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Tropical Cyclone 200421 : JTWC Advisories
Season 2003-2004 Summaries (Operational Data): [AU] [SIO] [SPAC] [SH]
---> Tropical Cyclone 200421 Track Map and Data

WTXS33 PGTW 20040323 21:00z RTD
MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE WARNING//
RMKS/
IMMEDIATE DELIVERY REQ TO AMEMBASSY PORT LOUIS
1. TROPICAL CYCLONE 21S WARNING NR 001
   03 ACTIVE TROPICAL CYCLONES IN SOUTHIO
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   231800Z4 --- NEAR 8.5S3 56.0E1
     MOVEMENT PAST SIX HOURS - 090 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: 8.5S3 56.0E1
    ---
   FORECASTS:
   12 HRS, VALID AT:
   240600Z2 --- 8.6S4 56.1E2
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   VECTOR TO 24 HR POSIT: 215 DEG/ 02 KTS
    ---
   24 HRS, VALID AT:
   241800Z5 --- 8.9S7 55.9E9
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   RADIUS OF 034 KT WINDS - 055 NM
   VECTOR TO 36 HR POSIT: 220 DEG/ 04 KTS
    ---
   36 HRS, VALID AT:
   250600Z3 --- 9.5S4 55.4E4
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT
                            040 NM SOUTHEAST QUADRANT
                            030 NM SOUTHWEST QUADRANT
                            030 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 075 NM NORTHEAST QUADRANT
                            090 NM SOUTHEAST QUADRANT
                            075 NM SOUTHWEST QUADRANT
                            075 NM NORTHWEST QUADRANT
   VECTOR TO 48 HR POSIT: 220 DEG/ 04 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   251800Z6 --- 10.1S2 54.9E8
   MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT
   RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT
                            060 NM SOUTHEAST QUADRANT
                            050 NM SOUTHWEST QUADRANT
                            050 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 115 NM NORTHEAST QUADRANT
                            125 NM SOUTHEAST QUADRANT
                            115 NM SOUTHWEST QUADRANT
                            115 NM NORTHWEST QUADRANT
    ---
REMARKS:
232100Z8 POSITION NEAR 8.5S3 56.0E1.
TROPICAL CYCLONE (TC) 21S, IS LOCATED APPROXIMATELY 825 NM
NORTHEAST OF ANTANANARIVO, MADAGASCAR IN THE SOUTH INDIAN OCEAN,
AND HAS BEEN QUASISTATIONARY OVER THE PAST 06 HOURS. THE WARNING
POSITION IS BASED ON 231730Z6 INFRARED SATELLITE IMAGERY. THE
WARNING INTENSITY IS BASED ON SATELLITE CURRENT INTENSITY ESTIMATES
OF 25 KNOTS AND QUIKSCAT WINDS DEPICTING 35 TO 40 KNOTS NORTH OF
THE LOW LEVEL CIRCULATION CENTER. TC 21S IS FORECAST TO CONTINUE TO
REMAIN QUASISTATIONARY IN A WEAK STEERING ENVIRONMENT AND THEN
BEGIN TO TRACK POLEWARD LATER IN THE FORECAST PERIOD AS A LOW TO
MID-LEVEL NEAR EQUATORIAL STEERING RIDGE BUILDS IN FROM THE
NORTHEAST. TC 21S IS EXPECTED TO INTENSIFY SLOWLY THEN INTENSIFY AT
A CLIMATOLOGICAL RATE AFTER 12 TO 24 HOURS AS TWO OF THE THREE
AVAILABLE DYNAMIC MODELS PREDICT VERY FAVORABLE OUTFLOW CONDITIONS
