WTPS31 PGTW 171500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE WARNING// RMKS/ 1. TROPICAL CYCLONE 11P (WINSTON) WARNING NR 018 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 171200Z --- NEAR 17.5S 171.0W MOVEMENT PAST SIX HOURS - 090 DEGREES AT 02 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 015 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 010 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 100 NM NORTHEAST QUADRANT 120 NM SOUTHEAST QUADRANT 110 NM SOUTHWEST QUADRANT 120 NM NORTHWEST QUADRANT REPEAT POSIT: 17.5S 171.0W --- FORECASTS: 12 HRS, VALID AT: 180000Z --- 17.6S 170.8W MAX SUSTAINED WINDS - 095 KT, GUSTS 115 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 075 NM NORTHEAST QUADRANT 065 NM SOUTHEAST QUADRANT 065 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 155 NM NORTHEAST QUADRANT 120 NM SOUTHEAST QUADRANT 120 NM SOUTHWEST QUADRANT 175 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 260 DEG/ 02 KTS --- 24 HRS, VALID AT: 181200Z --- 17.7S 171.3W MAX SUSTAINED WINDS - 105 KT, GUSTS 130 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 045 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 075 NM NORTHEAST QUADRANT 075 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 140 NM NORTHEAST QUADRANT 125 NM SOUTHEAST QUADRANT 115 NM SOUTHWEST QUADRANT 140 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 265 DEG/ 07 KTS --- 36 HRS, VALID AT: 190000Z --- 17.8S 172.7W MAX SUSTAINED WINDS - 110 KT, GUSTS 135 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 045 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 070 NM NORTHEAST QUADRANT 075 NM SOUTHEAST QUADRANT 075 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 125 NM NORTHEAST QUADRANT 130 NM SOUTHEAST QUADRANT 120 NM SOUTHWEST QUADRANT 125 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 260 DEG/ 08 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 191200Z --- 18.1S 174.4W MAX SUSTAINED WINDS - 115 KT, GUSTS 140 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT 055 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 085 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 125 NM NORTHEAST QUADRANT 130 NM SOUTHEAST QUADRANT 125 NM SOUTHWEST QUADRANT 125 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 250 DEG/ 07 KTS --- 72 HRS, VALID AT: 201200Z --- 19.0S 177.1W MAX SUSTAINED WINDS - 110 KT, GUSTS 135 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 045 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 070 NM NORTHEAST QUADRANT 075 NM SOUTHEAST QUADRANT 075 NM SOUTHWEST QUADRANT 065 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 115 NM NORTHEAST QUADRANT 130 NM SOUTHEAST QUADRANT 125 NM SOUTHWEST QUADRANT 115 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 235 DEG/ 02 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 211200Z --- 19.5S 177.9W MAX SUSTAINED WINDS - 100 KT, GUSTS 125 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 120 HR POSIT: 115 DEG/ 04 KTS --- 120 HRS, VALID AT: 221200Z --- 20.1S 176.5W MAX SUSTAINED WINDS - 095 KT, GUSTS 115 KT WIND RADII VALID OVER OPEN WATER ONLY --- REMARKS: 171500Z POSITION NEAR 17.5S 171.0W. TROPICAL CYCLONE (TC) 11P (WINSTON), LOCATED APPROXIMATELY 115 NM NORTH-NORTHWEST OF NIUE, HAS TRACKED EASTWARD AT 02 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A BROAD AREA OF CENTRAL CONVECTION WITH VERY SHALLOW BANDING WRAPPING INTO THE CIRCULATION THAT HAS REMAINED MOSTLY UNCHANGED. THE OBSCURED LOW LEVEL CIRCULATION CENTER PROVIDES LOW CONFIDENCE IN THE CURRENT POSITION. THE INITIAL INTENSITY IS ASSESSED AT 90 KNOTS AND IS BASED ON DVORAK ESTIMATES FROM PGTW AND KNES REPORTING CURRENT INTENSITIES OF T5.0 (90 KNOTS). RECENT ANIMATED CIMSS MIMIC- TPW IMAGERY SHOWS A THIN BAND OF DRY AIR BEGINNING TO BE ENTRAINED INTO TC WINSTON, RESPONSIBLE FOR THE LACK OF INTENSIFICATION OBSERVED IN THE LAST SIX HOURS AND WILL HAMPER THE RATE OF INTENSIFICATION GOING FORWARD. HOWEVER, SEA SURFACE TEMPERATURES ARE HIGH (30 CELSIUS), AND FAVORABLE UPPER-LEVEL CONDITIONS WILL PERSIST THROUGHOUT THE FORECAST WITH LOW (10 TO 15 KNOTS) VERTICAL WIND SHEAR AND SUFFICIENT DIVERGENCE ALOFT. TC WINSTON IS FORECAST TO INTENSIFY TO 115 KNOTS BY TAU 48. TC WINSTON IS CURRENTLY ENTERING A WEAK STEERING ENVIRONMENT AND WILL REMAIN QUASI-STATIONARY FOR THE NEXT 24 HOURS BEFORE A RIDGE EXTENSION BUILDS SOUTH AND STEERS WINSTON ALONG A WESTWARD TRACK. BY TAU 72 A TROUGH TO THE WEST WILL WEAKEN THE WESTERN RIDGE AND ALLOW THE RIDGE POSITIONED TO THE NORTHEAST OF THE CYCLONE TO ASSUME STEERING, TURNING TC WINSTON TO THE SOUTHEAST. DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT ON THE GENERAL TRACK, BUT MODELS VARY GREATLY IN THE TIMING OF THE TURN, GIVING LOW CONFIDENCE TO THE FORECAST. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 171200Z IS 28 FEET. NEXT WARNINGS AT 172100Z, 180300Z, 180900Z AND 181500Z.//