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Tropical Cyclone 199901 : JTWC Advisories
Season 1998-1999 Summaries (Operational Data): [AU] [SIO] [SPAC] [SH]
---> Tropical Cyclone 199901 Track Map and Data

WTXS31 PGTW 980723 09:00z
1. TROPICAL CYCLONE 01S WARNING NR 001
   01 ACTIVE TROPICAL CYCLONE IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   230600Z1 --- 10.5S6 76.4E7
     MOVEMENT PAST SIX HOURS - 260 DEGREES AT 07 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: 10.5S6 76.4E7
    ---
   FORECASTS:
   12 HRS, VALID AT:
   231800Z4 --- 10.7S8 75.0E2
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   VECTOR TO 24 HR POSIT: 260 DEG/ 07 KTS
    ---
   24 HRS, VALID AT:
   240600Z2 --- 11.0S2 73.6E6
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   RADIUS OF 035 KT WINDS - 060 NM SOUTH SEMICIRCLE
                            050 NM ELSEWHERE
   VECTOR TO 36 HR POSIT: 260 DEG/ 07 KTS
    ---
   36 HRS, VALID AT:
   241800Z5 --- 11.2S4 72.2E1
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   RADIUS OF 035 KT WINDS - 060 NM SOUTH SEMICIRCLE
                            050 NM ELSEWHERE
   VECTOR TO 48 HR POSIT: 260 DEG/ 06 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   250600Z3 --- 11.4S6 70.9E6
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   RADIUS OF 035 KT WINDS - 060 NM SOUTH SEMICIRCLE
                            050 NM ELSEWHERE
   VECTOR TO 72 HR POSIT: 255 DEG/ 07 KTS
    ---
   72 HRS, VALID AT:
   260600Z4 --- 12.1S4 68.0E4
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   RADIUS OF 035 KT WINDS - 060 NM SOUTH SEMICIRCLE
                            050 NM ELSEWHERE
    ---
REMARKS:
230900Z4 POSITION 10.5S6 76.0E3. TROPICAL DEPRESSION 01S IS MOVING
WEST AT 7 KNOTS. ANIMATED WATER VAPOR IMAGERY SHOWS THE MODERATE
VERTICAL WIND SHEAR, WHICH HAS BEEN RETARDING THE SYSTEM=S
INTENSIFICATION, HAS ABATED OVER THE PAST 12 HOURS. THE CURRENT
WARNING POSITION IS BASED UPON VISIBLE SATELLITE IMAGERY AND THE
INTENSITY IS BASED UPON SATELLITE INTERPRETATION OF A DVORAK CURRENT
INTENSITY OF 2.0 (30 KNOTS). THE WIND RADII ARE A COMBINATION OF
CLIMATOLOGY AND SATELLITE INTERPRETATION. THE FORECAST TRACK IS IN
AGREEMENT WITH THE TROPICAL FORECAST AIDS AS THE SYSTEM TRAVELS NORTH
OF THE SUBTROPICAL RIDGE. SINCE NOGAPS ANALYSIS SHOWS THE TROPICAL
DEPRESSION MAY COME UNDER ADDITIONAL SHEAR WITHIN THE NEXT 36 HOURS,
WHICH WOULD RETARD FURTHER INTENSIFICATION, THE SYSTEM IS FORECAST TO
INTENSIFY JUST SLIGHTLY WITHIN THE NEXT 72 HOURS. MAXIMUM SIGNIFICANT
WAVE HEIGHT AT 230600Z1 IS 12 FEET. REFER TO WWIO30 PGFW FOR
ADDITIONAL SEA HEIGHT INFORMATION. THIS WARNING SUPERSEDES AND CANCELS
NAVPACMETOCCEN WEST GU 230451Z5 JUL 98 TROPICAL CYCLONE FORMATION
ALERT (WTXS21 PGTW 230500Z0) NEXT WARNINGS AT 231500Z1 (DTG 231351Z5),
232100Z8 (DTG 231951Z1), 240300Z9 (DTG 240151Z3) AND 240900Z5 (DTG
240751Z9).//
=========================================================================
WTXS31 PGTW 980723 15:00z
1. TROPICAL CYCLONE 01S WARNING NR 002
   01 ACTIVE TROPICAL CYCLONE IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   231200Z8 --- 9.9S8 75.8E0
     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 - 030 KT, GUSTS 040 KT
   REPEAT POSIT: 9.9S8 75.8E0
    ---
   FORECASTS:
   12 HRS, VALID AT:
   240000Z6 --- 9.8S7 74.4E5
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   VECTOR TO 24 HR POSIT: 275 DEG/ 07 KTS
    ---
   24 HRS, VALID AT:
   241200Z9 --- 9.7S6 72.9E8
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   VECTOR TO 36 HR POSIT: 275 DEG/ 07 KTS
    ---
   36 HRS, VALID AT:
   250000Z7 --- 9.6S5 71.4E2
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   VECTOR TO 48 HR POSIT: 270 DEG/ 07 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   251200Z0 --- 9.6S5 70.0E7
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   VECTOR TO 72 HR POSIT: 275 DEG/ 07 KTS
    ---
   72 HRS, VALID AT:
   261200Z1 --- 9.4S3 67.1E4
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
    ---
REMARKS:
231500Z1 POSITION  9.9S8   75.4E6.