TO OCCUR. THE AVAILABLE DYNAMIC AIDS, CONSISTING OF NOGAPS, NCEP GFS,
WBAR, AND EGRR ARE IN FAIR AGREEMENT WITH THIS SCENARIO. NOGAPS
INITIALIZES ON TC 21S AS A VERY WEAK SYSTEM AND DOES NOT EXPECT IT TO
DEVELOP MUCH DUE TO A FORECASTED ENVIRONMENT OF LINEAR FLOW ALOFT AND
MODERATE VERTICAL SHEAR. THIS FORECAST IS BASED ON A CONSENSUS OF
EGRR, WBAI AND GFS WITH LESS EMPHASIS ON NOGAPS. MAXIMUM SIGNIFICANT
WAVE HEIGHT AT 231800Z4 IS 9 FEET. NEXT WARNINGS AT 240900Z5 AND
242100Z9. REFER TO TROPICAL CYCLONE 18S (FAY) WARNINGS (WTXS31 PGTW)
FOR TWELVE-HOURLY UPDATES. REFER TO TROPICAL CYCLONE 20S WARNINGS
(WTXS32 PGTW) FOR TWELVE-HOURLY UPDATES.//
=========================================================================
WTXS33 PGTW 20040324 09:00z
MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE WARNING//
RMKS/
IMMEDIATE DELIVERY REQ TO AMEMBASSY PORT LOUIS
1. TROPICAL CYCLONE 21S WARNING NR 002
   03 ACTIVE TROPICAL CYCLONES IN SOUTHIO
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   240600Z2 --- NEAR 8.6S4 56.1E2
     MOVEMENT PAST SIX HOURS - 135 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: 8.6S4 56.1E2
    ---
   FORECASTS:
   12 HRS, VALID AT:
   241800Z5 --- 8.8S6 55.9E9
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   VECTOR TO 24 HR POSIT: 225 DEG/ 02 KTS
    ---
   24 HRS, VALID AT:
   250600Z3 --- 9.1S0 55.6E6
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   VECTOR TO 36 HR POSIT: 190 DEG/ 03 KTS
    ---
   36 HRS, VALID AT:
   251800Z6 --- 9.6S5 55.5E5
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   VECTOR TO 48 HR POSIT: 200 DEG/ 03 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   260600Z4 --- 10.1S2 55.3E3
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   RADIUS OF 034 KT WINDS - 065 NM NORTHEAST QUADRANT
                            050 NM SOUTHEAST QUADRANT
                            050 NM SOUTHWEST QUADRANT
                            065 NM NORTHWEST QUADRANT
    ---
REMARKS:
240900Z5 POSITION NEAR 8.6S4 56.1E2.
TROPICAL CYCLONE (TC) 21S, IS LOCATED APPROXIMATELY 835 NM
NORTHEAST OF ANTANANARIVO, MADAGASCAR IN THE SOUTH INDIAN OCEAN,
AND HAS BEEN QUASI-STATIONARY OVER THE PAST 06 HOURS. THE WARNING
POSITION IS BASED ON 240530Z4 MULTI-SPECTRAL SATELLITE IMAGERY. THE
WARNING INTENSITY IS BASED ON SATELLITE CURRENT INTENSITY ESTIMATES
OF 25 KNOTS AND QUIKSCAT WINDS DEPICTING 35 TO 40 KNOTS NORTH OF
THE LOW LEVEL CIRCULATION CENTER (LLCC). RECENT SATELLITE IMAGERY REVEALS
THAT THE LLCC IS VERY DIFFICULT TO LOCATE, THUS THE SYSTEM DOES NOT APPEAR
TO HAVE INTENSIFIED IN THE PAST 12 HOURS. TC 21S SHOULD REMAIN QUASI-
STATIONARY IN A WEAK STEERING ENVIRONMENT THROUGH THE FIRST 12 TO 24
HOURS. THEREAFTER, IT IS FORECAST TO DRIFT SOUTHWARD AS THE LOW TO MID
LEVEL RIDGE TO THE SOUTH WEAKENS, AND THE RIDGE TO THE EAST PROVIDES THE
DOMINANT STEERING FLOW. UPPER LEVEL ANALYSIS REVEALS TC 21S IS LOCATED
UNDERNEATH UPPER LEVEL SOUTHERLIES FROM A RIDGE TO THE WEST, WHICH IS
