WTXS31 PGTW 111500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 26S (SEROJA) WARNING NR 029//
RMKS/
1. TROPICAL CYCLONE 26S (SEROJA) WARNING NR 029    
   01 ACTIVE TROPICAL CYCLONE IN SOUTHIO
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   111200Z --- NEAR 28.3S 114.4E
     MOVEMENT PAST SIX HOURS - 135 DEGREES AT 31 KTS
     POSITION ACCURATE TO WITHIN 020 NM
     POSITION BASED ON EYE FIXED BY A COMBINATION OF 
     SATELLITE, RADAR AND SYNOPTIC DATA
   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
                            025 NM SOUTHEAST QUADRANT
                            020 NM SOUTHWEST QUADRANT
                            020 NM NORTHWEST QUADRANT
   RADIUS OF 050 KT WINDS - 065 NM NORTHEAST QUADRANT
                            060 NM SOUTHEAST QUADRANT
                            030 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 115 NM NORTHEAST QUADRANT
                            100 NM SOUTHEAST QUADRANT
                            055 NM SOUTHWEST QUADRANT
                            090 NM NORTHWEST QUADRANT
   REPEAT POSIT: 28.3S 114.4E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   120000Z --- 32.4S 119.8E
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   BECOMING EXTRATROPICAL
   VECTOR TO 24 HR POSIT: 125 DEG/ 33 KTS
    ---
   24 HRS, VALID AT:
   121200Z --- 36.2S 126.2E
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   EXTRATROPICAL
    ---
REMARKS:
111500Z POSITION NEAR 29.3S 115.8E.
11APR21. TROPICAL CYCLONE 26S (SEROJA), LOCATED APPROXIMATELY 360
NM SOUTH OF LEARMONTH, AUSTRALIA, HAS TRACKED SOUTHEASTWARD AT 31
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) 
SATELLITE IMAGERY DEPICTS A WELL DEFINED 10 NM EYE FEATURE JUST 
CROSSING THE SHORELINE NEAR PORT GREGORY, AUSTRALIA AT THE 111200Z 
HOUR. SURFACE OBSERVATIONS FROM THE REGION, THE EIR EYE FEATURE AND 
A WELL-DEFINED RADAR EYE COMBINED TO LEND HIGH CONFIDENCE TO THE 
INITIAL POSITION. THE INITIAL INTENSITY IS ASSESSED AT 70 KTS WITH 
HIGH CONFIDENCE, HEDGED SLIGHTLY LOWER THAN THE AVERAGE OF MULTI-
AGENCY DVORAK INTENSITY ESTIMATES OF T4.5 (77 KTS) FROM PGTW AND 
APRF, BASED ON ANALYSIS OF SURFACE PRESSURE READINGS NEAR 976 MB 
FROM NEARBY OBSERVATION SITES WHICH SUPPORT AN INTENSITY IN THE 65-
70 KNOT RANGE. PEAK WIND GUSTS OF 65 KTS AT THE GERALDTON AIRPORT 
PROVIDES ADDITIONAL SUPPORT TO THE INITIAL INTENSITY. TC 26S IS 
BEING STEERED RAPIDLY TOWARDS THE SOUTHEAST ALONG THE GRADIENT 
BETWEEN A DEEP-LAYER STR TO THE NORTHEAST AND AN APPROACHING MID-
LATITUDE TROUGH TO THE SOUTHWEST. AS THE SYSTEM RACES SOUTHEAST OVER 
INLAND AUSTRALIA IT IS EXPECTED TO RAPIDLY WEAKEN DUE TO INCREASING 
SHEAR AND TERRAIN INTERACTION. THE SIMULTANEOUS DEVELOPMENT OF DRY 
AIR ENTRAINMENT AND THERMAL ADVECTION WILL SIGNAL THE COMMENCEMENT 
OF EXTRA-TROPICAL TRANSITION (ETT) WITHIN THE NEXT 6-12 HOURS, WITH 
FULL TRANSITION EXPECTED NO LATER THAN TAU 24, LIKELY BY TAU 18, 
ALONG THE COAST OF SOUTHERN AUSTRALIA. DYNAMIC MODEL GUIDANCE IS IN 
VERY GOOD AGREEMENT, LENDING HIGH CONFIDENCE TO THE JTWC FORECAST 
TRACK. THIS IS THE FINAL WARNING ON THIS SYSTEM BY THE JOINT TYPHOON 
WRNCEN PEARL HARBOR HI. THE SYSTEM WILL BE CLOSELY MONITORED FOR 
SIGNS OF REGENERATION. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 111200Z IS 
28 FEET.//
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