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Tropical Cyclone OLGA : JTWC Advisories
Season 1999-2000 Summaries (Operational Data): [AU] [SIO] [SPAC] [SH]
---> Tropical Cyclone OLGA Track Map and Data

WTXS21 PGTW 20000315 08:30z
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
190 NM EITHER SIDE OF A LINE FROM 17.1S9 118.5E5 TO 17.1S9
108.8E7 WITHIN THE NEXT 06 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 20 TO 25 KNOTS.
METSAT IMAGERY AND SYNOPTIC DATA AT 150630Z5 INDICATE THAT A
CIRCULATION CENTER IS LOCATED NEAR 17.3S1 117.2E1. THE SYSTEM IS
MOVING WESTWARD AT 07 KNOTS.
2. REMARKS:
ANIMATED MULTI-SPECTRAL IMAGERY DEPICTS INCREASED ORGANIZATION OF
THE CONVECTION OVER THE PAST 6 HOURS. IMAGERY ALSO REVEALED LOW
CLOUD LINES MOVING IN TOWARD THE LOW-LEVEL CIRCULATION CENTER
(LLCC) FROM THE SOUTHEAST. A 150108Z5 SPECIAL SENSOR MICROWAVE
IMAGER (SSM/I) PASS FAILED TO DEFINE THE LLCC BUT DID SHOW DEEP
CONVECTION JUST TO THE EAST OF THE SYNOPTIC/SAT LLCC POSITION.
MAXIMUM SUSTAINED WINDS ARE ESTIMATED AT 20 TO 25 KNOTS. MINIMUM
SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1002 MB. THE POTENTIAL
FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE
NEXT 24 HOURS IS GOOD.
3. THIS ALERT VALID UNTIL 160830Z8.//
=========================================================================
WTXS31 PGTW 20000315 15:00z COR
1. TROPICAL CYCLONE 20S WARNING NR 001
   01 ACTIVE TROPICAL CYCLONE IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   151200Z9 --- NEAR 17.1S9 115.7E4
     MOVEMENT PAST SIX HOURS - 275 DEGREES AT 13 KTS
     POSITION ACCURATE TO WITHIN 060 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT
   REPEAT POSIT: 17.1S9 115.7E4
    ---
   FORECASTS:
   12 HRS, VALID AT:
   160000Z7 --- 16.8S5 113.8E3
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   RADIUS OF 035 KT WINDS - 040 NM SOUTH SEMICIRCLE
                            030 NM ELSEWHERE
   VECTOR TO 24 HR POSIT: 265 DEG/ 08 KTS
    ---
   24 HRS, VALID AT:
   161200Z0 --- 17.0S8 112.1E5
   MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
   RADIUS OF 050 KT WINDS - 020 NM
   RADIUS OF 035 KT WINDS - 070 NM SOUTH SEMICIRCLE
                            060 NM ELSEWHERE
   VECTOR TO 36 HR POSIT: 255 DEG/ 07 KTS
    ---
   36 HRS, VALID AT:
   170000Z8 --- 17.4S2 110.7E9
   MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
   RADIUS OF 050 KT WINDS - 030 NM SOUTH SEMICIRCLE
                            020 NM ELSEWHERE
   RADIUS OF 035 KT WINDS - 080 NM SOUTH SEMICIRCLE
                            060 NM ELSEWHERE
   VECTOR TO 48 HR POSIT: 225 DEG/ 08 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   171200Z1 --- 18.6S5 109.5E5
   MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT
   RADIUS OF 050 KT WINDS - 040 NM SOUTHEAST SEMICIRCLE
                            025 NM ELSEWHERE
   RADIUS OF 035 KT WINDS - 090 NM SOUTHEAST SEMICIRCLE
                            070 NM ELSEWHERE
    ---
REMARKS:
151500Z2 POSITION NEAR 17.0S8 115.2E9.
