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Tropical Cyclone SELWYN : JTWC Advisories
Season 1997-1998 Summaries (Operational Data): [AU] [SIO] [SPAC] [SH]
---> Tropical Cyclone SELWYN Track Map and Data

WTXS22 PGTW 971226 14:30z
SUBJ/TROPICAL CYCLONE FORMATION ALERT 261423Z DEC 97//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
A 170 NM RADIUS OF 13.6S0 112.5E9 WITHIN THE NEXT 12 TO 24 HOURS.
AVAILABLE DATA DOES NOT JUSTIFY ISSUANCE OF NUMBERED TROPICAL
CYCLONE WARNINGS AT THIS TIME. WINDS IN THE AREA ARE ESTIMATED TO
BE 15 TO 25 KNOTS. METSAT IMAGERY AT 261200Z INDICATES THAT A
CIRCULATION CENTER IS LOCATED NEAR 12.8S1 112.2E6.  THE SYSTEM IS
MOVING SOUTH-SOUTHEASTWARD AT 04 KNOTS.
2. REMARKS:
A SCATTEROMETER PASS FROM 261529Z5 INDICATED THAT THE LOW LEVEL
CIRCULATION CENTER IN THE SOUTHEAST INDIAN OCEAN HAD WINDS OF
15 TO 25 KNOTS. ALTHOUGH CONVECTION HAS BEEN LOCATED TO THE WEST
OF THE LOW LEVEL CIRCULATION CENTER DURING MUCH OF THE DAY, RECENT
SATELLITE DATA INDICATES THAT CONVECTION IS STARTING TO FORM CLOSER
TOWARDS THE CENTER. SYNOPTIC CONDITIONS ARE FAVORABLE FOR DEVELOPMENT
TO COMMENCE WITHIN THE NEXT 12 TO 24 HOURS.
3. THIS ALERT VALID UNTIL 271430Z7.//
=========================================================================
WTXS32 PGTW 971227 03:00z
THIS WARNING SUPERSEDES AND CANCELS NAVPACMETOCCEN WEST
GU 261423Z DEC 97 TROPICAL CYCLONE FORMATION ALERT
(WTXS22 PGTW 261430)
1. TROPICAL CYCLONE 09S WARNING NR 001
   02 ACTIVE TROPICAL CYCLONES IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   270000Z9 --- 14.6S1 110.8E0
     MOVEMENT PAST SIX HOURS - 225 DEGREES AT 08 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
   REPEAT POSIT: 14.6S1 110.8E0
    ---
   FORECASTS:
   12 HRS, VALID AT:
   271200Z2 --- 15.4S0 109.7E7
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   RADIUS OF 035 KT WINDS - 040 NM SOUTHEAST SEMICIRCLE
                            035 NM ELSEWHERE
   VECTOR TO 24 HR POSIT: 250 DEG/ 07 KTS
    ---
   24 HRS, VALID AT:
   280000Z0 --- 15.9S5 108.4E3
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   RADIUS OF 035 KT WINDS - 050 NM SOUTHEAST SEMICIRCLE
                            040 NM ELSEWHERE
   VECTOR TO 36 HR POSIT: 255 DEG/ 07 KTS
    ---
   36 HRS, VALID AT:
   281200Z3 --- 16.3S0 107.0E8
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   RADIUS OF 035 KT WINDS - 055 NM SOUTHEAST SEMICIRCLE
                            040 NM ELSEWHERE
   VECTOR TO 48 HR POSIT: 250 DEG/ 07 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   290000Z1 --- 16.8S5 105.6E2
   MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
   RADIUS OF 050 KT WINDS - 020 NM
   RADIUS OF 035 KT WINDS - 060 NM SOUTHEAST SEMICIRCLE
                            045 NM ELSEWHERE
    ---
REMARKS:
270300Z2 POSITION 14.8S3  110.5E7
TROPICAL CYCLONE 09S IS MOVING SOUTHWESTWARD AT 8 KNOTS.
