WTXS51 PGTW 110900 WARNING ATCG MIL 26S SIO 210411071047 2021041106 26S SEROJA 028 01 145 23 SATL RADR 030 T000 261S 1120E 070 R064 030 NE QD 030 SE QD 020 SW QD 020 NW QD R050 050 NE QD 045 SE QD 030 SW QD 040 NW QD R034 125 NE QD 110 SE QD 055 SW QD 090 NW QD T012 302S 1165E 055 R050 040 NE QD 030 SE QD 020 SW QD 040 NW QD R034 110 NE QD 080 SE QD 040 SW QD 090 NW QD T024 347S 1233E 040 R034 100 NE QD 070 SE QD 000 SW QD 070 NW QD AMP 012HR BECOMING EXTRATROPICAL 024HR EXTRATROPICAL SUBJ: TROPICAL CYCLONE 26S (SEROJA) WARNING NR 028 1. TROPICAL CYCLONE 26S (SEROJA) WARNING NR 028 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 110600Z --- NEAR 26.1S 112.0E MOVEMENT PAST SIX HOURS - 145 DEGREES AT 23 KTS POSITION ACCURATE TO WITHIN 030 NM POSITION BASED ON EYE FIXED BY A COMBINATION OF SATELLITE AND RADAR PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 125 NM NORTHEAST QUADRANT 110 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT REPEAT POSIT: 26.1S 112.0E --- FORECASTS: 12 HRS, VALID AT: 111800Z --- 30.2S 116.5E MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING EXTRATROPICAL RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 110 NM NORTHEAST QUADRANT 080 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 130 DEG/ 36 KTS --- 24 HRS, VALID AT: 120600Z --- 34.7S 123.3E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY EXTRATROPICAL RADIUS OF 034 KT WINDS - 100 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 000 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT --- REMARKS: 110900Z POSITION NEAR 27.1S 113.1E. 11APR21. TROPICAL CYCLONE 26S (SEROJA), LOCATED APPROXIMATELY 255 NM SOUTH-SOUTHWEST OF LEARMONTH, AUSTRALIA, HAS TRACKED SOUTHEASTWARD AT 23 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY INDICATES TIGHTLY CURVED CONVECTIVE BANDING WRAPPING INTO A WEAK EYE FEATURE. A 110630Z GMI 89GHZ MICROWAVE IMAGE REVEALS A COMPACT CORE WITH DEEP CONVECTION WRAPPING AROUND THREE QUARTERS OF THE CIRCULATION AND A WELL DEFINED 7NM WIDE MICROWAVE EYE FEATURE. THE EYE FEATURE WAS ALSO EVIDENT IN ANIMATED RADAR DATA FROM THE CARNARVON AIRPORT RADAR SITE. THE COMBINATION OF THE DATA CONFIRMING THE EYE FEATURE SEEN IN THE RADAR, VISIBLE AND MICROWAVE IMAGERY LENT HIGH CONFIDENCE TO THE INITIAL POSITION. THE INITIAL INTENSITY IS SET AT 70 KNOTS WITH MODERATE CONFIDENCE, SLIGHTLY LOWER THAN THE MULTI-AGENCY DVORAK INTENSITY ESTIMATES OF T4.5 (77 KTS) FROM BOTH PGTW AND APRF, AND KNES AT T5.0 (90 KTS). ADT WAS SIGNIFICANTLY LOWER AT T3.1, BUT THE PRESENCE OF THE MICROWAVE AND RADAR EYE PROVIDED STRONG SUPPORT FOR AN INCREASE IN THE INTENSITY OVER THE PREVIOUS SIX HOUR ANALYSIS. TC 26S IS CONTINUING TO ACCELERATE SOUTHEASTWARD ALONG THE WESTERN PERIPHERY OF A DEEP STR LOCATED TO THE EAST AND WILL CONTINUE THIS MOTION THROUGH THE DURATION OF THE FORECAST PERIOD. TC 26S IS EXPECTED TO MAKE LANDFALL NEAR GERALDTON, AUSTRALIA WITHIN THE NEXT 6-8 HOURS BEFORE CONTINUING SOUTHEAST INTO THE GREAT AUSTRALIAN BIGHT. WHILE STILL A TROPICAL CYCLONE, TC 26S IS BEGINNING TO SHOW SOME SIGNS OF INTERACTION WITH THE DRIER, COOLER AIRMASS ENTRENCHED TO THE SOUTHWEST AND IS EXPECTED TO BEGIN EXTRA-TROPICAL TRANSITION (ETT) IMMINENTLY. AS IT MOVES OVER LAND THROUGH TAU 12, THE SYSTEM WILL COMPLETE ETT NO LATER THAN TAU 24 AS IT BECOMES EMBEDDED WITHIN THE DEEP WESTERLIES AND DEVELOPS FRONTAL CHARACTERISTICS. THE SYSTEM HAS LIKELY REACHED PEAK INTENSITY AND WILL SLOWLY WEAKEN PRIOR TO LANDFALL DUE TO RAPIDLY INCREASING VWS AND DECREASING SSTS. ONCE OVER LAND, THE INFLUENCE OF TERRAIN AND VERY HIGH SHEAR VALUES WILL RAPIDLY WEAKEN THE SYSTEM AS IT UNDERGOES ETT. DYNAMIC MODEL GUIDANCE IS IN VERY GOOD AGREEMENT LENDING HIGH CONFIDENCE TO THE JTWC FORECAST TRACK. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 110600Z IS 30 FEET. NEXT WARNINGS AT 111500Z, 112100Z AND 120300Z.// 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 2621040712 151S1156E 45 2621040718 158S1140E 45 2621040800 163S1125E 55 2621040800 163S1125E 55 2621040806 171S1119E 55 2621040806 171S1119E 55 2621040812 175S1115E 50 2621040812 175S1115E 50 2621040818 184S1110E 45 2621040900 190S1101E 45 2621040906 196S1095E 55 2621040912 200S1089E 60 2621040912 200S1089E 60 2621040918 203S1085E 60 2621040918 203S1085E 60 2621041000 206S1082E 55 2621041000 206S1082E 55 2621041006 209S1082E 60 2621041006 209S1082E 60 2621041012 216S1088E 65 2621041012 216S1088E 65 2621041018 227S1096E 65 2621041018 227S1096E 65 2621041018 227S1096E 65 2621041100 242S1105E 65 2621041100 242S1105E 65 2621041100 242S1105E 65 2621041106 261S1120E 70 2621041106 261S1120E 70 2621041106 261S1120E 70 NNNN