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Tropical Cyclone ROBYN : JTWC Advisories
Season 2009-2010 Summaries (Operational Data): [AU] [SIO] [SPAC] [SH]
---> Tropical Cyclone ROBYN Track Map and Data

WTXS21 PGTW 20100402 01:30z
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN 130
NM EITHER SIDE OF A LINE FROM 9.7S 92.8E TO 15.1S 92.4E WITHIN THE
NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY ISSUANCE OF NUM-
BERED TROPICAL CYCLONE WARNINGS AT THIS TIME. WINDS IN THE AREA ARE
ESTIMATED TO BE 30 TO 35 KNOTS. METSAT IMAGERY AT 012330Z INDICATES
THAT A CIRCULATION CENTER IS LOCATED NEAR 10.7S 92.5E. THE SYSTEM IS
MOVING SOUTHWESTWARD AT 13 KNOTS.
2. REMARKS: THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 10.3S
92.8E IS NOW LOCATED NEAR 10.7S 92.5E, APPROXIMATELY 270 NM WEST-
NORTHWEST OF COCOS ISLAND. ANIMATED INFRARED SATELLITE IMAGERY SHOWS
AN AREA OF DEEP CONVECTION HAS CONTINUED TO BUILD TOWARDS A LOW
LEVEL CIRCULATION CENTER (LLCC), SUPPORTED BY A 011933Z AMSU-B PASS.
A RECENT 011505Z ASCAT PASS REVEALED A WELL DEFINED LLCC WITH WINDS
BETWEEN 20 AND 25 KNOTS ALONG THE WESTERN PERIPHERY. SURFACE CONDI-
TIONS THROUGHOUT THE AREA ARE FAVORABLE FOR FURTHER DEVELOPMENT.
UPPER LEVEL ANALYSIS INDICATES THE LLCC IS LOCATED EQUATORWARD OF A
SUBTROPICAL RIDGE AXIS, WHICH IS PROVIDING GOOD UPPER LEVEL DIVER-
GENCE AND MODERATE VERTICAL WIND SHEAR (VWS) NEAR THE LLCC. MAXIMUM
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 30 TO 35 KNOTS. MINIMUM SEA
LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1004 MB. BASED ON THE
INCREASING DEEP CONVECTION, DECREASING VWS, AND WELL DEFINED LLCC,
THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE
WITHIN THE NEXT 24 HOURS IS GOOD.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
030130Z.//
=========================================================================
WTXS31 PGTW 20100402 09:00z
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE 23S (TWENTYTHREE) WARNING NR 001//
RMKS/
1. TROPICAL CYCLONE 23S (TWENTYTHREE) WARNING NR 001
   01 ACTIVE TROPICAL CYCLONE IN SOUTHIO
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   020600Z --- NEAR 11.3S 92.5E
     MOVEMENT PAST SIX HOURS - 190 DEGREES AT 05 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
   WIND RADII VALID OVER OPEN WATER ONLY
   REPEAT POSIT: 11.3S 92.5E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   021800Z --- 12.2S 92.6E
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 015 NM NORTHEAST QUADRANT
                            015 NM SOUTHEAST QUADRANT
                            015 NM SOUTHWEST QUADRANT
                            015 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 155 DEG/ 06 KTS
    ---
   24 HRS, VALID AT:
   030600Z --- 13.2S 93.1E
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 020 NM NORTHEAST QUADRANT
                            020 NM SOUTHEAST QUADRANT
                            015 NM SOUTHWEST QUADRANT
                            015 NM NORTHWEST QUADRANT
   VECTOR TO 36 HR POSIT: 145 DEG/ 05 KTS
    ---
   36 HRS, VALID AT:
   031800Z --- 14.1S 93.7E
   MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 050 KT WINDS - 010 NM NORTHEAST QUADRANT
                            010 NM SOUTHEAST QUADRANT
                            010 NM SOUTHWEST QUADRANT
                            010 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 030 NM NORTHEAST QUADRANT
                            030 NM SOUTHEAST QUADRANT
                            025 NM SOUTHWEST QUADRANT
                            025 NM NORTHWEST QUADRANT
   VECTOR TO 48 HR POSIT: 145 DEG/ 07 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   040600Z --- 15.3S 94.6E
   MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 050 KT WINDS - 015 NM NORTHEAST QUADRANT
                            015 NM SOUTHEAST QUADRANT
                            015 NM SOUTHWEST QUADRANT
                            015 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT
                            040 NM SOUTHEAST QUADRANT
                            035 NM SOUTHWEST QUADRANT
                            035 NM NORTHWEST QUADRANT
   VECTOR TO 72 HR POSIT: 120 DEG/ 08 KTS
    ---
   72 HRS, VALID AT:
   050600Z --- 17.0S 97.5E
   MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 050 KT WINDS - 015 NM NORTHEAST QUADRANT
                            015 NM SOUTHEAST QUADRANT
                            015 NM SOUTHWEST QUADRANT
                            015 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT
                            040 NM SOUTHEAST QUADRANT
                            035 NM SOUTHWEST QUADRANT
                            035 NM NORTHWEST QUADRANT
   VECTOR TO 96 HR POSIT: 115 DEG/ 07 KTS
    ---
   LONG RANGE OUTLOOK:
   NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 250 NM
   ON DAY 4 AND 350 NM ON DAY 5... AND FOR INTENSITY
   NEAR 20 KT EACH DAY.