TROPICAL CYCLONE 01S IS MOVING WESTWARD AT 06 KNOTS. MOST RECENT
VISIBLE SATELLITE IMAGERY AS WELL AS ANIMATED INFRARED SATELLITE
IMAGERY INDICATE THAT UPPER-LEVEL WIND SHEAR HAS INCREASED,
COMPLETELY EXPOSING THE LOWER LEVEL CIRCULATION. HOWEVER, THE
LOWER-LEVEL APPEARS TO BE BETTER ORGANIZED THAN BEFORE AND MORE
INDICATIVE OF STRONG SURFACE WINDS. THE SYSTEM IS THEREFORE
FORECAST TO REACH MINIMAL TROPICAL STORM STRENGTH BEFORE LOSING
LOW-LEVEL ORGANIZATION TO THE CONTINUED UPPER-LEVEL SHEAR. TC 01S
IS EXPECTED TO REMAIN EQUATORWARD, WITH SHALLOW STEERING
INFLUENCE, OF THE SUBTROPICAL RIDGE THROUGHOUT THE FORECAST
PERIOD. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 231200Z IS 12 FEET.
NEXT WARNINGS AT 232100Z8 (DTG 231951Z1), 240300Z9 (DTG
240151Z3), 240900Z5 (DTG 240751Z9) AND 241500Z2 (DTG 241351Z6).
=========================================================================
WTXS31 PGTW 980723 21:00z
1. TROPICAL CYCLONE 01S WARNING NR 003
   01 ACTIVE TROPICAL CYCLONE IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   231800Z4 --- 9.6S5 076.2E5
     MOVEMENT PAST SIX HOURS - 335 DEGREES AT 02 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: 9.6S5 076.2E5
    ---
   FORECASTS:
   12 HRS, VALID AT:
   240600Z2 --- 9.3S2 075.4E6
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   VECTOR TO 24 HR POSIT: 270 DEG/ 06 KTS
    ---
   24 HRS, VALID AT:
   241800Z5 --- 9.3S2 074.2E3
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   VECTOR TO 36 HR POSIT: 270 DEG/ 06 KTS
    ---
   36 HRS, VALID AT:
   250600Z3 --- 9.3S2 072.9E8
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   VECTOR TO 48 HR POSIT: 265 DEG/ 07 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   251800Z6 --- 9.4S3 71.4E2
   MAX SUSTAINED WINDS - 025 KT, GUSTS 040 KT
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
232100Z8 POSITION  9.5S4   076.0E3.
TROPICAL CYCLONE 01S IS QUASISTATIONARY. THE WARNING POSITION IS
BASED PRIMARILY ON A 231558Z4 MICROWAVE IMAGER (SSM/I) PASS. OVER
THE LAST SIX HOURS, DEEP AND MID-LEVEL CONVECTION HAS SHEARED
OFF. THIS, ALONG WITH A LOSS OF CIRCULATION ORGANIZATION HAS MADE
THE SYSTEM DIFFICULT TO POSITION. HOWEVER, OVER THE LAST TWO
HOURS, SOME MID-LEVEL CONVECTION HAS REAPPEARED NEAR THE CENTER.
TC 01S IS CURRENTLY IN AN AREA OF LIGHT STEERING. WITHIN THE NEXT
12 TO 18 HOURS, THE SYSTEM IS EXPECTED TO BECOME INFLUENCED BY
THE SUBTROPICAL RIDGE LOCATED TO THE SOUTH-SOUTHEAST. UPPERLEVEL
SHEAR IS FORECAST TO RE-INTENSIFY AND REMAIN A FAIRLY CONSTANT
FACTOR THROUGH 48 HOURS. ALTHOUGH THE INTENSITY IS EXPECTED TO BE
BELOW SOUTHERN HEMISPHERE WARNING CRITERIA THROUGH THE LAST 24 TO
36 HOURS, THE FORECAST IS EXTENDED DUE TO PROXIMITY TO DIEGO
GARCIA. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 231800Z4 IS 12 FEET.
NEXT WARNINGS AT 240300Z9 (DTG 240151Z3), 240900Z5 (DTG
240751Z9), 241500Z2 (DTG 241351Z6) AND 242100Z9 (DTG
241951Z2).//
=========================================================================
WTXS31 PGTW 980724 03:00z
1. TROPICAL CYCLONE 01S WARNING NR 004
   01 ACTIVE TROPICAL CYCLONE IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   240000Z6 --- 9.5S4 76.0E3
     MOVEMENT PAST SIX HOURS - 295 DEGREES AT 02 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: 9.5S4 76.0E3
    ---
   FORECASTS:
   12 HRS, VALID AT:
   241200Z9 --- 9.4S3 75.7E9
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   VECTOR TO 24 HR POSIT: 290 DEG/ 03 KTS
    ---
   24 HRS, VALID AT:
   250000Z7 --- 9.2S1 75.1E3
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   VECTOR TO 36 HR POSIT: 270 DEG/ 03 KTS
    ---
   36 HRS, VALID AT:
   251200Z0 --- 9.2S1 74.4E5
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
240300Z9 POSITION  9.5S4 75.9E1.
