WTXS51 PGTW 070900 WARNING ATCG MIL 26S SIO 210407081833 2021040706 26S SEROJA 012 02 230 15 SATL 060 T000 142S 1168E 045 R034 060 NE QD 060 SE QD 075 SW QD 070 NW QD T012 153S 1150E 050 R034 060 NE QD 060 SE QD 070 SW QD 070 NW QD T024 166S 1132E 055 R050 040 NE QD 030 SE QD 030 SW QD 040 NW QD R034 060 NE QD 060 SE QD 070 SW QD 070 NW QD T036 177S 1119E 060 R050 040 NE QD 030 SE QD 030 SW QD 040 NW QD R034 070 NE QD 070 SE QD 080 SW QD 070 NW QD T048 190S 1108E 080 R064 020 NE QD 020 SE QD 010 SW QD 010 NW QD R050 000 NE QD 020 SE QD 000 SW QD 000 NW QD R034 070 NE QD 080 SE QD 090 SW QD 070 NW QD T072 208S 1095E 110 R064 045 NE QD 045 SE QD 040 SW QD 035 NW QD R050 030 NE QD 030 SE QD 030 SW QD 040 NW QD R034 090 NE QD 090 SE QD 100 SW QD 090 NW QD T096 246S 1108E 090 R064 010 NE QD 020 SE QD 020 SW QD 000 NW QD R050 040 NE QD 040 SE QD 050 SW QD 040 NW QD R034 110 NE QD 110 SE QD 120 SW QD 100 NW QD T120 315S 1193E 045 AMP 120HR BECOMING EXTRATROPICAL SUBJ: TROPICAL CYCLONE 26S (SEROJA) WARNING NR 012 1. TROPICAL CYCLONE 26S (SEROJA) WARNING NR 012 02 ACTIVE TROPICAL CYCLONES IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 070600Z --- NEAR 14.2S 116.8E MOVEMENT PAST SIX HOURS - 230 DEGREES AT 15 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 - 060 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 075 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT REPEAT POSIT: 14.2S 116.8E --- FORECASTS: 12 HRS, VALID AT: 071800Z --- 15.3S 115.0E 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 070 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 235 DEG/ 11 KTS --- 24 HRS, VALID AT: 080600Z --- 16.6S 113.2E 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 060 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 230 DEG/ 08 KTS --- 36 HRS, VALID AT: 081800Z --- 17.7S 111.9E MAX SUSTAINED WINDS - 060 KT, GUSTS 075 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 - 070 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 080 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 220 DEG/ 08 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 090600Z --- 19.0S 110.8E 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 - 000 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 000 NM SOUTHWEST QUADRANT 000 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT 080 NM SOUTHEAST QUADRANT 090 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 215 DEG/ 05 KTS --- 72 HRS, VALID AT: 100600Z --- 20.8S 109.5E 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 - 030 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 090 NM NORTHEAST QUADRANT 090 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 165 DEG/ 10 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 110600Z --- 24.6S 110.8E MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT WIND RADII VALID OVER OPEN WATER ONLY 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 - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 110 NM NORTHEAST QUADRANT 110 NM SOUTHEAST QUADRANT 120 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT VECTOR TO 120 HR POSIT: 135 DEG/ 25 KTS --- 120 HRS, VALID AT: 120600Z --- 31.5S 119.3E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING EXTRATROPICAL --- REMARKS: 070900Z POSITION NEAR 14.5S 116.3E. 07APR21. TROPICAL CYCLONE 26S (SEROJA), LOCATED APPROXIMATELY 510 NM NORTH-NORTHEAST OF LEARMONTH, AUSTRALIA, HAS TRACKED SOUTHWESTWARD AT 15 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS WELL-DEFINED LOW