THE SYSTEM IS STILL CONSOLIDATING AND DIFFICULT TO
POSITION. THE WARNING POSITION IS BASED ON 262330Z6
VISIBLE SATELLITE IMAGERY. INTENSIFICATION IS EXPECTED TO
BE A SLOWER THAN CLIMATOLOGICAL RATE AS IT CONSOLIDATES.
THE SUBTROPICAL RIDGE LOCATED TO THE SYSTEM=S SOUTH-
SOUTHEAST IS EXPECTED TO CONTINUE TO PROVIDE THE DOMINANT
STEERING INFLUENCE MOVING TC 09C SOUTHWESTWARD THROUGHOUT
THE FORECAST PERIOD. MAXIMUM SIGNIFICANT WAVE HEIGHT AT
270000Z IS 13 FEET. NEXT WARNINGS AT 271500Z5 (DTG
271353Z1) AND 280300Z3 (DTG 280153Z9). THIS WARNING
SUPERSEDES AND CANCELS NAVPACMETOCCEN WEST GU 261423Z DEC
97 TROPICAL CYCLONE FORMATION ALERT (WTXS22 PGTW 261430)
REFER TO TROPICAL CYCLONE 08S (SID) WARNINGS (WTPS31
PGTW) FOR TWELVE-HOURLY UPDATES.//
=========================================================================
WTXS32 PGTW 971227 15:00z
1. TROPICAL CYCLONE 09S (SELWYN) WARNING NR 002
   02 ACTIVE TROPICAL CYCLONES IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   271200Z2 --- 15.2S8 109.9E9
     MOVEMENT PAST SIX HOURS - 230 DEGREES AT 06 KTS
     POSITION ACCURATE TO WITHIN 045 NM
     POSITION BASED ON EYE FIXED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT
   RADIUS OF 050 KT WINDS - 025 NM SOUTHEAST SEMICIRCLE
                            015 NM ELSEWHERE
   RADIUS OF 035 KT WINDS - 050 NM SOUTHEAST SEMICIRCLE
                            035 NM ELSEWHERE
   REPEAT POSIT: 15.2S8 109.9E9
    ---
   FORECASTS:
   12 HRS, VALID AT:
   280000Z0 --- 15.7S3 108.8E7
   MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT
   RADIUS OF 050 KT WINDS - 025 NM SOUTHEAST SEMICIRCLE
                            015 NM ELSEWHERE
   RADIUS OF 035 KT WINDS - 050 NM SOUTHEAST SEMICIRCLE
                            035 NM ELSEWHERE
   VECTOR TO 24 HR POSIT: 245 DEG/ 08 KTS
    ---
   24 HRS, VALID AT:
   281200Z3 --- 16.3S0 107.3E1
   MAX SUSTAINED WINDS - 075 KT, GUSTS 090 KT
   RADIUS OF 050 KT WINDS - 025 NM SOUTHEAST SEMICIRCLE
                            015 NM ELSEWHERE
   RADIUS OF 035 KT WINDS - 055 NM SOUTHEAST SEMICIRCLE
                            040 NM ELSEWHERE
   VECTOR TO 36 HR POSIT: 245 DEG/ 08 KTS
    ---
   36 HRS, VALID AT:
   290000Z1 --- 17.0S8 105.8E4
   MAX SUSTAINED WINDS - 080 KT, GUSTS 100 KT
   RADIUS OF 050 KT WINDS - 025 NM SOUTHEAST SEMICIRCLE
                            015 NM ELSEWHERE
   RADIUS OF 035 KT WINDS - 055 NM SOUTHEAST SEMICIRCLE
                            040 NM ELSEWHERE
   VECTOR TO 48 HR POSIT: 240 DEG/ 08 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   291200Z4 --- 17.9S7 104.3E8
   MAX SUSTAINED WINDS - 085 KT, GUSTS 105 KT
   RADIUS OF 050 KT WINDS - 025 NM SOUTHEAST SEMICIRCLE
                            015 NM ELSEWHERE
