WTXS51 PGTW 060900 WARNING ATCG MIL 26S SIO 210406081852 2021040606 26S SEROJA 008 02 255 09 SATL 060 T000 115S 1189E 050 R050 050 NE QD 035 SE QD 045 SW QD 060 NW QD R034 080 NE QD 065 SE QD 085 SW QD 090 NW QD T012 120S 1178E 050 R050 030 NE QD 010 SE QD 000 SW QD 010 NW QD R034 080 NE QD 080 SE QD 100 SW QD 110 NW QD T024 128S 1163E 055 R050 030 NE QD 020 SE QD 000 SW QD 010 NW QD R034 070 NE QD 100 SE QD 100 SW QD 090 NW QD T036 140S 1148E 060 R050 030 NE QD 020 SE QD 010 SW QD 020 NW QD R034 090 NE QD 100 SE QD 090 SW QD 090 NW QD T048 154S 1132E 065 R064 010 NE QD 015 SE QD 005 SW QD 005 NW QD R050 040 NE QD 030 SE QD 030 SW QD 040 NW QD R034 120 NE QD 130 SE QD 100 SW QD 100 NW QD T072 185S 1107E 090 R064 040 NE QD 040 SE QD 035 SW QD 030 NW QD R050 060 NE QD 060 SE QD 060 SW QD 050 NW QD R034 140 NE QD 150 SE QD 130 SW QD 120 NW QD T096 210S 1094E 105 R064 045 NE QD 050 SE QD 050 SW QD 045 NW QD R050 070 NE QD 070 SE QD 070 SW QD 060 NW QD R034 190 NE QD 140 SE QD 120 SW QD 160 NW QD T120 246S 1103E 095 R064 050 NE QD 050 SE QD 045 SW QD 055 NW QD R050 080 NE QD 070 SE QD 060 SW QD 070 NW QD R034 150 NE QD 140 SE QD 100 SW QD 140 NW QD AMP SUBJ: TROPICAL CYCLONE 26S (SEROJA) WARNING NR 008 1. TROPICAL CYCLONE 26S (SEROJA) WARNING NR 008 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 11.5S 118.9E MOVEMENT PAST SIX HOURS - 255 DEGREES AT 09 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 045 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 080 NM NORTHEAST QUADRANT 065 NM SOUTHEAST QUADRANT 085 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT REPEAT POSIT: 11.5S 118.9E --- FORECASTS: 12 HRS, VALID AT: 061800Z --- 12.0S 117.8E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT 010 NM SOUTHEAST QUADRANT 000 NM SOUTHWEST QUADRANT 010 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 080 NM NORTHEAST QUADRANT 080 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 110 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 240 DEG/ 08 KTS --- 24 HRS, VALID AT: 070600Z --- 12.8S 116.3E MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 000 NM SOUTHWEST QUADRANT 010 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT 100 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 230 DEG/ 09 KTS --- 36 HRS, VALID AT: 071800Z --- 14.0S 114.8E MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 010 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 090 NM NORTHEAST QUADRANT 100 NM SOUTHEAST QUADRANT 090 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 230 DEG/ 10 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 080600Z --- 15.4S 113.2E MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 010 NM NORTHEAST QUADRANT 015 NM SOUTHEAST QUADRANT 005 NM SOUTHWEST QUADRANT 005 NM NORTHWEST QUADRANT 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 - 120 NM NORTHEAST QUADRANT 130 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 215 DEG/ 10 KTS --- 72 HRS, VALID AT: 090600Z --- 18.5S 110.7E MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 140 NM NORTHEAST QUADRANT 150 NM SOUTHEAST QUADRANT 130 NM SOUTHWEST QUADRANT 120 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 205 DEG/ 07 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 100600Z --- 21.0S 109.4E MAX SUSTAINED WINDS - 105 KT, GUSTS 130 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 045 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 070 