LEVEL CLOUD BANDS WRAPPING INTO A PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) POSITIONED ON THE EASTERN EDGE OF FLARING, SHEARED CONVECTION. A 070525Z AMSR2 89GHZ COLOR COMPOSITE AND A 070645Z GMI 37GHZ MICROWAVE IMAGE SHOWED THE LOWER LEVEL CLOUD BANDS WRAPPING INTO A WELL DEFINED LLCC TO GOOD EFFECT AND LENT HIGH CONFIDENCE TO THE INITIAL POSITION. THE INITIAL INTENSITY IS ASSESSED AT 45 KNOTS WITH MODERATE CONFIDENCE BASED ON A BLEND OF MULTI-AGENCY DVORAK INTENSITY ESTIMATES BETWEEN T2.5-T3.0 (35 TO 45 KTS), AND AN ADT ESTIMATE OF T3.0. THE SYSTEM REMAINS COCOONED IN A MARGINALLY SUPPORTIVE ENVIRONMENT CHARACTERIZED BY MODERATE (15-20 KTS) EASTERLY VWS OFFSET BY DIFFLUENT FLOW ALOFT, THOUGH THERE IS NO DISTINCT OUTFLOW CHANNEL AT PRESENT. TC 26S IS FORECAST TO CONTINUE TRACKING SOUTHWESTWARD ALONG THE NORTHWEST PERIPHERY OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTERED OVER WESTERN AUSTRALIA THROUGH 72, BEFORE ROUNDING THE RIDGE AXIS NEAR TAU 72, AND THEN ACCELERATING SOUTHEASTWARD THROUGH TAU 120. THE SYSTEM IS EXPECTED TO MAKE LANDFALL SOUTH OF SHARK BAY NEAR TAU 108. SLOW INTENSIFICATION IS FORECAST OVER THE NEXT 36 HOURS AS THE SYSTEM MOVES SLOWLY INTO A GENERALLY MORE FAVORABLE ENVIRONMENT WITH INCREASED MOISTURE AND DECREASED VWS. TC 26S IS FORECAST TO RAPIDLY INTENSIFY, FROM 60 KNOTS TO 110 KNOTS BETWEEN TAU 48 AND 72, AS IT APPROACHES THE RIDGE AXIS, VWS DROPS TO THE 5-10 KNOT RANGE AND A COMPACT POINT SOURCE DEVELOPS ALOFT OVER TOP OF THE SYSTEM. AFTER ROUNDING THE RIDGE AND ACCELERATING SOUTHEASTWARD, INCREASING SHEAR, COOLER WATERS AND ULTIMATELY LAND INTERACTION WILL LEAD TO RAPID WEAKENING THROUGH THE REMAINDER OF THE FORECAST. THE SYSTEM IS EXPECTED TO BEGIN EXTRA-TROPICAL TRANSITION AFTER LANDFALL AS IT MOVES EAST OF PERTH. AT THIS POINT, THE BINARY INTERACTION WITH TC 27S IS NOT EXPECTED TO IMPACT THE TRACK FORECAST, BUT THERE REMAINS A LOW PROBABILITY OF A SLIGHT WOBBLE FURTHER WEST IN THE MID-RANGE PORTION OF THE FORECAST AS THE TWO SYSTEMS BEGIN TO INTERACT WITH ONE ANOTHER. DYNAMIC MODEL GUIDANCE IS IN OVERALL GOOD AGREEMENT ON THE OVERALL SCENARIO, WITH SOME DIFFERENCES IN THE TIMING AND SHARPNESS OF THE RECURVE STARTING TO EMERGE. IN PARTICULAR, THE ECMWF HAS SHIFTED MUCH FURTHER TO THE WEST IN THE LATEST RUN AND IS NO THE WESTERN-MOST OUTLIER AMONGST THE CONSENSUS MEMBERS. THE JTWC FORECAST LIES ALONG THE WESTERN EDGE OF THE GUIDANCE ENVELOPE AS A NOD TOWARDS THE ECMWF, BUT REMAINS CONSISTENT WITH THE PREVIOUS FORECAST TRACK. OVERALL CONFIDENCE REMAINS MODERATE IN LIGHT OF THE UNCERTAINTY ASSOCIATED WITH THE BINARY INTERACTION WITH TC 27S. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 070600Z IS 20 FEET. NEXT WARNINGS AT 071500Z, 072100Z, 080300Z AND 080900Z. FOR SIX-HOURLY UPDATES.// 2621040112 93S1219E 25 2621040118 96S1218E 25 2621040200 100S1219E 20 2621040206 104S1222E 20 2621040212 110S1223E 25 2621040218 113S1227E 25 2621040300 113S1230E 25 2621040306 111S1232E 25 2621040312 107S1238E 30 2621040318 107S1240E 30 2621040400 105S1241E 30 2621040406 101S1239E 30 2621040412 104S1232E 35 2621040418 105S1229E 45 2621040500 108S1224E 45 2621040506 110S1219E 50 2621040506 110S1219E 50 2621040512 111S1214E 50 2621040512 111S1214E 50 2621040518 113S1206E 50 2621040518 113S1206E 50 2621040600 114S1200E 55 2621040600 114S1200E 55 2621040606 116S1197E 50 2621040606 116S1197E 50 2621040612 119S1193E 50 2621040612 119S1193E 50 2621040618 125S1189E 45 2621040700 133S1180E 45 2621040706 142S1168E 45 NNNN