WTPS31 PGTW 170300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE WARNING// RMKS/ 1. TROPICAL CYCLONE 11P (WINSTON) 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: 170000Z --- NEAR 17.5S 171.8W MOVEMENT PAST SIX HOURS - 090 DEGREES AT 06 KTS POSITION ACCURATE TO WITHIN 040 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 171.8W --- FORECASTS: 12 HRS, VALID AT: 171200Z --- 17.5S 170.5W MAX SUSTAINED WINDS - 105 KT, GUSTS 130 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: 120 DEG/ 01 KTS --- 24 HRS, VALID AT: 180000Z --- 17.6S 170.3W MAX SUSTAINED WINDS - 120 KT, GUSTS 145 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: 240 DEG/ 01 KTS --- 36 HRS, VALID AT: 181200Z --- 17.7S 170.5W MAX SUSTAINED WINDS - 125 KT, GUSTS 150 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/ 05 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 190000Z --- 17.9S 171.6W MAX SUSTAINED WINDS - 120 KT, GUSTS 145 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 - 105 NM NORTHEAST QUADRANT 085 NM SOUTHEAST QUADRANT 125 NM SOUTHWEST QUADRANT 165 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 245 DEG/ 05 KTS --- 72 HRS, VALID AT: 200000Z --- 18.8S 173.7W 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 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: 200 DEG/ 02 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 210000Z --- 19.5S 174.0W MAX SUSTAINED WINDS - 100 KT, GUSTS 125 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 120 HR POSIT: 150 DEG/ 02 KTS --- 120 HRS, VALID AT: 220000Z --- 20.2S 173.6W MAX SUSTAINED WINDS - 095 KT, GUSTS 115 KT WIND RADII VALID OVER OPEN WATER ONLY --- REMARKS: 170300Z POSITION NEAR 17.5S 171.5W. TROPICAL CYCLONE 11P (WINSTON), LOCATED APPROXIMATELY 145 NM NORTHWEST OF NIUE, HAS TRACKED EASTWARD AT 06 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS DEEP CONVECTION CONTINUING TO IMPROVE WITH COLD CONVECTIVE TOPS WRAPPING INTO A VERY COMPACT EYE THAT HAS DEVELOPED OVER THE PAST TWO HOURS. A 162321Z GPM 91 GHZ MICROWAVE PASS INDICATES THAT DEEP CONVECTION COMPLETELY SURROUNDS A DISTINCT AND COMPACT MICROWAVE EYE FEATURE, LEADING TO HIGH CONFIDENCE IN THE INITIAL POSITION. THE INITIAL INTENSITY IS ASSESSED AT 90 KNOTS BASED ON DVORAK ESTIMATES OF T5.0 FROM ALL AGENCIES. ANALYSIS INDICATES THAT THE OVERALL ENVIRONMENT SURROUNDING TC WINSTON REMAINS FAVORABLE. VERTICAL WIND SHEAR (VWS) VALUES HAVE DECREASED OVER THE PAST SIX HOURS AND ARE NOW IN THE LOW RANGE (10 TO 15 KNOTS). SEA SURFACE TEMPERATURE REMAINS HIGH (30 CELSIUS) AND THERE ARE INDICATIONS OF THE DEVELOPMENT OF AN EQUATORWARD OUTFLOW CHANNEL IN ADDITION TO THE ESTABLISHED EASTWARD CHANNEL. THE PRIMARY STEERING MECHANISM REMAINS THE DEEP-LAYER NEAR- EQUATORIAL RIDGE TO THE NORTH, WHICH WILL CONTINUE TO STEER TC WINSTON ON ITS CURRENT EASTWARD TRACK FOR THE NEXT 12 HOURS, ALBEIT AT A MUCH SLOWER PACE, TC WINSTON HAVING ALREADY SLOWED SIGNIFICANTLY SINCE THE PREVIOUS WARNING. AS A RIDGE BUILDS TO THE SOUTH OF THE TC, A DEEP-LAYER SUBTROPICAL RIDGE (STR) WILL SIMULTANEOUSLY BUILD IN FROM THE EAST, CAUSING TC WINSTON TO BECOME QUASI-STATIONARY BY TAU 24. AFTER TAU 36, UNDER THE COMBINED INFLUENCE OF THE TWO AFOREMENTIONED RIDGES, TC WINSTON WILL TRANSLATE TO A WEST-SOUTHWESTWARD TRACK AND ACCELERATE THROUGH TAU 72. THROUGH THE REMAINING PORTION OF THE FORECAST PERIOD, TC WINSTON WILL TRANSITION TO A MORE SOUTHWARD TRACK TOWARDS A WEAKNESS IN THE STR AHEAD OF AN ADVANCING MID-LATITUDE TROUGH. ENVIRONMENTAL CONDITIONS ARE FAVORABLE FOR A PERIOD OF RAPID INTENSIFICATION OVER THE NEXT 24 HOURS, PEAK INTENSITY REACHING 125 KNOTS BY TAU 36. THEREAFTER THE SYNOPTIC ENVIRONMENT REMAINS SUPPORTIVE OF MAINTAINING TC WINSTON AS AN INTENSE SYSTEM THROUGH THE END OF THE FORECAST PERIOD. DYNAMIC MODEL GUIDANCE HAS COME INTO BETTER AGREEMENT BUT STILL DEPICTS MODERATE UNCERTAINTY AFTER TAU 48. DUE TO THIS UNCERTAINTY, THERE IS LOW CONFIDENCE TO THE JTWC FORECAST TRACK. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 170000Z IS 32 FEET. NEXT WARNINGS AT 170900Z, 171500Z, 172100Z AND 180300Z.//