WTXS31 PGTW 071500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 26S (SEROJA) WARNING NR 013// RMKS/ 1. TROPICAL CYCLONE 26S (SEROJA) 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: 071200Z --- NEAR 14.9S 115.9E MOVEMENT PAST SIX HOURS - 230 DEGREES AT 11 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 055 NM NORTHEAST QUADRANT 080 NM SOUTHEAST QUADRANT 075 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT REPEAT POSIT: 14.9S 115.9E --- FORECASTS: 12 HRS, VALID AT: 080000Z --- 16.0S 114.2E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT 080 NM SOUTHEAST QUADRANT 080 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 230 DEG/ 10 KTS --- 24 HRS, VALID AT: 081200Z --- 17.2S 112.6E MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT 080 NM SOUTHEAST QUADRANT 080 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 225 DEG/ 08 KTS --- 36 HRS, VALID AT: 090000Z --- 18.3S 111.4E MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 020 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT 100 NM SOUTHEAST QUADRANT 090 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 215 DEG/ 07 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 091200Z --- 19.5S 110.5E MAX SUSTAINED WINDS - 080 KT, GUSTS 100 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 020 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 010 NM SOUTHWEST QUADRANT 010 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 080 NM NORTHEAST QUADRANT 110 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 195 DEG/ 06 KTS --- 72 HRS, VALID AT: 101200Z --- 22.0S 109.9E MAX SUSTAINED WINDS - 110 KT, GUSTS 135 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 045 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 110 NM NORTHEAST QUADRANT 130 NM SOUTHEAST QUADRANT 130 NM SOUTHWEST QUADRANT 130 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 150 DEG/ 13 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 111200Z --- 26.4S 113.0E MAX SUSTAINED WINDS - 085 KT, GUSTS 105 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING EXTRATROPICAL RADIUS OF 064 KT WINDS - 010 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 000 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 120 NM NORTHEAST QUADRANT 140 NM SOUTHEAST QUADRANT 140 NM SOUTHWEST QUADRANT 140 NM NORTHWEST QUADRANT VECTOR TO 120 HR POSIT: 130 DEG/ 26 KTS --- 120 HRS, VALID AT: 121200Z --- 32.9S 122.6E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY EXTRATROPICAL RADIUS OF 034 KT WINDS - 130 NM NORTHEAST QUADRANT 150 NM SOUTHEAST QUADRANT 140 NM SOUTHWEST QUADRANT 150 NM NORTHWEST QUADRANT --- REMARKS: 071500Z POSITION NEAR 15.2S 115.5E. 07APR21. TROPICAL CYCLONE 26S (SEROJA), LOCATED APPROXIMATELY 456 NM NORTH-NORTHEAST OF LEARMONTH, AUSTRALIA, HAS TRACKED SOUTHWESTWARD AT 11 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS DISORGANIZED AND FRAGMENTED CONVECTION FLARING JUST WEST OF THE ASSESSED CORE OF TC 26S, INDICATIVE OF THE PERSISTENT EASTERLY VERTICAL WIND SHEAR (VWS). THE INITIAL POSITION IS ASSESSED WITH MODERATE CONFIDENCE BASED ON AN ANALYSIS OF THE LOW LEVEL SPIRAL BANDS EVIDENT ON THE EASTERN HALF OF THE LOW LEVEL CIRCULATION (LLC), SUPPORTED BY AN EXTRAPOLATION OF A WEAKLY DEFINED LLC IN A 070856Z SSMIS 91GHZ MICROWAVE IMAGE. THE INITIAL INTENSITY REMAINS SET AT 45 KNOTS WITH HIGH CONFIDENCE BASED ON MULTI-AGENCY DVORAK CURRENT INTENSITY ESTIMATES OF T3.0 (45 KTS) FROM BOTH PGTW AND APRF AND AN ADT ESTIMATE OF T3.1. WHILE STILL MARGINAL, ENVIRONMENTAL CONDITIONS HAVE IMPROVED SLIGHTLY, WITH CIMSS SHEAR ESTIMATES NOW BELOW 15 KNOTS AND WATER VAPOR IMAGERY STARTING SHOW SOME HINTS OF IMPROVED OUTFLOW ALOFT. TC 26S IS FORECAST TO CONTINUE TRACKING SOUTHWESTWARD ALONG THE NORTHWEST PERIPHERY OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) OVER WESTERN AUSTRALIA THROUGH TAU 48, ROUND THE RIDGE AXIS NEAR TAU 72 AND THEN ACCELERATE SOUTHEASTWARD THROUGH TAU 120 AHEAD OF AN APPROACHING MID- LATITUDE TROUGH. THE SYSTEM IS EXPECTED TO UNDERGO BINARY INTERACTION WITH TC 27S, BUT AS THE DOMINATE SYSTEM, THE INTERACTION IS NOT EXPECTED TO IMPACT THE OVERALL TRACK OF TC 26S, THOUGH SOME SLIGHT WESTWARD WOBBLE IS POSSIBLE BETWEEN TAU 24 AND 36. AS ENVIRONMENTAL SHEAR SLOWLY RELAXES, SLOW INTENSIFICATION IS FORECAST THROUGH 36. THE SYSTEM IS FORECAST TO RAPIDLY INTENSIFY FROM 60 KNOTS TO 110 KNOTS BETWEEN TAU 36 AND TAU 72 AS AN UPPER-LEVEL POINT SOURCE DEVELOPS ALOFT, VWS DROPS BELOW 10 KNOTS AND THE SYSTEM TAPS INTO A POLEWARD OUTFLOW CHANNEL. AFTER ROUNDING THE RIDGE AXIS, THE SYSTEM WILL RAPIDLY WEAKEN UNDER THE INFLUENCE OF CONVERGENT FLOW ALOFT, INCREASING SHEAR AND COOLER WATERS. AS THE SYSTEM MAKES LANDFALL SOUTH OF SHARK BAY AROUND TAU 96, IT WILL BEGIN EXTRA- TROPICAL TRANSITION (ETT), AND IS EXPECTED TO COMPLETE ETT BY TAU 120 BEFORE EMERGING INTO THE GREAT AUSTRALIAN BIGHT. DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU 48 WITH INCREASING ALONG AND CROSS-TRACK SPREAD THEREAFTER AS MODELS BEGIN TO DIFFER IN THE TIMING AND STRENGTH OF THE RECURVE. THE JTWC TRACK LIES ALONG THE WESTERN EDGE OF THE GUIDANCE ENVELOPE THROUGH THE DURATION OF THE FORECAST. OVERALL CONFIDENCE REMAINS MODERATE DUE TO THE UNCERTAIN EFFECTS OF THE BINARY INTERACTION WITH TC 27S. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 071200Z IS 20 FEET. NEXT WARNINGS AT 072100Z, 080300Z, 080900Z AND 081500Z. REFER TO TROPICAL CYCLONE 27S (TWENTYSEVEN) WARNINGS (WTXS32 PGTW) FOR SIX-HOURLY UPDATES.// NNNN