THE AREA OF CONVECTION WHICH WAS THE SUBJECT OF A TROPICAL CYCLONE
FORMATION ALERT, HAS BECOME BETTER ORGANIZED OVER THE PAST 12 HOURS
AND IS EXPECTED TO INTENSIFY INTO A TROPICAL CYCLONE WITHIN THE NEXT
6 TO 12 HOURS. THE SYSTEM, LOCATED APPROXIMATELY 253 NM NORTHWEST OF
PORT HEDLAND, AUSTRALIA, HAS TRACK WESTWARD AT 13 KNOTS DURING THE
PAST 6 HOURS. THE WARNING POSITION IS BASED ON 151130Z1 INFRARED
SATELLITE IMAGERY. THE WARNING INTENSITY IS BASED ON SATELLITE
INTENSITY ESTIMATES OF 25 KNOTS. LOW/MID-LEVEL ANALYSIS INDICATES TC
20S IS TRACKING WITHIN A MID-LEVEL RIDGE SITUATED OVER WESTERN
AUSTRALIA. THE RIDGE IS FORECAST TO CONTINUE BUILDING WESTWARD OFF
OF THE WEST COAST DURING THE NEXT 36 HOURS. AFTERWARD, AN
APPROACHING MAJOR SHORT WAVE TROUGH WILL BEGIN TO AFFECT THE TRACK
CAUSING A SOUTHWESTWARD SHIFT. TC 20S SHOULD INTENSIFY AT A FASTER
THAN NORMAL RATE THROUGH THE NEXT 12 HOURS AS THE SYSTEM MOVES
BENEATH THE RIDGE AXIS. THEN, THE SYSTEM SHOULD INTENSIFY AT A MORE
CLIMATOLOGICAL RATE. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 151200Z9 IS
12 FEET. THIS WARNING SUPERSEDES AND CANCELS NAVPACMETOCCEN 150821Z
MAR 00 TROPICAL CYCLONE FORMATION ALERT (WTXS21 PGTW 150830 ) NEXT
WARNINGS AT 160300Z0 (DTG 160151Z4) AND 161500Z3 (DTG 161351Z7)
JUSTIFICATION: CORRECTED REMARKS.//
=========================================================================
WTXS31 PGTW 20000316 03:00z
1. TROPICAL CYCLONE 20S WARNING NR 002
   01 ACTIVE TROPICAL CYCLONE IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   160000Z7 --- NEAR 16.4S1 113.8E3
     MOVEMENT PAST SIX HOURS - 280 DEGREES AT 11 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
   REPEAT POSIT: 16.4S1 113.8E3
    ---
   FORECASTS:
   12 HRS, VALID AT:
   161200Z0 --- 16.3S0 111.8E1
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   RADIUS OF 035 KT WINDS - 040 NM SOUTH SEMICIRCLE
                            030 NM ELSEWHERE
   VECTOR TO 24 HR POSIT: 260 DEG/ 08 KTS
    ---
   24 HRS, VALID AT:
   170000Z8 --- 16.6S3 110.1E3
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   RADIUS OF 035 KT WINDS - 070 NM SOUTH SEMICIRCLE
                            060 NM ELSEWHERE
   VECTOR TO 36 HR POSIT: 245 DEG/ 08 KTS
    ---
   36 HRS, VALID AT:
   171200Z1 --- 17.3S1 108.5E4
   MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
   RADIUS OF 050 KT WINDS - 035 NM SOUTH SEMICIRCLE
                            025 NM ELSEWHERE
   RADIUS OF 035 KT WINDS - 090 NM SOUTH SEMICIRCLE
                            075 NM ELSEWHERE
   VECTOR TO 48 HR POSIT: 240 DEG/ 08 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   180000Z9 --- 18.1S0 107.1E9
   MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT
   RADIUS OF 050 KT WINDS - 055 NM SOUTHEAST SEMICIRCLE
                            040 NM ELSEWHERE
   RADIUS OF 035 KT WINDS - 120 NM SOUTHEAST SEMICIRCLE
                            095 NM ELSEWHERE
    ---
REMARKS:
160300Z0 POSITION NEAR 16.4S1  113.3E8.