   RADIUS OF 035 KT WINDS - 055 NM SOUTHEAST SEMICIRCLE
                            040 NM ELSEWHERE
    ---
REMARKS:
271500Z5 POSITION 15.3S9  109.6E6
TROPICAL CYCLONE 09S (SELWYN) IS MOVING SOUTHWESTWARD AT
06 KNOTS. THE WARNING POSITION IS BASED ON 271036Z9
MICROWAVE IMAGERY (SSM/I). INFRARED IMAGERY SHOW A 7 NM
CLOUD FILLED EYE.  THE WARNING INTENSITY IS BASED ON
A SATELLITE DERIVED INTENSITY ESTIMATE OF CI4.0 (65
KNOTS). THE SYSTEM IS FORECAST TO CONTINUE A
SOUTHWESTWARD TRACK THROUGHOUT THE FORECAST PERIOD
AS THE STEERING IS PROVIDED BY THE SUBTROPICAL RIDGE TO
THE SOUTHEAST. TC 09S (SELWYN) IS EXPECTED TO INTENSITY
VERY SLOWLY DUE TO SHEAR FROM THE NORTHWEST. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 271200Z IS 15 FEET. NEXT
WARNINGS AT 280300Z3 (DTG 280153Z9) AND 281500Z6 (DTG
281353Z2). REFER TO TROPICAL CYCLONE 08S (SID) WARNINGS
(WTPS31 PGTW) FOR TWELVE-HOURLY UPDATES.//
=========================================================================
WTXS32 PGTW 971228 03:00z CORRECTED
1. TROPICAL CYCLONE 09S (SELWYN) WARNING NR 003A
CORRECTED
   02 ACTIVE TROPICAL CYCLONES IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   280000Z0 --- 15.5S1 109.0E0
     MOVEMENT PAST SIX HOURS - 245 DEGREES AT 05 KTS
     POSITION ACCURATE TO WITHIN 060 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
   RADIUS OF 050 KT WINDS - 020 NM
   RADIUS OF 035 KT WINDS - 050 NM SOUTHEAST SEMICIRCLE
                            045 NM ELSEWHERE
   REPEAT POSIT: 15.5S1 109.0E0
    ---
   FORECASTS:
   12 HRS, VALID AT:
   281200Z3 --- 16.0S7 108.1E0
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   RADIUS OF 035 KT WINDS - 040 NM SOUTHEAST SEMICIRCLE
                            035 NM ELSEWHERE
   VECTOR TO 24 HR POSIT: 240 DEG/ 05 KTS
    ---
   24 HRS, VALID AT:
   290000Z1 --- 16.5S2 107.2E0
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   RADIUS OF 035 KT WINDS - 040 NM SOUTHEAST SEMICIRCLE
                            035 NM ELSEWHERE
   VECTOR TO 36 HR POSIT: 240 DEG/ 06 KTS
    ---
   36 HRS, VALID AT:
   291200Z4 --- 17.1S9 106.2E9
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER
WATER
   RADIUS OF 035 KT WINDS - 035 NM SOUTHEAST SEMICIRCLE
                            025 NM ELSEWHERE
   VECTOR TO 48 HR POSIT: 225 DEG/ 06 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   300000Z3 --- 17.9S7 105.3E9
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER
WATER
    ---
REMARKS:
280300Z3 POSITION 15.6S2  108.8E7
TROPICAL CYCLONE 09S (SELWYN) IS MOVING WEST-
SOUTHWESTWARD AT 5 KNOTS. WATER VAPOR IMAGERY INDICATES
THAT THE SYSTEM IS EXPERIENCING SIGNIFICANT COLD DRY AIR
ENTRAINMENT WHICH IS HINDERING CURRENT DEVELOPMENT.