INHIBITING DEVELOPMENT. SINCE 21S IS SO DISORGANIZED AT THIS POINT, AND
CONDITIONS ARE NOT EXPECTED TO IMPROVE, THE SYSTEM IS EXPECTED TO MAINTAIN
INTENSITY THROUGH THE FIRST 24 HOURS. THEREAFTER, IT SHOULD INTENSIFY AT A
CLIMATOLOGICAL RATE UNDER IMPROVING OUTFLOW CONDITIONS. THE AVAILABLE
DYNAMIC AIDS, CONSISTING OF NOGAPS, NCEP GFS, WBAR, AND EGRR ARE IN FAIR
AGREEMENT WITH THIS SCENARIO. THIS FORECAST IS BASED ON A CONSENSUS OF OF
THE AVAILABLE DYNAMIC AIDS. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 240600Z2 IS
12 FEET. NEXT WARNINGS AT 242100Z9 AND 250900Z6. REFER TO TROPICAL CYCLONE
18S (FAY) WARNINGS (WTXS31 PGTW) FOR TWELVE-HOURLY UPDATES. REFER TO
TROPICAL CYCLONE 20S (OSCAR) WARNINGS (WTXS32 PGTW) FOR TWELVE-HOURLY
UPDATES.//
=========================================================================
WTXS33 PGTW 20040324 15:00z
MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE WARNING//
RMKS/
IMMEDIATE DELIVERY REQ TO AMEMBASSY PORT LOUIS
1. TROPICAL CYCLONE 21S WARNING NR 003
   03 ACTIVE TROPICAL CYCLONES IN SOUTHIO
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   241200Z9 --- NEAR 8.7S5 56.1E2
     MOVEMENT PAST SIX HOURS - 180 DEGREES AT 01 KTS
     POSITION ACCURATE TO WITHIN 060 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 020 KT, GUSTS 030 KT
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   REPEAT POSIT: 8.7S5 56.1E2
    ---
   FORECASTS:
   12 HRS, VALID AT:
   250000Z7 --- 9.0S9 55.8E8
   MAX SUSTAINED WINDS - 020 KT, GUSTS 030 KT
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
241500Z2 POSITION NEAR 8.8S6 56.0E1.
TROPICAL CYCLONE (TC) 21S, IS LOCATED APPROXIMATELY 835 NM NORTHEAST
OF ANTANANARIVO, MADAGASCAR IN THE SOUTH INDIAN OCEAN, AND HAS BEEN
QUASI-STATIONARY OVER THE PAST 06 HOURS. THE WARNING POSITION IS
BASED ON 241130Z1 MULTI-SPECTRAL SATELLITE IMAGERY. THE WARNING
INTENSITY IS BASED ON A RECENT QUIKSCAT PASS. RECENT ANIMATED
SATELLITE IMAGERY REVEALS THAT A SINGLE LOW LEVEL CIRCULATION CENTER
(LLCC) CONTINUES TO BE VERY DIFFICULT TO LOCATE, WHICH IS CONCLUSIVE
EVIDENCE THAT THE SYSTEM HAS YET TO BEGIN TO DEVELOP. UPPER LEVEL
AND SATELLITE ANALYSIS SHOWS THAT THE SYSTEM HAS DISSIPATED DUE TO
HIGH WEST-SOUTHWESTERLY VERTIAL WIND SHEAR AND LACK OF CONVECTIVE
ORGANIZATION. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 241200Z9 IS 12FEET.
THIS IS THE FINAL WARNING ON THIS SYSTEM BY THE JOINT TYPHOON
WARNING CENTER (NAVPACMETOCCEN). THIS AREA IS EXPECTED TO BECOME
MORE FAVORABLE FOR DEVELOPMENT SO THE REMNANTS WILL BE CLOSELY
MONITORED FOR SIGNS OF REGENERATION. REFER TO TROPICAL CYCLONE 18S
(FAY) WARNINGS (WTXS31 PGTW) FOR TWELVE-HOURLY UPDATES. REFER TO
TROPICAL CYCLONE 20S (OSCAR) WARNINGS (WTXS32 PGTW) FOR TWELVE-
HOURLY UPDATES.//

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


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Document: tropical_cyclone_200421_jtwc_advisories.htm Updated: 2 May 2017