TROPICAL (TC) CYCLONE 20S HAS CONTINUED TO ORGANIZE OVER THE PAST 12
HOURS APPROXIMATELY 330 NM NORTH OF LEARMONTH, AUSTRALIA, AND HAS
TRACK TOWARDS THE WEST AT 11 KNOTS DURING THE PAST 6 HOURS. THE
WARNING POSITION IS BASED ON 152330Z4 INFRARED AND VISIBLE SATELLITE
IMAGERY. THE WARNING INTENSITY IS BASED ON SATELLITE INTENSITY
ESTIMATES OF 30 KNOTS. LOW/MID-LEVEL ANALYSIS INDICATES TC 20S IS
TRACKING WITHIN THE SUBTROPICAL RIDGE SITUATED OVER WESTERN
AUSTRALIA. THE RIDGE IS FORECAST TO CONTINUE BUILDING WEST OFF
AUSTRALIA AND CAUSE TC 20S TO REMAIN ON A RELATIVELY WESTWARD TRACK
DURING THE NEXT 24 HOURS. AFTERWARDS, AN APPROACHING SHORT WAVE
TROUGH IS FORECAST TO CAUSE A MORE SOUTHWESTWARD SHIFT SYSTEM=S
TRACK. UPPER LEVEL ANALYSIS AND UW-CIMSS SHEAR CHARTS INDICATE WEAK
VERTICAL WIND SHEAR ACROSS THE REGION AND GOOD OUTFLOW ALOFT. TC 20S
IS FORECAST TO INTENSIFY AT A NEAR CLIMATOLOGICAL RATE THROUGHOUT
THE FORECAST PERIOD. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 160000Z7 IS
12 FEET. NEXT WARNINGS AT 161500Z3 (DTG 161351Z7) AND 170300Z1 (DTG
170151Z5).//
=========================================================================
WTXS31 PGTW 20000316 15:00z
1. TROPICAL CYCLONE 20S WARNING NR 003 RELOCATED
   01 ACTIVE TROPICAL CYCLONE IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   161200Z0 --- NEAR 16.3S0 113.5E0
     MOVEMENT PAST SIX HOURS - 270 DEGREES AT 05 KTS
     POSITION ACCURATE TO WITHIN 090 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   REPEAT POSIT: 16.3S0 113.5E0
    ---
   FORECASTS:
   12 HRS, VALID AT:
   170000Z8 --- 16.3S0 112.5E9
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   VECTOR TO 24 HR POSIT: 270 DEG/ 07 KTS
    ---
   24 HRS, VALID AT:
   171200Z1 --- 16.3S0 111.0E3
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   VECTOR TO 36 HR POSIT: 260 DEG/ 07 KTS
    ---
   36 HRS, VALID AT:
   180000Z9 --- 16.5S2 109.6E6
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   RADIUS OF 035 KT WINDS - 070 NM SOUTH SEMICIRCLE
                            040 NM ELSEWHERE
   VECTOR TO 48 HR POSIT: 245 DEG/ 09 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   181200Z2 --- 17.2S0 107.9E7
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   RADIUS OF 035 KT WINDS - 080 NM SOUTH SEMICIRCLE
                            050 NM ELSEWHERE
    ---
REMARKS:
161500Z3 POSITION NEAR 16.3S0 113.2E7.
RECENT VISIBLE SATELLITE IMAGERY REVEALS TROPICAL CYCLONE 20S
IS FURTHER TO THE EAST THAN PREVIOUSLY FORECAST. BASED ON VISIBLE
IMAGERY, THE POSITION HAS BEEN RELOCATED 100 NM TO THE EAST OF THE
OF THE PREVIOUS 12 HOUR FORECAST POSITION. TROPICAL (TC) CYCLONE 20S
IS LOCATED APPROXIMATELY 330 NM NORTH OF LEARMONTH, AUSTRALIA, AND
HAS TRACKED WESTWARD AT 05 KNOTS DURING THE PAST 6 HOURS. THE
WARNING POSITION IS BASED ON 161130Z2 INFRARED SATELLITE IMAGERY.
