Subject: Indian-S: 01 Active Tropical Cyclone In Southern Hemisphere

From: SIU Weather Processor <[email-masked]>
Date: Thu, 3 Dec 1998 03:01:56 -0600

659
WTXS31 PGTW 030900
1. TROPICAL CYCLONE 05S WARNING NR 003
   01 ACTIVE TROPICAL CYCLONE IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   030600Z9 --- NEAR 17.0S8 118.1E1
     MOVEMENT PAST SIX HOURS - 280 DEGREES AT 06 KTS
     POSITION ACCURATE TO WITHIN 060 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   RADIUS OF 035 KT WINDS - 060 NM SOUTH SEMICIRCLE
                            040 NM ELSEWHERE
   REPEAT POSIT: 17.0S8 118.1E1
    ---
   FORECASTS:
   12 HRS, VALID AT:
   031800Z2 --- 16.9S6 117.1E0
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   RADIUS OF 035 KT WINDS - 060 NM SOUTH SEMICIRCLE
                            040 NM ELSEWHERE
   VECTOR TO 24 HR POSIT: 255 DEG/ 06 KTS
    ---
   24 HRS, VALID AT:
   040600Z0 --- 17.2S0 115.9E6
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   RADIUS OF 035 KT WINDS - 065 NM SOUTH SEMICIRCLE
                            055 NM ELSEWHERE
   VECTOR TO 36 HR POSIT: 235 DEG/ 07 KTS
    ---
   36 HRS, VALID AT:
   041800Z3 --- 18.0S9 114.6E2
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   RADIUS OF 035 KT WINDS - 065 NM SOUTHEAST SEMICIRCLE
                            055 NM ELSEWHERE
   VECTOR TO 48 HR POSIT: 225 DEG/ 09 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   050600Z1 --- 19.2S2 113.3E8
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   VECTOR TO 72 HR POSIT: 205 DEG/ 08 KTS
    ---
   72 HRS, VALID AT:
   060600Z2 --- 22.0S4 111.8E1
   MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
030900Z2 POSITION NEAR 17.0S8  117.8E7.
TROPICAL CYCLONE 05S HAS BEGUN TRACKING WESTWARD AT 6 KNOTS DURING
THE PAST 6 HOURS. THE WARNING POSITION IS BASED UPON AN EARLIER
030038Z4 MICROWAVE IMAGER PASS AND 030530Z1 VISIBLE SATELLITE
IMAGERY. THE WARNING INTENSITY IS BASED UPON SATELLITE CURRENT
INTENSITY ESTIMATES OF 35 KNOTS AND PREVIOUS SUPPORTING SHIP
REPORTS. ANIMATED VISIBLE AND INFRARED SATELLITE IMAGERY INDICATE A
SIGNIFICANTLY MORE WESTWARD TRACK THAN THAT OF THE PREVIOUS
FORECAST. WEAKENED STEERING FLOW AND THE SYSTEM=S ASYMMETRIC
STRUCTURE MAY BE RESPONSIBLE FOR THE SUDDEN TRACK CHANGE AND SLOWER
MOVEMENT. TROPICAL CYCLONE 05S IS LOCATED BETWEEN THE SUBTROPICAL
RIDGE TO ITS SOUTHEAST AND AN APPROACHING TROUGH TO ITS SOUTHWEST,
CAUSING THE AFOREMENTIONED WEAKENED STEERING FLOW. TROPICAL CYCLONE
05S IS FORECAST TO CONTINUE ON THIS WESTWARD TRACK OVER THE NEXT 12
HOURS UNTIL RETURNING TO A MORE DOMINANT STEERING FLOW AHEAD OF THE
TROUGH, RESULTING IN A MORE SOUTHWESTWARD TRACK AFTER THE 24 HOURS
FORECAST POSITION. TROPICAL CYCLONE 05S IS EXPECTED TO BEGIN TO
UNDERGO INCREASING SHEAR AS THE DOMINANT STEERING FLOW REINSTATES.
THEREFORE, TROPICAL CYCLONE 05S IS FORECAST TO STRENGTHEN ONLY
SLIGHTLY THROUGHOUT THE 36 HOUR FORECAST PERIOD, THEN IS EXPECTED TO
BEGIN TO DISSIPATE OVER WATER THROUGHOUT THE REMAINDER OF THE
FORECAST PERIOD. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 030600Z IS 14
FEET. REFER TO WWIO30 PGFW FOR ADDITIONAL SEA HEIGHT INFORMATION.
NEXT WARNINGS AT 031500Z9 (DTG 031351Z3), 032100Z6 (DTG 031951Z9),
040300Z7 (DTG 040151Z1) AND 040900Z3 (DTG 040751Z7).//

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