WTXS32 PGTW 080300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 27S (TWENTYSEVEN) WARNING NR 013// RMKS/ 1. TROPICAL CYCLONE 27S (TWENTYSEVEN) WARNING NR 013 02 ACTIVE TROPICAL CYCLONES IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 080000Z --- NEAR 16.0S 106.2E MOVEMENT PAST SIX HOURS - 045 DEGREES AT 03 KTS POSITION ACCURATE TO WITHIN 025 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 - 065 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 075 NM SOUTHWEST QUADRANT 065 NM NORTHWEST QUADRANT REPEAT POSIT: 16.0S 106.2E --- FORECASTS: 12 HRS, VALID AT: 081200Z --- 15.4S 106.8E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT 000 NM SOUTHEAST QUADRANT 080 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 075 DEG/ 08 KTS --- 24 HRS, VALID AT: 090000Z --- 15.0S 108.4E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 090 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 110 DEG/ 13 KTS --- 36 HRS, VALID AT: 091200Z --- 15.9S 110.9E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 080 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 155 DEG/ 14 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 100000Z --- 18.5S 112.2E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER --- REMARKS: 080300Z POSITION NEAR 15.8S 106.4E. 08APR21. TROPICAL CYCLONE (TC) 27S (TWENTYSEVEN), LOCATED APPROXIMATELY 586 NM NORTHWEST OF LEARMONTH, AUSTRALIA, HAS TRACKED NORTHEASTWARD AT 03 KNOTS OVER THE PAST SIX HOURS. ANIMATED 6-HR MULTISPECTRAL SATELLITE IMAGERY SHOWS THE SYSTEM HAS MOSTLY MAINTAINED CONVECTIVE SIGNATURE AS IT STAYED QUASI-STATIONARY (QS)IN A WEAK STEERING ENVIRONMENT EVEN AS THE MAIN CONVECTION REMAINS SHEARED WESTWARD OF A PARTLY-EXPOSED LOW LEVEL CIRCULATION. THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE BASED ON A NOTCH FEATURE IN THE 072253Z SSMIS 37GHZ MICROWAVE IMAGE. THE INITIAL INTENSITY OF 40KTS IS BASED ON THE ADT ESTIMATE OF T2.7/39KTS AND HEDGED HIGHER THAN THE DVORAK ESTIMATES OF T2.5/35KTS FROM PGTW AND KNES TO REFLECT THE SUSTAINED CONVECTIVE SIGNATURE. ANALYSIS INDICATES THE CYCLONE IS IN A MARGINAL ENVIRONMENT WITH STRONG SUBSIDENCE ALOFT ALONG THE EASTERN HALF DUE TO THE OUTFLOW FROM TC 26S AND MODERATE TO STRONG (20-25KT) EASTERLY VERTICAL WIND SHEAR THAT ARE PARTLY OFFSET BY WARM (29C) SEA SURFACE TEMPERATURE. THE SYSTEM IS IN A NEUTRAL AREA BETWEEN A LOW REFLECTION OF THE SUBTROPICAL RIDGE TO THE SOUTHWEST, WEAK NEAR EQUATORIAL RIDGING TO THE NORTHWEST, AND OUTFLOW PRESSURE FROM AN APPROACHING TC 26S, CURRENTLY 420NM TO THE EAST. AS TC 26S GETS CLOSER, A BINARY INTERACTION WILL COMMENCE DUE TO FUJIWARA EFFECT RESULTING IN TC 26S TRACKING CYCLONICALLY INTO AN ARC NORTHEASTWARD. THE WARM WATER AND INCREASED OUTFLOW WILL MARGINALLY OFFSET THE VWS AND PROMOTE A MODEST INTENSIFICATION TO A PEAK OF 50KTS AS IT CRESTS THE ARC. AFTERWARD, IT WILL RAPIDLY DECAY AS IT GETS RAPIDLY ABSORBED INTO THE LARGER AND MUCH MORE DOMINANT TC 26S LEADING TO DISSIPATION BY TAU 48, POSSIBLY SOONER. THE NUMERICAL MODELS ARE IN FAIRLY GOOD AGREEMENT WITH GRADUAL SPREADING; HOWEVER, GIVEN THE UNCERTAINTIES IN THE INITIAL STORM MOTION AND THE COMPLEX DYNAMICS OF THE BINARY INTERACTION, THERE IS LOW CONFIDENCE IN THE JTWC TRACK FORECAST. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 080000Z IS 15 FEET. NEXT WARNINGS AT 080900Z, 081500Z, 082100Z AND 090300Z. REFER TO TROPICAL CYCLONE 26S (SEROJA) WARNINGS (WTXS31 PGTW) FOR SIX-HOURLY UPDATES.// NNNN