WTPS31 PGTW 061500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 18P (ZENA) WARNING NR 005// RMKS/ 1. TROPICAL CYCLONE 18P (ZENA) WARNING NR 005 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 061200Z --- NEAR 19.4S 177.4E MOVEMENT PAST SIX HOURS - 115 DEGREES AT 24 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY SATELLITE 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 - 050 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT REPEAT POSIT: 19.4S 177.4E --- FORECASTS: 12 HRS, VALID AT: 070000Z --- 20.5S 177.7W MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING SUBTROPICAL RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 105 DEG/ 24 KTS --- 24 HRS, VALID AT: 071200Z --- 21.5S 172.6W MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING SUBTROPICAL VECTOR TO 36 HR POSIT: 105 DEG/ 25 KTS --- 36 HRS, VALID AT: 080000Z --- 22.6S 167.4W MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY SUBTROPICAL --- REMARKS: 061500Z POSITION NEAR 19.7S 178.6E. TROPICAL CYCLONE (TC) 18P (ZENA), LOCATED APPROXIMATELY 96 NM SOUTHWEST OF SUVA, FIJI, HAS TRACKED EAST-SOUTHEASTWARD AT 24 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY INDICATES A RAPIDLY WEAKENING SYSTEM WITH DECAYING DEEP CONVECTION SHEARED EAST OF THE CENTER. DVORAK INTENSITY ESTIMATES HAVE DECREASED TO 4.0 (65 KNOTS) AND THE INITIAL INTENSITY IS NOW ASSESSED AT 65 KNOTS. UPPER-LEVEL ANALYSIS INDICATES INCREASING WESTERLY VERTICAL WIND SHEAR (VWS) AT STRONG LEVELS (30 TO 40 KNOTS) PARTIALLY OFFSET BY ROBUST POLEWARD OUTFLOW. TC 18P IS TRACKING QUICKLY EAST-SOUTHEASTWARD UNDER ENHANCED FLOW BETWEEN THE SUBTROPICAL RIDGE AND A BROAD TROUGH, AND IS FORECAST TO CONTINUE TRACKING EAST-SOUTHEASTWARD THROUGH THE FORECAST PERIOD. TC 18P IS FORECAST TO WEAKEN THROUGH THE FORECAST PERIOD AS IT ENCOUNTERS INCREASING VWS ASSOCIATED WITH SUBTROPICAL WESTERLY FLOW. THE SYSTEM IS FORECAST TO TRANSITION TO A SUBTROPICAL LOW BY TAU 36, HOWEVER, TC 18P MAY WEAKEN BELOW 35 KNOTS AFTER TAU 24. DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT OVERALL, THEREFORE THERE IS HIGH CONFIDENCE IN THE OFFICIAL FORECAST. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 061200Z IS 20 FEET. NEXT WARNINGS AT 062100Z, 070300Z, 070900Z AND 071500Z.//