DEPARTING FROM THE INTENSITY FORECAST ISSUED IN OUR LAST
WARNING, TC 09S (SELWYN) IS EXPECTED TO CONTINUE SLOWLY
WEST-SOUTHWESTWARD AND WEAKEN DUE TO THE ENTRAINMENT AND
UPPER-LEVEL VERTICAL WIND SHEAR. MAXIMUM SIGNIFICANT WAVE
HEIGHT AT 280000Z IS 15 FEET. NEXT WARNINGS AT 281500Z6
(DTG 281353Z2) AND 290300Z4 (DTG 290153Z0). REFER TO
TROPICAL CYCLONE 08S (SID) WARNINGS (WTPS31 PGTW) FOR
TWELVE-HOURLY UPDATES. JUSTIFICATION FOR COR: CORRECTED
SYSTEM=S DIRECTION OF MOVEMENT//
=========================================================================
WTXS32 PGTW 971228 15:00z
1. TROPICAL CYCLONE 09S (SELWYN) WARNING NR 004
   02 ACTIVE TROPICAL CYCLONES IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   281200Z3 --- 16.3S0 107.9E7
     MOVEMENT PAST SIX HOURS - 240 DEGREES AT 06 KTS
     POSITION ACCURATE TO WITHIN 045 NM
     POSITION BASED ON EYE FIXED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
   RADIUS OF 050 KT WINDS - 020 NM
   RADIUS OF 035 KT WINDS - 050 NM SOUTHEAST SEMICIRCLE
                            045 NM ELSEWHERE
   REPEAT POSIT: 16.3S0 107.9E7
    ---
   FORECASTS:
   12 HRS, VALID AT:
   290000Z1 --- 16.8S5 106.8E5
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   RADIUS OF 035 KT WINDS - 040 NM SOUTHEAST SEMICIRCLE
                            035 NM ELSEWHERE
   VECTOR TO 24 HR POSIT: 240 DEG/ 07 KTS
    ---
   24 HRS, VALID AT:
   291200Z4 --- 17.5S3 105.6E2
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   RADIUS OF 035 KT WINDS - 040 NM SOUTHEAST SEMICIRCLE
                            035 NM ELSEWHERE
   VECTOR TO 36 HR POSIT: 240 DEG/ 07 KTS
    ---
   36 HRS, VALID AT:
   300000Z3 --- 18.2S1 104.3E8
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER
WATER
   RADIUS OF 035 KT WINDS - 035 NM SOUTHEAST SEMICIRCLE
                            025 NM ELSEWHERE
   VECTOR TO 48 HR POSIT: 240 DEG/ 07 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   301200Z6 --- 18.9S8 103.1E5
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER
WATER
    ---
REMARKS:
281500Z6 POSITION 16.4S1  107.6E4
TROPICAL CYCLONE 09S (SELWYN) IS MOVING WEST-
SOUTHWESTWARD AT 06 KNOTS. THE WARNING POSITION AND
INTENSITY ARE BASED ON 281130Z5 INFRARED SATELLITE
IMAGERY. THE SYSTEM IS EXPECTED TO WEAKEN AS IT
ENCOUNTERS CONTINUE UPPER-LEVEL WINDS SHEAR. TC 09S
(SELWYN) IS FORECAST TO CONTINUE A WEST-SOUTHWESTWARD
TRACK THROUGHOUT THE FORECAST PERIOD. MAXIMUM SIGNIFICANT
WAVE HEIGHT AT 281200Z IS 15 FEET. NEXT WARNINGS AT
290300Z4 (DTG 290153Z0) AND 291500Z7 (DTG 291353Z3).
