WTPS31 PGTW 162100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE WARNING// RMKS/ 1. TROPICAL CYCLONE 11P (WINSTON) WARNING NR 015 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 161800Z --- NEAR 17.5S 172.4W MOVEMENT PAST SIX HOURS - 070 DEGREES AT 12 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 075 KT, GUSTS 090 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 172.4W --- FORECASTS: 12 HRS, VALID AT: 170600Z --- 17.2S 171.2W MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 020 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 150 NM NORTHEAST QUADRANT 150 NM SOUTHEAST QUADRANT 115 NM SOUTHWEST QUADRANT 115 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 075 DEG/ 04 KTS --- 24 HRS, VALID AT: 171800Z --- 17.0S 170.4W MAX SUSTAINED WINDS - 095 KT, GUSTS 115 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 020 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 045 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 150 NM NORTHEAST QUADRANT 150 NM SOUTHEAST QUADRANT 105 NM SOUTHWEST QUADRANT 105 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 090 DEG/ 02 KTS --- 36 HRS, VALID AT: 180600Z --- 17.0S 170.0W MAX SUSTAINED WINDS - 100 KT, GUSTS 125 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 020 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 145 NM NORTHEAST QUADRANT 145 NM SOUTHEAST QUADRANT 115 NM SOUTHWEST QUADRANT 115 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 240 DEG/ 01 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 181800Z --- 17.1S 170.2W MAX SUSTAINED WINDS - 110 KT, GUSTS 135 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 020 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 155 NM NORTHEAST QUADRANT 155 NM SOUTHEAST QUADRANT 125 NM SOUTHWEST QUADRANT 125 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 250 DEG/ 07 KTS --- 72 HRS, VALID AT: 191800Z --- 18.0S 173.1W MAX SUSTAINED WINDS - 110 KT, GUSTS 135 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 035 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 055 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 110 NM NORTHEAST QUADRANT 125 NM SOUTHEAST QUADRANT 145 NM SOUTHWEST QUADRANT 130 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 235 DEG/ 04 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 201800Z --- 18.8S 174.4W MAX SUSTAINED WINDS - 100 KT, GUSTS 125 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 120 HR POSIT: 185 DEG/ 03 KTS --- 120 HRS, VALID AT: 211800Z --- 20.1S 174.5W MAX SUSTAINED WINDS - 095 KT, GUSTS 115 KT WIND RADII VALID OVER OPEN WATER ONLY --- REMARKS: 162100Z POSITION NEAR 17.4S 172.1W. TROPICAL CYCLONE 11P (WINSTON), LOCATED APPROXIMATELY 216 NM SOUTH-SOUTHWEST OF PAGO PAGO, HAS TRACKED EAST-NORTHEASTWARD AT 12 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS DEEP CONVECTION IMPROVING SINCE THE PREVIOUS WARNING, WITH OVERSHOOTING COLD CONVECTIVE TOPS WRAPPING INTO A CENTRAL DENSE OVERCAST. A 161812Z SSMIS 91 GHZ MICROWAVE IMAGE DEPICTS CENTRAL CONVECTION COMPLETELY SURROUNDING A WELL- DEFINED MICROWAVE EYE FEATURE, GIVING HIGH CONFIDENCE IN THE INITIAL POSITION. THE INITIAL INTENSITY IS ASSESSED AT 75 KNOTS BASED ON DVORAK ESTIMATES FROM PGTW REPORTING T4.5. ENVIRONMENTAL ANALYSIS INDICATES THAT TC WINSTON IS CURRENTLY TRACKING IN AN AREA THAT IS ADVANTAGEOUS FOR FURTHER INTENSIFICATION WITH FAVORABLE SEA SURFACE TEMPERATURES (30 CELSIUS), LOW TO MODERATE (15 TO 20 KNOTS) VERTICAL WIND SHEAR AND A STRONG POLEWARD OUTFLOW CHANNEL. THE PRIMARY STEERING MECHANISM IS A DEEP-LAYER NEAR-EQUATORIAL RIDGE TO THE NORTH, WHICH WILL CONTINUE TO STEER TC WINSTON ON ITS CURRENT EAST- NORTHEASTWARD TRACK THROUGH TAU 24. BETWEEN TAUS 24 AND 48, AS THE WESTERN RIDGE BUILDS TO THE SOUTH OF THE TC, A DEEP-LAYER SUBTROPICAL RIDGE (STR) WILL BUILD IN TO THE EAST, CAUSING TC WINSTON TO RAPIDLY SLOW ITS FORWARD MOVEMENT, ULTIMATELY BECOMING QUASI-STATIONARY BY TAU 48. AFTER TAU 48, UNDER THE COMBINED INFLUENCE OF THE TWO AFOREMENTIONED RIDGES, TC WINSTON WILL TRANSLATE TO A WEST-SOUTHWESTWARD TRACK THROUGH TAU 96. AFTERWARDS, THE TRACK WILL BECOME MORE SOUTHWARD, TRACKING TOWARDS A WEAKNESS IN THE STR AHEAD OF AN ADVANCING MID-LATITUDE TROUGH. ENVIRONMENTAL CONDITIONS WILL REMAIN FAVORABLE FOR INTENSIFICATION, AND TC WINSTON IS EXPECTED TO REACH 110 KNOTS BY TAU 48. DUE TO THE UNCERTAINTY IN THE OVERALL SYNOPTIC ENVIRONMENT, DYNAMIC MODEL GUIDANCE IS IN DISAGREEMENT BEYOND TAU 24, AS THE CYCLONE BECOMES QUASI-STATIONARY, BUT HAS COME INTO BETTER AGREEMENT OVER THE PAST 12 HOURS IN FORECASTING THE TURN TO THE WEST. DUE TO THIS UNCERTAINTY, THERE IS LOW CONFIDENCE TO THE JTWC FORECAST TRACK BEYOND TAU 24. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 161800Z IS 28 FEET. NEXT WARNINGS AT 170900Z AND 172100Z.//