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 190 NM NORTHEAST QUADRANT 140 NM SOUTHEAST QUADRANT 120 NM SOUTHWEST QUADRANT 160 NM NORTHWEST QUADRANT VECTOR TO 120 HR POSIT: 165 DEG/ 09 KTS --- 120 HRS, VALID AT: 110600Z --- 24.6S 110.3E MAX SUSTAINED WINDS - 095 KT, GUSTS 115 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 050 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 045 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 080 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 150 NM NORTHEAST QUADRANT 140 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 140 NM NORTHWEST QUADRANT --- REMARKS: 060900Z POSITION NEAR 11.6S 118.6E. 06APR21. TROPICAL CYCLONE 26S (SEROJA), LOCATED APPROXIMATELY 429 NM NORTH-NORTHWEST OF BROOME, AUSTRALIA, HAS TRACKED WEST- SOUTHWESTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A DISORGANIZED LOW LEVEL CIRCULATION CENTER (LLCC) WITH PULSING CONVECTION SHEARED TO THE SOUTHWEST OF THE ASSESSED LLCC. DUE TO THE LACK OF RECENT MICROWAVE IMAGERY, THE INITIAL POSITION IS SET WITH ONLY MODERATE CONFIDENCE BASED ON A BLEND OF PGTW, APRF AND KNES FIX POSITIONS AND ANALYSIS OF THE LOW-LEVEL BANDING FEATURES EXPOSED TO THE SOUTH OF THE SYSTEM IN THE ANIMATED VISIBLE IMAGERY. THE INITIAL INTENSITY IS ASSESSED AT 50 KNOTS WITH MODERATE CONFIDENCE BASED ON DVORAK CURRENT INTENSITY ESTIMATES OF T3.5 (55 KTS) FROM PGTW AND APRF, AN ADT ESTIMATE OF T3.2 AND A SATCON ESTIMATE OF 52 KTS. AN EARLIER ASCAT-B AT 060110Z INDICATED A SWATH OF 50-55 KNOT WINDS PRESENT IN THE NORTHEAST AND SOUTHWEST QUADRANTS AND PROVIDED ADDITIONAL SUPPORT TO THE INITIAL INTENSITY ASSESSMENT. ENVIRONMENTAL ANALYSIS REVEALS MARGINAL CONDITIONS, WITH MODERATE TO HIGH (20-25 KTS) EASTERLY VWS AND WEAKLY DIFFLUENT OUTFLOW OFFSET BY VERY WARM (30-31C) SSTS. THE SYSTEM IS CURRENTLY TRACKING WEST-SOUTHWESTWARD ALONG THE NORTHWESTERN PERIPHERY OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTERED OVER WESTERN AUSTRALIA. TC 26S IS FORECAST TO CONTINUE TRACKING SOUTHWESTWARD ALONG THE WESTERN PERIPHERY OF THE STR THROUGH TAU 72. TC 27S WILL APPROACH FROM THE WEST BY ABOUT TAU 48, SWINGING RAPIDLY AROUND THE NORTH THEN NORTHEASTERN PERIPHERY OF TC 26S, IS NOT EXPECTED TO HAVE A SIGNIFICANT IMPACT ON THE OVERALL TRACK FORECAST OF TC 26S AS TC 27S WILL BE THE WEAKER OF THE TWO SYSTEMS AND SHOULD REMAIN FAR ENOUGH DISTANT TO HAVE LITTLE EFFECT. IN THE EXTENDED FORECAST, TC 26S WILL TURN SOUTH THEN SOUTHEASTWARD AFTER TAU 96 IN RESPONSE TO THE APPROACH OF A STRONG MID-LATITUDE TROUGH APPROACHING FROM THE WEST. THE SYSTEM IS EXPECTED TO SLOWLY INTENSIFY THROUGH TAU 48 UNDER MARGINAL ENVIRONMENTAL CONDITIONS. A PERIOD OF MORE RAPID INTENSIFICATION IS EXPECTED BETWEEN TAUS 72 AND 96, PEAKING AT 105 KTS AT TAU 96, AS THE SYSTEM MOVES INTO AN AREA OF DECREASED SHEAR AND TAPS INTO A STRONG POLEWARD OUTFLOW CHANNEL INTO THE BASE OF THE APPROACHING TROUGH. GRADUAL WEAKENING IS EXPECTED THROUGH TAU 120 AS THE SYSTEM MOVES OVER COOLER WATERS AND EXPERIENCES INCREASING SHEAR. NUMERICAL MODEL GUIDANCE IS IS OVERALL GOOD AGREEMENT WITH 92NM SPREAD AT TAU 48 INCREASING TO 150NM AT TAU 120. HOWEVER THERE IS STILL OVERALL LOW CONFIDENCE IN THE JTWC FORECAST TRACK DUE TO THE UNCERTAINTY SURROUNDING THE IMPACT OF THE BINARY INTERACTION WITH TC 27S. 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 113S1198E 55 2621040600 113S1198E 55 2621040606 115S1189E 50 2621040606 115S1189E 50 NNNN