWEST QUADRANT 015 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 055 NM NORTHEAST QUADRANT 055 NM SOUTHEAST QUADRANT 065 NM SOUTHWEST QUADRANT 065 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 235 DEG/ 04 KTS --- 24 HRS, VALID AT: 240600Z --- 11.9S 133.0E MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 36 HR POSIT: 235 DEG/ 04 KTS --- 36 HRS, VALID AT: 241800Z --- 12.4S 132.3E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 48 HR POSIT: 255 DEG/ 05 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 250600Z --- 12.7S 131.3E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 72 HR POSIT: 260 DEG/ 06 KTS --- 72 HRS, VALID AT: 260600Z --- 13.0S 128.9E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 96 HR POSIT: 270 DEG/ 07 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 270600Z --- 13.0S 125.9E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 120 HR POSIT: 265 DEG/ 08 KTS --- 120 HRS, VALID AT: 280600Z --- 13.3S 122.5E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY --- REMARKS: 230900Z POSITION NEAR 11.4S 134.1E. TROPICAL CYCLONE (TC) 18P (NATHAN), LOCATED APPROXIMATELY 210 NM EAST-NORTHEAST OF DARWIN, AUSTRALIA, HAS TRACKED WESTWARD AT 06 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS THE SYSTEM HAS MAINTAINED OVERALL CONVECTIVE SIGNATURE AS IT DRIFTED JUST OFFSHORE OF THE NORTHERN TERRITORY. THE INITIAL POSITION IS BASED ON A COMPOSITE RADAR LOOP FROM GOVE AIRPORT WITH GOOD CONFIDENCE. THE INITIAL INTENSITY IS BASED ON AN OVERALL ASSESSMENT OF DVORAK ESTIMATES FROM PGTW, ADRM, AND KNES. UPPER- LEVEL ANALYSIS INDICATES TC NATHAN REMAINS IN A FAVORABLE ENVIRONMENT WITH A POINT-SOURCE ANTICYCLONE DIRECTLY OVERHEAD THAT IS PROVIDING RADIAL OUTFLOW. TC 18P IS TRACKING ALONG THE NORTHERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE SOUTH, OVER CENTRAL AUSTRALIA. AFTER TAU 12, THE STR WILL WEAKEN SLIGHTLY WITH THE APPROACH OF A MIGRATORY MID-LATITUDE TROUGH FROM THE SOUTHWEST. THIS WILL CAUSE TC 18P TO MOMENTARILY TRACK SOUTHWESTWARD INLAND TOWARDS DARWIN BEFORE RETURNING TO A WESTWARD TRAJECTORY BY TAU 48. TC NATHAN WILL MAKE LANDFALL SHORTLY AFTER TAU 12 AND WILL ERODE AS IT DRAGS OVER LAND BUT WILL EMERGE IN THE SOUTH INDIAN OCEAN AFTER TAU 48 AND SLOWLY RE-INTENSIFY. AVAILABLE MODEL GUIDANCE REMAINS IN GOOD AGREEMENT LENDING HIGH CONFIDENCE IN THE JTWC TRACK FORECAST. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 230600Z IS 18 FEET. NEXT WARNINGS AT 232100Z AND 240900Z.//