REFER TO TROPICAL CYCLONE 08S (SID) WARNING 06 (WTPS31
PGTW) FOR FINAL WARNING.//
=========================================================================
WTXS32 PGTW 971229 03:00z
1. TROPICAL CYCLONE 09S (SELWYN) WARNING NR 005
   01 ACTIVE TROPICAL CYCLONE IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   290000Z1 --- 17.6S4 107.0E8
     MOVEMENT PAST SIX HOURS - 215 DEGREES AT 08 KTS
     POSITION ACCURATE TO WITHIN 060 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
   RADIUS OF 050 KT WINDS - 025 NM
   RADIUS OF 035 KT WINDS - 050 NM SOUTHEAST SEMICIRCLE
                            045 NM ELSEWHERE
   REPEAT POSIT: 17.6S4 107.0E8
    ---
   FORECASTS:
   12 HRS, VALID AT:
   291200Z4 --- 18.8S7 106.3E0
   MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
   RADIUS OF 050 KT WINDS - 020 NM
   RADIUS OF 035 KT WINDS - 045 NM SOUTHEAST SEMICIRCLE
                            040 NM ELSEWHERE
   VECTOR TO 24 HR POSIT: 220 DEG/ 07 KTS
    ---
   24 HRS, VALID AT:
   300000Z3 --- 19.9S9 105.4E0
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   RADIUS OF 035 KT WINDS - 040 NM SOUTHEAST SEMICIRCLE
                            035 NM ELSEWHERE
   VECTOR TO 36 HR POSIT: 255 DEG/ 07 KTS
    ---
   36 HRS, VALID AT:
   301200Z6 --- 20.3S5 104.0E5
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   RADIUS OF 035 KT WINDS - 035 NM SOUTH SEMICIRCLE
                            025 NM ELSEWHERE
   VECTOR TO 48 HR POSIT: 265 DEG/ 07 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   310000Z4 --- 20.4S6 102.5E8
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER
WATER
    ---
REMARKS:
290300Z4 POSITION 17.9S7  106.8E5
TROPICAL CYCLONE 09S (SELWYN) IS MOVING SOUTHWEST AT 8
KNOTS. THE SYSTEM IS CONTINUING TO SHOW SOME SIGNS OF
COLD AIR ENTRAINMENT AND UPPER LEVEL VERTICAL WIND SHEAR,
BUT HAS MAINTAINED A HIGH INTENSITY OVER THE PAST 24
HOURS. THE SYSTEM IS FORECAST TO MOVE INTO AN ENVIRONMENT
OF INCREASED VERTICAL WIND SHEAR WITHIN THE NEXT 12 TO 36
HOURS, CAUSING IT TO WEAKEN CONSIDERABLY. AS TC 09S
(SELWYN) SHEARS, THE LOW-LEVEL CIRCULATION IS EXPECTED TO
TRACK WESTWARD. MAXIMUM SIGNIFICANT WAVE HEIGHT AT
290000Z IS 15 FEET. NEXT WARNINGS AT 291500Z7 (DTG
291353Z3) AND 300300Z6 (DTG 300153Z2).//
=========================================================================
WTXS32 PGTW 971229 15:00z
1. TROPICAL CYCLONE 09S (SELWYN) WARNING NR 006
   01 ACTIVE TROPICAL CYCLONE IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   291200Z4 --- 18.1S0 104.1E6
     MOVEMENT PAST SIX HOURS - 250 DEGREES AT 13 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
   RADIUS OF 035 KT WINDS - 050 NM SOUTHEAST SEMICIRCLE
                            045 NM ELSEWHERE
   REPEAT POSIT: 18.1S0 104.1E6
    ---
   FORECASTS:
   12 HRS, VALID AT:
   300000Z3 --- 18.9S8 102.1E4
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   RADIUS OF 035 KT WINDS - 045 NM SOUTHEAST SEMICIRCLE
                            040 NM ELSEWHERE
   VECTOR TO 24 HR POSIT: 255 DEG/ 10 KTS
    ---
   24 HRS, VALID AT:
   301200Z6 --- 19.4S4 100.1E2
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   RADIUS OF 035 KT WINDS - 040 NM SOUTHEAST SEMICIRCLE
                            035 NM ELSEWHERE
   VECTOR TO 36 HR POSIT: 255 DEG/ 10 KTS
    ---
   36 HRS, VALID AT:
   310000Z4 --- 19.8S8 98.3E0
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   RADIUS OF 035 KT WINDS - 035 NM SOUTH SEMICIRCLE
                            025 NM ELSEWHERE
   VECTOR TO 48 HR POSIT: 260 DEG/ 10 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   311200Z7 --- 20.2S4 96.1E6
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER
WATER
    ---
REMARKS:
291500Z7 POSITION 18.3S2  103.6E0
TROPICAL CYCLONE 09S (SELWYN) IS MOVING WEST-
SOUTHWESTWARD AT 13 KNOTS. THE SYSTEM IS EXPECTED TO SLOW
AND TAKE ON A SLIGHTLY MORE WESTWARD MOTION DURING THE
FORECAST PERIOD. WE BELIEVE THAT THE DOMINANT STEERING
FLOW ON 09S (SELWYN) WILL BE THE EASTERLIES EQUATORWARD
OF THE LOWER TROPOSPHERIC (850 MB) SUBTROPICAL RIDGE. THE
WARNING POSITION AND INTENSITY ARE BASED ON 291130Z6
INFRARED SATELLITE IMAGERY. TC 09S (SELWYN) IS FORECAST
TO WEAKEN DUE TO MODERATE TO HEAVY UPPER LEVEL WIND SHEAR
FROM THE NORTHWEST. MAXIMUM SIGNIFICANT WAVE HEIGHT AT
291200Z4 IS 15 FEET. NEXT WARNINGS AT 300300Z6 (DTG
300153Z2) AND 301500Z9 (DTG 301353Z5).//
=========================================================================
WTXS32 PGTW 971230 03:00z
1. TROPICAL CYCLONE 09S (SELWYN) WARNING NR 007
   01 ACTIVE TROPICAL CYCLONE IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   300000Z3 --- 17.1S9 103.0E4
     MOVEMENT PAST SIX HOURS - 290 DEGREES AT 09 KTS
     POSITION ACCURATE TO WITHIN 045 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   RADIUS OF 035 KT WINDS - 050 NM NORTHEAST SEMICIRCLE
                            040 NM ELSEWHERE
   REPEAT POSIT: 17.1S9 103.0E4
    ---
   FORECASTS:
   12 HRS, VALID AT:
   301200Z6 --- 16.4S1 101.3E5
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER
WATER
   VECTOR TO 24 HR POSIT: 300 DEG/ 09 KTS
    ---
   24 HRS, VALID AT:
   310000Z4 --- 15.5S1 99.8E6
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER
WATER
    ---
REMARKS:
300300Z6 POSITION 16.9S6  102.6E9
TROPICAL CYCLONE 09S (SELWYN) IS MOVING WEST-
NORTHWESTWARD AT 09 KNOTS.  THE WARNING POSITION IS BASED
UPON 292330Z9 VISIBLE SATELLITE IMAGERY.  CURRENTLY, THE
SYSTEM IS WEAKENING DUE TO VERTICAL WIND SHEAR WITH THE
NEAREST DEEP CONVECTION LOCATED APPROXIMATELY 100NM
SOUTHEAST OF THE CENTER.  THE WARNING INTENSITY IS BASED
UPON A SATELLITE INTENSITY ESTIMATE OF 45 KNOTS.
TROPICAL CYCLONE 09S (SELWYN) SHOULD WEAKEN THROUGHOUT
THE FORECAST PERIOD AS VERTICAL WIND SHEAR IS EXPECTED TO
CONTINUE ACROSS THE CENTER.  THE FORECAST TRACK HAS BEEN
SHIFTED SLIGHTLY NORTH OF THE PREVIOUS WARNING TO REFLECT
THE MORE RECENT WEST-NORTHWESTWARD MOTION OF THE SYSTEM.
THE SYSTEM SHOULD MOVE WEST-NORTHWESTWARD FOR THE ENTIRE
FORECAST PERIOD DUE TO THE LOW LEVEL EAST-SOUTHEASTERLY
FLOW FROM HIGH PRESSURE LOCATED SOUTH OF THE CENTER.
MAXIMUM SIGNIFICANT WAVE HEIGHT AT 300000Z IS 13 FEET.
NEXT WARNING AT 301500Z9 (DTG 301353Z5).//
=========================================================================
WTXS32 PGTW 971230 15:00z
1. TROPICAL CYCLONE 09S (SELWYN) WARNING NR 008
   01 ACTIVE TROPICAL CYCLONE IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   301200Z6 --- 16.4S1 101.1E3
     MOVEMENT PAST SIX HOURS - 295 DEGREES AT 10 KTS
     POSITION ACCURATE TO WITHIN 060 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   RADIUS OF 035 KT WINDS - 050 NM NORTHEAST SEMICIRCLE
                            040 NM ELSEWHERE
   REPEAT POSIT: 16.4S1 101.1E3
    ---
   FORECASTS:
   12 HRS, VALID AT:
   310000Z4 --- 15.6S2 99.2E0
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER
WATER
   VECTOR TO 24 HR POSIT: 285 DEG/ 09 KTS
    ---
   24 HRS, VALID AT:
   311200Z7 --- 15.1S7 97.4E0
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER
WATER
    ---
REMARKS:
301500Z9 POSITION 16.2S9  100.6E7
TROPICAL CYCLONE 09S (SELWYN) CONTINUES TO MOVE TOWARDS
THE WEST-NORTHWEST AND HAS INCREASED ITS FORWARD SPEED
SLIGHTLY TO 10 KNOTS. THE WARNING POSITION AND INTENSITY
ARE BASED ON 301130Z8 INFRARED SATELLITE IMAGERY.
