WTXS31 PGTW 082100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 26S (SEROJA) WARNING NR 018// RMKS/ 1. TROPICAL CYCLONE 26S (SEROJA) WARNING NR 018 02 ACTIVE TROPICAL CYCLONES IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 081800Z --- NEAR 18.4S 111.0E MOVEMENT PAST SIX HOURS - 210 DEGREES AT 10 KTS POSITION ACCURATE TO WITHIN 020 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 - 075 NM NORTHEAST QUADRANT 075 NM SOUTHEAST QUADRANT 000 NM SOUTHWEST QUADRANT 000 NM NORTHWEST QUADRANT REPEAT POSIT: 18.4S 111.0E --- FORECASTS: 12 HRS, VALID AT: 090600Z --- 19.2S 109.8E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 080 NM SOUTHEAST QUADRANT 080 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 110 NM NORTHEAST QUADRANT 100 NM SOUTHEAST QUADRANT 090 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 225 DEG/ 05 KTS --- 24 HRS, VALID AT: 091800Z --- 19.9S 109.0E MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 020 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 015 NM SOUTHWEST QUADRANT 015 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 080 NM SOUTHEAST QUADRANT 080 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 110 NM NORTHEAST QUADRANT 100 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 195 DEG/ 04 KTS --- 36 HRS, VALID AT: 100600Z --- 20.6S 108.8E 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 015 NM SOUTHWEST QUADRANT 015 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 090 NM SOUTHEAST QUADRANT 090 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 110 NM NORTHEAST QUADRANT 100 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 160 DEG/ 09 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 101800Z --- 22.3S 109.5E MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 020 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 015 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 090 NM SOUTHEAST QUADRANT 090 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 110 NM NORTHEAST QUADRANT 100 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 140 DEG/ 18 KTS --- 72 HRS, VALID AT: 111800Z --- 28.0S 114.6E MAX SUSTAINED WINDS - 080 KT, GUSTS 100 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 020 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 000 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 090 NM SOUTHEAST QUADRANT 090 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 120 NM NORTHEAST QUADRANT 110 NM SOUTHEAST QUADRANT 110 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 125 DEG/ 32 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 121800Z --- 35.3S 127.2E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING EXTRATROPICAL RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 080 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT VECTOR TO 120 HR POSIT: 130 DEG/ 29 KTS --- 120 HRS, VALID AT: 131800Z --- 41.9S 139.3E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY EXTRATROPICAL --- REMARKS: 082100Z POSITION NEAR 18.6S 110.7E. 08APR21. TROPICAL CYCLONE (TC) 26S (SEROJA), LOCATED APPROXIMATELY 292 NM NORTHWEST OF LEARMONTH, AUSTRALIA, HAS TRACKED