THE WARNING INTENSITY IS BASED ON SATELLITE INTENSITY ESTIMATES OF
30 KNOTS. ANIMATED VISIBLE SATELLITE IMAGERY INDICATED MULTIPLE LOW
LEVEL CIRCULATION CENTERS IN THE VICINITY OF THE CONVECTION. ALSO
EVIDENT WAS A BROAD SCALE CIRCULATION WITH THE CONVECTION SHEARED TO
THE WEST. CURRENT INFRARED IMAGERY INDICATES MUCH OF THE CONVECTION
ALSO BEING SHEARED TO THE SOUTH OF THE MULTIPLE LLCC=S AND BEING
PICKED UP BY AN UPPER-LEVEL TROUGH SOUTH OF THE SYSTEM. A 161042Z4
SSMI PASS ALSO SUPPORTS A MULTITUDE OF POSSIBLE LLCC=S AND A MASS OF
CONVECTION SHEARED TO THE WEST OF THE AREA. UW-CIMSS VERTICAL WIND
SHEAR PRODUCT SHOWS A VERY TIGHT GRADIENT OF INCREASING VERTICAL
WIND SHEAR TO THE SOUTH OF THE SYSTEM. UPPER-LEVEL ANALYSIS ALSO
INDICATES AN UPPER-LEVEL ANTI-CYCLONE TO THE EAST OF THE SYSTEM,
COMBINING WITH THE UPPER-LEVEL TROUGH, TO ENHANCE THE UPPER-LEVEL
WINDS. VERTICAL WIND SHEAR WILL CONTINUE TO INHIBIT DEVELOPMENT OF
THIS SYSTEM AS IT TRACKS TO THE WEST UNDER THE STEERING INFLUENCE OF
THE SUBTROPICAL RIDGE TO THE SOUTH. A MORE FAVORABLE ENVIRONMENT IS
EXPECTED TOWARD THE END OF THE FORECAST WHERE DEVELOPMENT SHOULD
RESUME A CLIMATOLOGICAL RATE. MAXIMUM SIGNIFICANT WAVE HEIGHT AT
161200Z0 IS 12 FEET. NEXT WARNINGS AT 170300Z1 (DTG 170151Z5) AND
171500Z4 (DTG 171351Z8).//
=========================================================================
WTXS31 PGTW 20000317 03:00z
1. TROPICAL CYCLONE 20S WARNING NR 004 RELOCATED
   01 ACTIVE TROPICAL CYCLONE IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   170000Z8 --- NEAR 17.6S4 113.7E2
     MOVEMENT PAST SIX HOURS - 225 DEGREES AT 04 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
   REPEAT POSIT: 17.6S4 113.7E2
    ---
   FORECASTS:
   12 HRS, VALID AT:
   171200Z1 --- 18.2S1 112.6E0
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   VECTOR TO 24 HR POSIT: 245 DEG/ 08 KTS
    ---
   24 HRS, VALID AT:
   180000Z9 --- 18.9S8 111.1E4
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   VECTOR TO 36 HR POSIT: 250 DEG/ 08 KTS
    ---
   36 HRS, VALID AT:
   181200Z2 --- 19.4S4 109.4E4
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   RADIUS OF 035 KT WINDS - 065 NM SOUTH SEMICIRCLE
                            040 NM ELSEWHERE
   VECTOR TO 48 HR POSIT: 245 DEG/ 08 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   190000Z0 --- 20.0S2 107.9E7
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   RADIUS OF 035 KT WINDS - 075 NM SOUTH SEMICIRCLE
                            050 NM ELSEWHERE
    ---
REMARKS:
170300Z1 POSITION NEAR 17.8S6 113.4E9.
RECENT VISIBLE SATELLITE IMAGERY REVEALS TROPICAL CYCLONE (TC) 20S
IS FURTHER TO THE SOUTHEAST THAN PREVIOUSLY FORECAST. BASED ON
ANIMATED VISIBLE SATELLITE IMAGERY, THE POSITION HAS BEEN RELOCATED
APPROXIMATELY 105 NM TO THE SOUTHEAST OF THE PREVIOUS 12 HOUR
FORECAST POSITION. TC 20S IS LOCATED APPROXIMATELY 275 NM NORTH OF
LEARMONTH, AUSTRALIA, AND HAS TRACKED SOUTHWESTWARD AT 04 KNOTS
DURING THE PAST 6 HOURS. THE WARNING POSITION IS BASED ON 162330Z5
VISIBLE AND INFRARED SATELLITE IMAGERY. THE WARNING INTENSITY IS
BASED ON CURRENT SATELLITE INTENSITY ESTIMATES OF 30 KNOTS. ANIMATED
VISIBLE SATELLITE IMAGERY INDICATES A PARTIALLY EXPOSED LOW LEVEL
CIRCULATION CENTER (LLCC) EAST OF THE CONVECTION. UW-CIMSS ANALYSIS
SHOWS A VERY TIGHT GRADIENT OF INCREASING VERTICAL WIND SHEAR TO THE
SOUTH OF THE SYSTEM. UPPER-LEVEL ANALYSIS ALSO INDICATES AN UPPER-
LEVEL ANTI-CYCLONE TO THE EAST OF THE SYSTEM AND A UPPER-LEVEL
TROUGH TO THE SOUTH THAT IS ENHANCING THE UPPER-LEVEL WINDS.
