WTXS32 PGTW 060900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 27S (TWENTYSEVEN) WARNING NR 006// RMKS/ 1. TROPICAL CYCLONE 27S (TWENTYSEVEN) WARNING NR 006 02 ACTIVE TROPICAL CYCLONES IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 060600Z --- NEAR 16.2S 105.8E MOVEMENT PAST SIX HOURS - 065 DEGREES AT 02 KTS POSITION ACCURATE TO WITHIN 040 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 - 085 NM NORTHEAST QUADRANT 105 NM SOUTHEAST QUADRANT 095 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT REPEAT POSIT: 16.2S 105.8E --- FORECASTS: 12 HRS, VALID AT: 061800Z --- 16.2S 105.9E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 010 NM NORTHEAST QUADRANT 090 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 045 DEG/ 01 KTS --- 24 HRS, VALID AT: 070600Z --- 16.1S 106.0E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 000 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 340 DEG/ 02 KTS --- 36 HRS, VALID AT: 071800Z --- 15.8S 105.9E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 020 NM NORTHEAST QUADRANT 090 NM SOUTHEAST QUADRANT 090 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 020 DEG/ 03 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 080600Z --- 15.2S 106.1E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 030 NM NORTHEAST QUADRANT 080 NM SOUTHEAST QUADRANT 090 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 085 DEG/ 05 KTS --- 72 HRS, VALID AT: 090600Z --- 15.0S 108.1E 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 - 050 NM NORTHEAST QUADRANT 130 NM SOUTHEAST QUADRANT 080 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 125 DEG/ 11 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 100600Z --- 17.5S 111.7E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER --- REMARKS: 060900Z POSITION NEAR 16.2S 105.8E. 06APR21. TROPICAL CYCLONE 27S (TWENTYSEVEN), LOCATED APPROXIMATELY 596 NM NORTHWEST OF LEARMONTH, AUSTRALIA, HAS TRACKED EAST-NORTHEASTWARD AT 02 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL IMAGERY SHOWS THAT THE LOW LEVEL CIRCULATION CENTER (LLCC) HAS BECOME PARTIALLY EXPOSED OVER THE PREVIOUS FEW HOURS, WITH MODERATE LOW LEVEL BANDING FEATURES PARTICULARLY EVIDENT ON THE NORTHERN SIDE OF THE LLCC. DUE TO A LACK OF RECENT MICROWAVE IMAGERY, THE INITIAL POSITION IS ASSESSED WITH ONLY MODERATE CONFIDENCE BASED ON THE PARTIALLY EXPOSED LLCC, THE EXACT CENTER OF WHICH IS STILL COVERED BY FLARING CONVECTION AND CONVECTIVE BLOWOFF. THE INITIAL INTENSITY IS ASSESSED AT 40 KNOTS WITH MODERATE CONFIDENCE, BASED ON MULTI-AGENCY DVORAK CURRENT INTENSITY ESTIMATES OF T2.5 (35 KTS) FROM PGTW AND APRFS, HEDGED SLIGHTLY HIGHER BASED ON AN EARLIER 060205Z ASCAT PASS WHICH INDICATED A SWATH OF 40 KNOT WINDS IN THE SOUTHWESTERN QUADRANT OF THE CIRCULATION. ENVIRONMENTAL ANALYSIS REVEALS MARGINAL CONDITIONS CHARACTERIZED BY LOW TO MODERATE (15-20 KTS) NORTHEASTERLY VWS AND WARM (29C) SSTS, BEING OFFSET SOMEWHAT BY ROBUST POLEWARD OUTFLOW. EFFECTIVE SHEAR IS LIKELY HIGHER, WITH WATER VAPOR IMAGERY AND HWRF UPPER-LEVEL FLOW ANALYSIS INDICATING THAT THE OUTFLOW FROM TC 26S IS IMPINGING ON THE NORTHEAST SIDE OF TC 27S, WHICH IS ALSO SUPPORTED BY THE OVERALL PRESENTATION IN THE VISIBLE LOOP. THE OVERALL FORECAST PHILOSOPHY HAS NOT CHANGED, HOWEVER THERE REMAINS VERY HIGH UNCERTAINTY IN THE STRENGTH AND TIMING OF THE EXPECTED BINARY INTERACTION WITH TC 26S, LEADING TO FAIRLY LARGE CHANGES IN THE OVERALL TRACK WITH THIS FORECAST. TC 27S IS FORECAST TO DRIFT SLOWLY NORTH-NORTHEASTWARD, OR POSSIBLY PERFORM A CLOCKWISE LOOP, OVER THE NEXT 24-36 HOURS, AS IT REMAINS IN A WEAK STEERING ENVIRONMENT AND BLOCKED FROM ANY SIGNIFICANT EASTWARD MOVEMENT DUE TO THE PRESENCE OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) ENTRENCHED OVER WESTERN AUSTRALIA. NEAR TAU 48, AS TC 26S APPROACHES FROM THE NORTHEAST, THE SYSTEM WILL BEGIN TO MOVE MORE NORTHEASTWARD ALONG THE WESTERN SIDE OF THE PRESSURE GRADIENT BETWEEN IT AND TC 26S. AT THIS POINT, THE TWO SYSTEMS WILL BE APPROXIMATELY 400NM APART, AND TC 27S WILL BEGIN TO BECOME CAPTURED BY TC 26S AND BEGIN TO ACCELERATE EAST, THEN SOUTHEAST AROUND THE NORTHERN PERIPHERY OF TC 26S. LITTLE TO NO INTENSIFICATION IS EXPECTED THROUGH TAU 36, AS THE OVERALL ENVIRONMENT SHOWS LITTLE SIGN OF CHANGE. BY TAU 36, SOME MODELS ARE SUGGESTING THE DEVELOPMENT OF A POINT SOURCE ALOFT OVER THE SYSTEM, WHICH SHOULD ALLOW FOR A BRIEF PERIOD OF INTENSIFICATION, PEAKING AT 50 KNOTS BY TAU 72, AS IT MOVED OUT FROM UNDER THE OUTFLOW FROM TC 26S, BUT WILL RAPIDLY DISSIPATE BY TAU 96 AS IT ONCE AGAIN COMES UNDER INCREASING VWS AND MERGES WITH TC 26S. NUMERICAL MODEL GUIDANCE IS IN VERY POOR AGREEMENT. WHILE THE BULK OF THE GUIDANCE AGREES ON THE OVERALL SCENARIO THERE ARE LARGE DISPARITIES IN THE TIMING OVER THE TURN TO THE EAST AND THE AMOUNT OF INTERACTION WITH TC 26S, WITH SOME MODELS SUGGESTING TC 27S WILL NOT BE CAPTURED BY TC 26S AND INSTEAD WILL BE EJECTED TO THE NORTHWEST. DUE TO THE VERY ERRATIC MOTION EXPECTED IN THE EARLY PORTION OF THE FORECAST AND THE COMPLEX NATURE OF THE BINARY INTERACTION, THERE IS VERY LOW CONDFIDENCE IN THE JTWC FORECAST TRACK. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 060600Z IS 16 FEET. NEXT WARNINGS AT 061500Z, 062100Z, 070300Z AND 070900Z. REFER TO TROPICAL CYCLONE 26S (SEROJA) WARNINGS (WTXS31 PGTW) FOR SIX-HOURLY UPDATES.// NNNN