TROPICAL CYCLONE 01S IS QUASISTATIONARY SOUTHEAST OF DIEGO
GARCIA. THE WARNING POSITION IS BASED ON ANIMATED INFRARED
IMAGERY. ANIMATED INFRARED AS WELL AS ANIMATED WATER VAPOR
IMAGERY SHOW MODERATE VERTICAL WIND SHEAR IS ONCE AGAIN AFFECTING
TOPICAL CYCLONE 01S. ALTHOUGH RECENT IMAGERY SHOWS SOME
CONVECTION OVER THE LOW LEVEL CIRCULATION, NOGAPS ANALYSIS
INDICATES THE SHEAR ENVIRONMENT WILL CONTINUE FOR THE REMAINDER
OF THE FORECAST PERIOD AND THIS CONVECTION SHOULD BE SHEARED
OFF TO THE SOUTHWEST.  DUE TO THE HIGH SHEAR ENVIRONMENT,
IT IS UNLIKELY THAT TC 01S WILL INTENSIFY AS IT MOVES SLOWLY
WESTWARD. ALTHOUGH WE ARE CONTINUING THE WARNING DUE
TO THE SYSTEM=S PROXIMITY TO DIEGO GARCIA, WE ARE SWITCHING TO 12
HOUR UPDATES. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 240000Z6 IS 12
FEET. NEXT WARNING IS AT 241500Z2 (DTG 241351Z6) AND 250300Z0
(DTG 250151Z4).//
=========================================================================
WTXS31 PGTW 980724 15:00z
1. TROPICAL CYCLONE 01S WARNING NR 005
   01 ACTIVE TROPICAL CYCLONE IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   241200Z9 --- 9.2S1 076.1E4
     MOVEMENT PAST SIX HOURS - 360 DEGREES AT 01 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: 9.2S1 076.1E4
    ---
   FORECASTS:
   12 HRS, VALID AT:
   250000Z7 --- 9.0S9 076.0E3
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   VECTOR TO 24 HR POSIT: 280 DEG/ 03 KTS
    ---
   24 HRS, VALID AT:
   251200Z0 --- 8.9S7 075.4E6
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   VECTOR TO 36 HR POSIT: 270 DEG/ 04 KTS
    ---
   36 HRS, VALID AT:
   260000Z8 --- 8.9S7 074.5E6
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
241500Z2 POSITION  9.2S1   076.1E4.
TROPICAL CYCLONE 01S REMAINS QUASI-STATIONARY IN THE SOUTH INDIAN
OCEAN. THE WARNING POSITION IS BASED ON VISIBLE SATELLITE
IMAGARY. ANIMATED INFRARED AND WATER-VAPOR IMAGERY INDICATE THAT
THE SYSTEM CONTINUES TO BE AFFECTED BY UPPER-LEVEL CROSS-
EQUATORIAL SHEAR. CURRENTLY IN AN AREA OF MINIMAL STEERING, THE
SYSTEM IS FORECAST TO BECOME INFLUENCED BY THE RIDGING LOCATED TO
ITS WEST-SOUTHWEST AND BEGIN TO TRACK WESTWARD WITHIN THE NEXT 24
HOURS. TC 01S IS EXPECTED TO REMAIN WITHIN AN ENVIRONMENT OF
SIGNIFICANT VERTICAL SHEAR THROUGHOUT THE FORECAST PERIOD, AND
WEAKEN BELOW TROPICAL DEPRESSION STRENGTH AFTER THE 36 HOUR
POSITION. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 240000Z6 IS 12 FEET.
NEXT WARNINGS AT 250300Z0 (DTG 250151Z4) AND 251500Z3 (DTG
251351Z7).//
=========================================================================
WTXS31 PGTW 250300
1. TROPICAL CYCLONE 01S WARNING NR 006
   01 ACTIVE TROPICAL CYCLONE IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   250000Z7 --- 8.8S6 77.2E6
     MOVEMENT PAST SIX HOURS - 090 DEGREES AT 05 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: 8.8S6 77.2E6
    ---
   FORECASTS:
   12 HRS, VALID AT:
   251200Z0 --- 8.7S5 77.8E2
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
250300Z0 POSITION  8.8S6   77.4E8.
ANIMATED INFRARED SATELLITE IMAGERY INDICATES TROPICAL CYCLONE
01S HAS ENTERED AN AREA WITH INCREASED VERTICAL WIND SHEAR. 242330Z4
INFRARED SATELLITE IMAGERY INDICATES MINIMAL CONVECTION REMAINS NEAR
THE CENTER. THEREFOR, THIS SYSTEM HAS DISSIPATED AS A SIGNIFICANT
TROPICAL CYCLONE. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 250000Z7 IS
12 FEET. REFER TO WWIO30 PGFW FOR ADDITIONAL SEA HEIGHT INFORMATION.
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_199901_jtwc_advisories.htm Updated: 4 September 2016