VERTICAL WIND SHEAR WILL SERVE TO INHIBIT DEVELOPMENT OF TC 20S AS
IT TRACKS TO THE WEST-SOUTHWEST UNDER THE STEERING INFLUENCE OF THE
SUBTROPICAL RIDGE TO THE SOUTH. A MORE FAVORABLE UPPER-LEVEL
ENVIRONMENT IS EXPECTED TOWARD THE END OF THE FORECAST PERIOD
ALLOWING THE SYSTEM TO DEVELOP AT A CLIMATOLOGICAL RATE. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 170000Z8 IS 12 FEET. NEXT WARNINGS AT
171500Z4 (DTG 171351Z8) AND 180300Z2 (DTG 180151Z6).//
=========================================================================
WTXS31 PGTW 20000317 15:00z
1. TROPICAL CYCLONE 20S (OLGA) WARNING NR 005
   01 ACTIVE TROPICAL CYCLONE IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   171200Z1 --- NEAR 17.3S1 111.5E8
     MOVEMENT PAST SIX HOURS - 260 DEGREES AT 10 KTS
     POSITION ACCURATE TO WITHIN 090 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   REPEAT POSIT: 17.3S1 111.5E8
    ---
   FORECASTS:
   12 HRS, VALID AT:
   180000Z9 --- 18.1S0 109.9E9
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   VECTOR TO 24 HR POSIT: 240 DEG/ 08 KTS
    ---
   24 HRS, VALID AT:
   181200Z2 --- 18.9S8 108.5E4
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   RADIUS OF 035 KT WINDS - 060 NM SOUTH SEMICIRCLE
                            040 NM ELSEWHERE
   VECTOR TO 36 HR POSIT: 245 DEG/ 06 KTS
    ---
   36 HRS, VALID AT:
   190000Z0 --- 19.4S4 107.3E1
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   RADIUS OF 035 KT WINDS - 080 NM SOUTH SEMICIRCLE
                            050 NM ELSEWHERE
   VECTOR TO 48 HR POSIT: 260 DEG/ 07 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   191200Z3 --- 19.6S6 105.8E4
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   RADIUS OF 035 KT WINDS - 090 NM SOUTH SEMICIRCLE
                            060 NM ELSEWHERE
    ---
REMARKS:
171500Z4 POSITION NEAR 17.5S3 111.1E4.
TC 20S IS LOCATED APPROXIMATELY 335 NM NORTH-NORTHWEST OF LEARMONTH,
AUSTRALIA, AND HAS TRACKED WESTWARD AT 10 KNOTS DURING THE PAST 6
HOURS. THE WARNING POSITION IS BASED ON 171130Z3 INFRARED AND
MICROWAVE SATELLITE IMAGERY. THE WARNING INTENSITY IS BASED ON
CURRENT SATELLITE INTENSITY ESTIMATES OF 30 KNOTS. ANIMATED
SATELLITE IMAGERY AND A 171032Z4 SSMI PASS INDICATE A FULLY EXPOSED,
BROAD, LOW LEVEL CIRCULATION CENTER (LLCC) WITH THE CONVECTION
SHEARED TO THE WEST. UW-CIMSS VERTICAL WIND SHEAR AND SATELLITE
WINDS PRODUCTS CONTINUE TO SHOW A VERY STRONG GRADIENT OF INCREASING
VERTICAL WIND SHEAR TO THE SOUTH OF THE SYSTEM. UPPER-LEVEL ANALYSIS
ALSO INDICATES AN UPPER-LEVEL ANTI-CYCLONE TO THE EAST OF THE
SYSTEM, WHICH COUPLED WITH THE SURFACE RIDGE TO THE SOUTHWEST, IS
MAKING FOR DIRECTIONAL VERTICAL WIND SHEAR OVER THE SYSTEM. ALTHOUGH
THE MID-LEVEL RIDGE IS FORECAST TO WEAKEN WITH THE APPROACH OF A
MID-LATITUDE CYCLONE, THE SURFACE RIDGE IS FORECAST TO BUILD IN
BEHIND THE SYSTEM THAT HAS PASSED, MAINTAINING STEERING FLOW AT
LOWER LEVELS FOR THE LLCC. VERTICAL WIND SHEAR WILL SERVE TO INHIBIT
DEVELOPMENT OF TC 20S AS IT TRACKS TO THE WEST-SOUTHWEST UNDER THE
STEERING INFLUENCE OF THE SUBTROPICAL RIDGE TO THE SOUTH. A MORE
FAVORABLE UPPER-LEVEL ENVIRONMENT IS EXPECTED TOWARD THE END OF THE
FORECAST PERIOD ALLOWING THE SYSTEM TO DEVELOP AT A MORE