ANIMATED INFRARED IMAGERY SHOWS THE CONVECTION ASSOCIATED
WITH TC 09S HAS INCREASED SLIGHTLY OVER THE PAST 6 HOURS.
HOWEVER, THE LOW-LEVEL CIRCULATION REMAINS APPROXIMATELY
40NM AWAY FROM THE CLOSEST DEEP CONVECTION. THE FORECAST
TRACK REMAINS SIMILAR AS TROPICAL CYCLONE 09S (SELWYN) IS
EXPECTED TO TRACK TOWARDS THE WEST-NORTHWEST UNDER THE
INFLUENCE OF THE SUBTROPICAL RIDGE. THE SYSTEM IS
FORECAST TO WEAKEN SLOWLY THROUGHOUT THE FORECAST PERIOD
AS AN INCREASE IN WIND SHEAR IS EXPECTED. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 301200Z6 IS 13 FEET. REFER TO
WWIO31 PGFW FOR ADDITIONAL SEA HEIGHT INFORMATION.
NEXT WARNINGS AT 310300Z7 (DTG 310153Z3).//
=========================================================================
WTXS32 PGTW 971231 03:00z
1. TROPICAL CYCLONE 09S (SELWYN) WARNING NR 009
   01 ACTIVE TROPICAL CYCLONE IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   310000Z4 --- 16.4S1 100.0E1
     MOVEMENT PAST SIX HOURS - 280 DEGREES AT 07 KTS
     POSITION ACCURATE TO WITHIN 045 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   REPEAT POSIT: 16.4S1 100.0E1
    ---
   FORECASTS:
   12 HRS, VALID AT:
   311200Z7 --- 16.2S9 98.6E3
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   VECTOR TO 24 HR POSIT: 280 DEG/ 07 KTS
    ---
   24 HRS, VALID AT:
   010000Z1 --- 15.9S5 97.1E7
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
310300Z7 POSITION 16.4S1   99.6E4
TROPICAL CYCLONE 09S (SELWYN) HAS MOVED WESTWARD AT 07
KNOTS FOR THE PAST 06 HOURS. THE WARNING POSITION IS
BASED ON 202330Z0 VISIBLE SATELLITE IMAGERY ANALYZED BY
PHIK ANALYSTS AND CONTINUITY FROM A 301611Z2 SCATTEROMETER
PASS WHICH ALSO INDICATED THAT THE MAXIMUM INTENSITY WAS 35
KNOTS. THE CONVECTION WITH THIS SYSTEM HAS DIMINISHED WITH
THE NEAREST CONVECTIVE CELLS LOCATED APPROXIMATELY 65NM FROM
THE SYSTEM CENTER. TROPICAL CYCLONE 09S (SELWYN) SHOULD
CONTINUE WESTWARD FOR THE NEXT 24 HOURS AS IT IS STEERED
PRIMARILY BY LOW LEVEL FLOW FROM HIGH PRESSURE LOCATED SOUTH
OF THE CENTER. THE SYSTEM SHOULD CONTINUE TO WEAKEN SLOWLY
THROUGHOUT THE PERIOD AS AN UPPER LEVEL TROUGH APPROACHES
FROM THE WEST INCREASING THE VERTICAL WIND SHEAR. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 310000Z IS 13 FEET. NEXT WARNINGS
AT 311500Z0 (DTG 311353Z6).//
=========================================================================
WTXS32 PGTW 971231 15:00z
1. TROPICAL CYCLONE 09S (SELWYN) WARNING NR 010
   01 ACTIVE TROPICAL CYCLONE IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   311200Z7 --- 16.3S0 98.4E1
     MOVEMENT PAST SIX HOURS - 270 DEGREES AT 08 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
   REPEAT POSIT: 16.3S0 98.4E1
    ---