SOUTH- SOUTHWESTWARD AT 10 KTS OVER THE PAST SIX HOURS. THE CYCLONE HAS ATTAINED A MORE SYMMETRICAL APPEARANCE ON ENHANCED INFRARED SATELLITE IMAGERY TODAY, AS VERTICAL SHEAR HAS LESSENED SIGNIFICANTLY, AND CONVECTIVE BANDING HAS EXPANDED INTO THE EASTERN SEMICIRCLE, AS ANTICIPATED YESTERDAY. THE CONVECTIVE MODE HAS EVOLVED FROM THE LARGE BLOB ON THE WEST SIDE YESTERDAY TO A SYMMETRICAL BANDING PATTERN TODAY, WITH A TREND TOWARD INCREASING CONVECTIVE COVERAGE OVER THE INNER CORE DURING THE LAST 3 HOURS. THE CYCLONE HAS NOT YET INTENSIFIED, AND IN FACT MAX WINDS HAVE DECREASED TO 45 KT BASED ON AN 081141Z ASCAT PASS AND SATELLITE ESTIMATES OF 43 KT FROM SATCON AND A 081800Z T3.0 FIX FROM PGTW. THE SURROUNDING ENVIRONMENT IS HIGHLY FAVORABLE WITH SEA SURFACE TEMPERATURES OF 30C AND VERTICAL SHEAR LESS THAN 10 KT. HEALTHY RADIAL CIRRUS OUTFLOW IS OBSERVED IN ALL QUADRANTS EXCEPT SOUTHEAST. TC 26S IS EXPECTED TO CONTINUE TRACKING SOUTHWESTWARD DURING THE NEXT 24 HOURS AS IT ROUNDS THE PERIPHERY OF A DEEP-LAYER RIDGE OVER WESTERN AUSTRALIA. THE FORECAST HAS BEEN ADJUSTED A BIT WESTWARD AND SLOWER THROUGH 36 HOURS ALONG THE WESTERN SIDE OF THE MODEL GUIDANCE ENVELOPE. THIS IS DUE TO BINARY INTERACTION WITH TC 27S THAT APPEARS TO BE TUGGING TC 26S A BIT MORE TO THE WEST THAN RECENT MODEL RUNS ANTICIPATED, POSSIBLY DUE TO TC 26S BEING WEAKER THAN EXPECTED TODAY. AFTER 36 HOURS, AN ACCELERATION SOUTHWARD AND THEN SOUTHEASTWARD IS EXPECTED AS AN UPPER LEVEL MID-LATITUDE TROUGH MOVES OVER SOUTHWESTERN AUSTRALIA AND GUIDES TC 26S ACROSS THE CONTINENT AND INTO THE AUSTRALIAN BIGHT. LANDFALL IS EXPECTED JUST BEFORE THE 72-HOUR FORECAST POINT WITHIN 40 NM OF GERALDTON, AUSTRALIA. THE INTENSITY FORECAST HAS BEEN ADJUSTED LOWER BASED ON THE DELAYED ONSET OF EXPECTED INTENSIFICATION. HOWEVER, A PERIOD OF RAPID INTENSIFICATION IS STILL EXPECTED BETWEEN 12 AND 36 HOURS, AS THE CYCLONE HAS ACHIEVED AN ORGANIZED, SYMMETRIC STRUCTURE AND IS EMBEDDED IN A FAVORABLE ENVIRONMENT. THE CYCLONE IS FORECAST TO SLOW DOWN WHILE PASSING WEST OF THE 20S, 110E POINT, WHICH ROUGHLY MARKS THE SOUTHWESTERN EDGE OF DEEPLY WARM WATER. THE RESULTING INCREASE IN UPWELLING OF COOLER WATER COULD LIMIT THE PEAK INTENSITY DURING THE 36-48 HOUR PERIOD. HIGH-RESOLUTION TC MODELS HWRF AND CTCX EXPECT A PEAK INTENSITY OF 95-105 KTS. HOWEVER, THEY SEEM TO INTENSITY TOO QUICKLY IN THE FIRST 12 HOURS, SO THE PEAK INTENSITY FORECAST IS SET LOWER AT 90 KT AROUND 48 HOURS. THE CYCLONE IS EXPECTED TO MAINTAIN INTENSITY OR SLIGHTLY WEAKEN ON APPROACH TO LANDFALL NEAR GERALDTON, AUSTRALIA, AS SEA SURFACE TEMPERATURES REMAIN 27-28C NEAR THE COASTLINE AND VERTICAL SHEAR WILL NOT ATTAIN HOSTILE VALUES UNTIL JUST BEFORE LANDFALL. THE EXACT TIMING OF LANDFALL HAS ABOVE-AVERAGE UNCERTAINTY DUE TO UNCERTAINTY IN HOW MUCH TC 26S WILL BE SLOWED DOWN BY INTERACTION WITH TC 27S PRIOR TO MAKING ITS SOUTHEASTWARD MOVE TOWARD THE COAST. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 081800Z IS 21 FEET. NEXT WARNINGS AT 090300Z, 090900Z, 091500Z AND 092100Z. REFER TO TROPICAL CYCLONE 27S (TWENTYSEVEN) WARNINGS (WTXS32 PGTW) FOR SIX-HOURLY UPDATES. // NNNN