CLIMATOLOGICAL RATE. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 171200Z1 IS
14 FEET. NEXT WARNINGS AT 180300Z2 (DTG 180151Z6) AND 181500Z5 (DTG
181351Z9).//
=========================================================================
WTXS31 PGTW 20000318 03:00z
SUBJ:  TROPICAL CYCLONE WARNING
1. TROPICAL CYCLONE 20S (OLGA) WARNING NR 006
   01 ACTIVE TROPICAL CYCLONE IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   180000Z9 --- NEAR 18.3S2 110.0E2
     MOVEMENT PAST SIX HOURS - 235 DEGREES AT 09 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 SOUTHEAST SEMICIRCLE
                            035 NM ELSEWHERE
   REPEAT POSIT: 18.3S2 110.0E2
    ---
   FORECASTS:
   12 HRS, VALID AT:
   181200Z2 --- 19.4S4 108.6E5
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   RADIUS OF 035 KT WINDS - 060 NM SOUTHEAST SEMICIRCLE
                            045 NM ELSEWHERE
   VECTOR TO 24 HR POSIT: 225 DEG/ 09 KTS
    ---
   24 HRS, VALID AT:
   190000Z0 --- 20.6S8 107.3E1
   MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
   RADIUS OF 050 KT WINDS - 020 NM
   RADIUS OF 035 KT WINDS - 070 NM SOUTHEAST SEMICIRCLE
                            055 NM ELSEWHERE
   VECTOR TO 36 HR POSIT: 220 DEG/ 07 KTS
    ---
   36 HRS, VALID AT:
   191200Z3 --- 21.7S0 106.3E0
   MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
   RADIUS OF 050 KT WINDS - 020 NM
   RADIUS OF 035 KT WINDS - 070 NM SOUTHEAST SEMICIRCLE
                            055 NM ELSEWHERE
   VECTOR TO 48 HR POSIT: 220 DEG/ 06 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   200000Z2 --- 22.6S0 105.5E1
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   RADIUS OF 035 KT WINDS - 060 NM SOUTHEAST SEMICIRCLE
                            045 NM ELSEWHERE
    ---
REMARKS:
180300Z2 POSITION NEAR 18.6S5 109.6E6.
TC 20S (OLGA) IS LOCATED APPROXIMATELY 330 NM NORTHWEST OF
LEARMONTH, AUSTRALIA, AND HAS TRACKED SOUTHWESTWARD AT 09 KNOTS
DURING THE PAST 6 HOURS. THE WARNING POSITION IS BASED ON 172330Z6
VISIBLE AND INFRARED SATELLITE IMAGERY. THE WARNING INTENSITY IS
BASED ON CURRENT SATELLITE INTENSITY ESTIMATES OF 35 AND 45 KNOTS.
ANIMATED SATELLITE IMAGERY SHOWS THAT THE TC 20S (OLGA) HAS
INTENSIFIED SLIGHTLY OVER THE PAST 10 HOURS WITH THE LOW-LEVEL
CIRCULATION CENTER (LLCC) LOCATED ON THE EASTERN EDGE OF THE DEEP
CONVECTION. IMAGERY ALSO DEPICTS IMPROVING OUTFLOW OVER TC 20S
(OLGA) EXCEPT IN THE EASTERN QUADRANT, WHICH IS BEING INHIBITED BY
WEAK TO MODERATE EASTERLY FLOW. UW-CIMSS VERTICAL WIND SHEAR
ANALYSIS INDICATES THAT TC 20S (OLGA) HAS CONTINUED TO TRACK INTO A
MORE FAVORABLE ENVIRONMENT BENEATH THE UPPER-LEVEL SUBTROPICAL RIDGE
AXIS. UPPER-LEVEL ANALYSIS ALSO INDICATES AN UPPER-LEVEL ANTICYCLONE
EAST OF THE SYSTEM, WHICH IS PROVIDING THE WEAK EASTERLY FLOW ACROSS
THE SYSTEM. TC 20S (OLGA) IS FORECAST TO TRACK SOUTHWESTWARD TOWARD
THE WEAKNESS IN THE SUBTROPICAL RIDGE, UNDER THE STEERING INFLUENCE
OF THE LOW TO MID-LEVEL RIDGE TO THE SOUTHEAST SITUATED OVER WESTERN
AUSTRALIA. TC 20S IS FORECAST TO INTENSIFY SLOWLY THROUGH THE 24
HOUR FORECAST, THEN TO WEAKEN AS IT ENCOUNTERS INCREASING VERTICAL
WIND SHEAR ASSOCIATED WITH A MID-LATITUDE TROUGH. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 180000Z9 IS 14 FEET. NEXT WARNINGS AT