   FORECASTS:
   12 HRS, VALID AT:
   010000Z1 --- 16.2S9 96.8E3
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER
WATER
   VECTOR TO 24 HR POSIT: 270 DEG/ 08 KTS
    ---
   24 HRS, VALID AT:
   011200Z4 --- 16.2S9 95.2E6
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER
WATER
    ---
REMARKS:
311500Z0 POSITION 16.3S0 98.0E7
TROPICAL CYCLONE 09S (SELWYN) IS MOVING TOWARDS THE WEST
AT 8 KNOTS. THE WARNING POSITION AND INTENSITY ARE BASED
ON 311130Z9 INFRARED SATELLITE IMAGERY. OVER THE PAST 12
HOURS, ANIMATION SHOWS TC 09S IS EXPERIENCING SIGNIFICANT
WIND SHEAR FROM MOSTLY THE NORTH AND CONVECTION REMAINS
MINIMAL. HOWEVER, DURING THE PAST 3 HOURS CONVECTION HAS
BECOME MORE CENTRALLY LOCATED TOWARDS THE EXPOSED LOW-
LEVEL CIRCULATION AND IS NOW LOCATED APPROXIMATELY 40NM
FROM THE CENTER. TROPICAL CYCLONE 09S (SELWYN) IS
EXPECTED TO TRACK TOWARDS THE WEST THROUGH THE FORECAST
PERIOD AS IT IS STEERED BY LOW-LEVEL EASTERLY FLOW. THE
SYSTEM IS EXPECTED TO WEAKEN SLOWLY AS AN APPROACHING
UPPER-LEVEL TROUGH IS EXPECTED TO PASS THROUGH THE AREA
AND INTRODUCE ADDITIONAL VERTICAL WIND SHEAR ON TC 09S.
MAXIMUM SIGNIFICANT WAVE HEIGHT AT 311200Z7 IS 13 FEET.
REFER TO WWIO31 PGFW FOR ADDITIONAL SEA HEIGHT
INFORMATION. NEXT WARNINGS AT 010300Z4 (DTG 010153Z0).//
=========================================================================
WTXS32 PGTW 980101 03:00z CORRECTED
1. TROPICAL CYCLONE 09S (SELWYN) WARNING NR 011
   01 ACTIVE TROPICAL CYCLONE IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   010000Z1 --- 16.3S0 96.2E7
     MOVEMENT PAST SIX HOURS - 270 DEGREES AT 10 KTS
     POSITION ACCURATE TO WITHIN 060 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER
WATER
   REPEAT POSIT: 16.3S0 96.2E7
    ---
   FORECASTS:
   12 HRS, VALID AT:
   011200Z4 --- 16.7S4 94.2E5
   MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER
WATER
    ---
REMARKS:
010300Z4 POSITION 16.4S1   95.7E1
TROPICAL CYCLONE 09S (SELWYN) HAS DISSIPATED AS A
SIGNIFICANT TROPICAL CYCLONE. THE WARNING INTENSITY IS
BASED ON VISIBLE SATELLITE IMAGERY. THE SYSTEM HAS ONLY
SLIGHT PERIPHERAL CONVECTION AND IS SUBJECT TO HEAVY
NORTHERLY SHEAR. TC 09S (SELWYN) IS EXPECTED TO REMAIN IN
A HIGH WINDSHEAR ENVIRONMENT. MAXIMUM SIGNIFICANT WAVE
HEIGHT AT 98010000Z IS 12 FEET. THIS IS THE FINAL WARNING
ON THIS SYSTEM BY THE JOINT TYPHOON WARNING CENTER
(NAVPACMETOCCEN WEST GU). THE SYSTEM WILL BE CLOSELY
MONITORED FOR SIGNS OF REGENERATION.//

Tropical cyclone tracks developed by Michael Bath using operational warnings and advisories.


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Document: tropical_cyclone_selwyn_jtwc_advisories.htm Updated: 4 September 2016