WTXS31 PGTW 150900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 01S (ONE) WARNING NR 002// RMKS/ 1. TROPICAL CYCLONE 01S (ONE) WARNING NR 002 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 150600Z --- NEAR 10.4S 71.0E MOVEMENT PAST SIX HOURS - 255 DEGREES AT 08 KTS POSITION ACCURATE TO WITHIN 030 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 045 NM NORTHEAST QUADRANT 075 NM SOUTHEAST QUADRANT 065 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT REPEAT POSIT: 10.4S 71.0E --- FORECASTS: 12 HRS, VALID AT: 151800Z --- 10.9S 69.1E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 045 NM NORTHEAST QUADRANT 075 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 255 DEG/ 12 KTS --- 24 HRS, VALID AT: 160600Z --- 11.5S 66.8E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 045 NM NORTHEAST QUADRANT 075 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 255 DEG/ 12 KTS --- 36 HRS, VALID AT: 161800Z --- 12.1S 64.5E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 035 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 265 DEG/ 10 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 170600Z --- 12.2S 62.4E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 035 NM NORTHEAST QUADRANT 065 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 285 DEG/ 13 KTS --- 72 HRS, VALID AT: 180600Z --- 10.9S 57.3E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER RADIUS OF 034 KT WINDS - 020 NM NORTHEAST QUADRANT 065 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 295 DEG/ 18 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 190600Z --- 7.6S 50.8E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER --- REMARKS: 150900Z POSITION NEAR 10.5S 70.5E. TROPICAL CYCLONE 01S (ONE), LOCATED APPROXIMATELY 217 NM SOUTH- SOUTHWEST OF DIEGO GARCIA, HAS TRACKED WEST-SOUTHWESTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. THE CURRENT POSITION AND INTENSITY ARE BASED ON A 150453Z ASCAT PASS. TC 01S IS TRACKING WEST-SOUTHWESTWARD ALONG THE PERIPHERY OF A DEEP-LAYERED SUBTROPICAL STEERING RIDGE SITUATED TO THE SOUTH AND EAST. THE COMPACT SYSTEM HAS CONTINUED TO CONSOLIDATE OVER THE PAST SIX HOURS UNDER THE INFLUENCE OF LOW VERTICAL WIND SHEAR AND FAVORABLE UPPER LEVEL OUTFLOW. THESE ENVIRONMENTAL CONDITIONS ARE EXPECTED TO REMAIN FAVORABLE FOR THE NEXT 36 TO 48 HOURS. HOWEVER, ALONG TRACK SEA SURFACE TEMPERATURES ARE ONLY 25 TO 26 DEGREES CELSIUS. THE COMBINED INFLUENCES OF FAVORABLE ATMOSPHERIC CONDITIONS AND MARGINAL SEA SURFACE TEMPERATURES SHOULD RESULT IN A SLOW WEAKENING TREND DURING THE INITIAL PORTION OF THE FORECAST PERIOD. AFTER TAU 48, VERTICAL WIND SHEAR IS EXPECTED TO INCREASE, DISSIPATING THE SYSTEM BY TAU 96. TC 01S WILL TRACK WEST-SOUTHWESTWARD UNDER THE CONTINUED STEERING INFLUENCE OF THE SUBTROPICAL RIDGE TO THE SOUTHEAST THROUGH TAU 36. AROUND TAU 48, A SECOND SUBTROPICAL RIDGE BUILDING TO THE SOUTHWEST IS EXPECTED TO BECOME THE PRIMARY STEERING INFLUENCE AND TURN TC 01S TOWARD A WEST-NORTHWESTWARD TRACK. NUMERICAL MODELS ARE IN GOOD OVERALL AGREEMENT, ALTHOUGH THE ECMWF DETERMINISTIC MODEL PREDICTS A TRACK TO THE SOUTH OF THE PRIMARY MODEL GROUPING. THE COMPACT CIRCULATION IS VULNERABLE TO ANY CHANGE IN ANTICIPATED ENVIRONMENTAL CONDITIONS, WHICH COULD RESULT IN STRUCTURAL CHANGES THAT EFFECT THE STEERING LEVEL. THUS, THE OUTLIER ECMWF MODEL SOLUTION IS NOT CONSIDERED IMPLAUSIBLE IN THIS CASE. OVERALL, THERE IS FAIR CONFIDENCE IN THE CURRENT TRACK FORECAST. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 150600Z IS 12 FEET. NEXT WARNINGS AT 151500Z, 152100Z, 160300Z AND 160900Z.// NNNN