181500Z5 (DTG 181351Z9) AND 190300Z3 (DTG 190151Z7).//
=========================================================================
WTXS31 PGTW 20000318 15:00z
1. TROPICAL CYCLONE 20S (OLGA) WARNING NR 007
   01 ACTIVE TROPICAL CYCLONE IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   181200Z2 --- NEAR 19.6S6 108.4E3
     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 - 045 KT, GUSTS 055 KT
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   RADIUS OF 035 KT WINDS - 050 NM SOUTHEAST SEMICIRCLE
                            035 NM ELSEWHERE
   REPEAT POSIT: 19.6S6 108.4E3
    ---
   FORECASTS:
   12 HRS, VALID AT:
   190000Z0 --- 20.9S1 107.1E9
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   RADIUS OF 035 KT WINDS - 045 NM SOUTHEAST SEMICIRCLE
                            030 NM ELSEWHERE
   VECTOR TO 24 HR POSIT: 225 DEG/ 07 KTS
    ---
   24 HRS, VALID AT:
   191200Z3 --- 21.9S2 106.0E7
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   VECTOR TO 36 HR POSIT: 240 DEG/ 07 KTS
    ---
   36 HRS, VALID AT:
   200000Z2 --- 22.6S0 104.8E3
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
181500Z5 POSITION NEAR 19.9S9 108.1E0.
TC 20S (OLGA) IS LOCATED APPROXIMATELY 358 NM NORTHWEST OF
LEARMONTH, AUSTRALIA, AND HAS TRACKED SOUTHWESTWARD AT 08 KNOTS
DURING THE PAST 6 HOURS. THE WARNING POSITION IS BASED ON 181130Z4
INFRARED SATELLITE IMAGERY. THE WARNING INTENSITY IS BASED ON
CURRENT SATELLITE INTENSITY ESTIMATES OF 45 KNOTS. AN 180904Z2
TROPICAL RAINFALL MEASURING MISSION (TRMM) PASS DEPICTED A FULLY
EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH ASSOCIATED
CONVECTION DISPLACED ABOUT 68 NM WEST OF THE CENTER. MODERATE
EASTERLY VERTICAL WIND SHEAR GENERATED BY THE UPPER-LEVEL RIDGE
SITUATED SOUTH OF TC 20S CONTINUES TO INHIBIT DEVELOPMENT. TC
20S (OLGA) IS FORECAST TO TRACK SOUTHWESTWARD WITHIN A WEAKNESS IN
THE SUBTROPICAL RIDGE CREATED BY A MAJOR SHORT WAVE TROUGH
SUPPORTING A FRONTAL SYSTEM MOVING TOWARD THE SOUTHWEST COAST OF
AUSTRALIA. TC 20S IS FORECAST TO CONTINUE WEAKENING THROUGH THE
PERIOD. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 181200Z2 IS 14 FEET. NEXT
WARNINGS AT 190300Z3 (DTG 190151Z7) AND 191500Z6 (DTG 191351Z0).//
=========================================================================
WTXS31 PGTW 20000319 03:00z
SUBJ:  TROPICAL CYCLONE WARNING
1. TROPICAL CYCLONE 20S (OLGA) WARNING NR 008
   01 ACTIVE TROPICAL CYCLONE IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   190000Z0 --- NEAR 21.1S4 105.8E4
     MOVEMENT PAST SIX HOURS - 245 DEGREES AT 14 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
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   REPEAT POSIT: 21.1S4 105.8E4
    ---
   FORECASTS:
   12 HRS, VALID AT:
   191200Z3 --- 22.3S7 103.5E9
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   VECTOR TO 24 HR POSIT: 240 DEG/ 11 KTS
    ---
   24 HRS, VALID AT:
   200000Z2 --- 23.4S9 101.5E7
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   VECTOR TO 36 HR POSIT: 255 DEG/ 11 KTS
    ---
   36 HRS, VALID AT:
   201200Z5 --- 24.0S6 99.3E1
   MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
190300Z3 POSITION NEAR 21.4S7 105.2E8.
TC 20S (OLGA) IS LOCATED APPROXIMATELY 465 NM WEST OF LEARMONTH,
AUSTRALIA, AND HAS TRACKED WEST-SOUTHWESTWARD AT 14 KNOTS DURING THE
PAST 6 HOURS. THE WARNING POSITION IS BASED ON 182330Z7 VISIBLE AND
INFRARED SATELLITE IMAGERY. THE WARNING INTENSITY IS BASED ON
CURRENT SATELLITE INTENSITY ESTIMATES OF 30 AND 35 KNOTS. ANIMATED
INFRARED AND VISIBLE SATELLITE IMAGERY DEPICT A PARTIALLY-EXPOSED
LOW-LEVEL CIRCULATION CENTER (LLCC) SHEARED ABOUT 50 NM EAST OF THE
DEEP CONVECTION. IMAGERY ALSO SHOWS THAT CONVECTION HAS REMAINED
ISOLATED, BUT HAS INTENSIFIED SLIGHTLY OVER THE PAST 6 HOURS. AN
182312Z7 SPECIAL SENSOR MICROWAVE IMAGER PASS ALSO SHOWS THAT DEEP
CONVECTION HAS INCREASED IN AREAL EXTENT OVER THE PAST 10 HOURS.
BOTH THE 200 MB ANALYSIS AND THE UW-CIMSS SHEAR ANALYSIS INDICATE
THAT TC 20S (OLGA) HAS REMAINED JUST NORTH OF THE SUBTROPICAL RIDGE
AXIS UNDER MODERATE EAST-NORTHEASTERLY FLOW, WHICH CONTINUES TO
INHIBIT DEVELOPMENT. TC 20S (OLGA) IS FORECAST TO TRACK WEST-
SOUTHWESTWARD TOWARD A WEAKNESS IN THE SUBTROPICAL RIDGE CREATED BY
A MAJOR SHORT WAVE TROUGH SUPPORTING A FRONTAL SYSTEM MOVING TOWARD
THE SOUTHWEST COAST OF AUSTRALIA. TC 20S IS FORECAST TO CONTINUE
WEAKENING THROUGH THE PERIOD AS IT TRACKS INTO INCREASING VERTICAL
WIND SHEAR. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 190000Z0 IS 14 FEET.
NEXT WARNINGS AT 191500Z6 (DTG 191351Z0) AND 200300Z5 (DTG
200151Z9).//
=========================================================================
WTXS31 PGTW 20000319 09:00z AMD
1. TROPICAL CYCLONE 20S (OLGA) WARNING NR 008A AMENDED
   01 ACTIVE TROPICAL CYCLONE IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   190600Z6 --- NEAR 22.0S4 105.2E8
     MOVEMENT PAST SIX HOURS - 220 DEGREES AT 10 KTS
     POSITION ACCURATE TO WITHIN 040 NM
     POSITION BASED ON CENTER LOCATED BY A COMBINATION OF
     SATELLITE AND SYNOPTIC DATA
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   REPEAT POSIT: 22.0S4 105.2E8
    ---
   FORECASTS:
   12 HRS, VALID AT:
   191800Z9 --- 23.4S9 103.1E5
   MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
190900Z9 POSITION NEAR 22.3S7 104.7E2.
TC 20S (OLGA) IS LOCATED APPROXIMATELY 494 NM WEST OF LEARMONTH,
AUSTRALIA, AND HAS TRACKED SOUTHWESTWARD AT 10 KNOTS DURING THE
PAST 6 HOURS. THE WARNING POSITION IS BASED ON 190530Z8 VISIBLE
SATELLITE IMAGERY. THE WARNING INTENSITY IS BASED ON CURRENT
SATELLITE INTENSITY ESTIMATES AND SYNOPTIC DATA OF 30 KNOTS.
ANIMATED VISIBLE IMAGERY CONTINUES TO DEPICT A FULLY EXPOSED LOW-
LEVEL CIRCULATION CENTER (LLCC). THE CONVECTION ASSOCIATED WITH THE
SYSTEM HAS BEEN DISPLACED 70 TO 100 NM WEST OF THE CENTER FOR OVER
24 HOURS. IMAGERY ALSO SHOWS A STRATOCUMULUS DECK REPLACING THE
ISOLATED CONVECTION OVER THE SOUTHERN PERIPHERY. JUSTIFICATION FOR
AMENDMENT: FINAL WARNING ON TC 20S BASED ON CURRENT INTENSITY. THIS
IS THE FINAL WARNING ON THIS SYSTEM BY THE JOINT TYPHOON WARNING
CENTER (NAVPACMETOCCEN). 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_olga_jtwc_advisories.htm Updated: 4 September 2016