    ---
   96 HRS, VALID AT:
   060600Z --- 18.1S 100.1E
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   VECTOR TO 120 HR POSIT: 140 DEG/ 06 KTS
    ---
   120 HRS, VALID AT:
   070600Z --- 19.8S 101.6E
   MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
020900Z POSITION NEAR 11.5S 92.5E.
TROPICAL CYCLONE (TC) 23S, LOCATED APPROXIMATELY 260 NM WEST OF COCOS
ISLAND, AUSTRALIA, HAS TRACKED 5OUTHWARD AT 05 KNOTS OVER THE PAST
SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY SHOWS CONVECTIVE
BANDING HAS CONSOLIDATED AROUND THE LOW LEVEL CIRCULATION CENTER. THE
INITIAL POSITION IS EXTRAPOLATED FROM A 020022Z SSMIS MICROWAVE IMAGE
AND THE CURRENT INTENSITY IS BASED ON DVORAK ESTIMATES OF T2.5 FROM
PGTW AND KNES. UPPER LEVEL ANALYSIS INDICATES TC 23S IS JUST TO THE
NORTH OF A RIDGE AXIS IN AN AREA OF MODERATE EASTERLY VERTICAL WIND
SHEAR (VWS). THE CYCLONE IS EXPECTED TO TRACK SOUTH TO SOUTHEASTWARD
ALONG THE PERIPHERY OF A LOW- TO MID-LEVEL NEAR EQUATORIAL RIDGE TO
THE EAST OVER THE NEXT 48 HOURS. 22S WILL GRADUALLY INTENSIFY AS IT
TRACKS UNDER THE UPPER LEVEL RIDGE AXIS WHERE THE VWS VALUES ARE AT A
MINIMUM. AFTER TAU 72, THE SYSTEM WILL DEFLECT MORE EASTWARD AS A
MID-LATITUDE TROUGH APPROACHES FROM THE SOUTHWEST. TC 22S WILL
RAPIDLY WEAKEN WITH INCREASED VWS ASSOCIATED WITH THE STRONG
WESTERLIES. THE AVAILABLE NUMERIC MODELS ARE IN LOOSE AGREEMENT WITH
THIS TRACK FORECAST WITH THE EXCEPTION OF GFS, WHICH INITIALLY TRACKS
A WEAK VORTEX TO THE SOUTHWEST BEFORE MERGING WITH THE MAIN ENVELOPE
TO A SOUTHEAST TRAJECTORY. THE MODEL TRACKS SPREAD OUT SIGNIFICANTLY
IN SPEED AND DIRECTION AFTER TAU 72. THIS WARNING SUPERSEDES AND
CANCELS REF A, NAVMARFCSTCEN 020121Z APR 10 TROPICAL CYCLONE
FORMATION ALERT (WTXS21 PGTW 020130 ) MAXIMUM SIGNIFICANT WAVE HEIGHT
AT 020600Z IS 8 FEET. NEXT WARNINGS AT 022100Z AND 030900Z.//
=========================================================================
WTXS31 PGTW 20100402 21:00z
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE 23S (TWENTYTHRE) WARNING NR 002//
RMKS/
1. TROPICAL CYCLONE 23S (TWENTYTHRE) WARNING NR 002
   01 ACTIVE TROPICAL CYCLONE IN SOUTHIO
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   021800Z --- NEAR 12.7S 92.4E
     MOVEMENT PAST SIX HOURS - 180 DEGREES AT 07 KTS
     POSITION ACCURATE TO WITHIN 060 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT
                            040 NM SOUTHEAST QUADRANT
                            035 NM SOUTHWEST QUADRANT
                            035 NM NORTHWEST QUADRANT
   REPEAT POSIT: 12.7S 92.4E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   030600Z --- 13.4S 92.5E
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 045 NM NORTHEAST QUADRANT
                            045 NM SOUTHEAST QUADRANT
                            040 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 165 DEG/ 04 KTS
    ---
   24 HRS, VALID AT:
   031800Z --- 14.1S 92.7E
   MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 050 KT WINDS - 020 NM NORTHEAST QUADRANT
                            020 NM SOUTHEAST QUADRANT
                            020 NM SOUTHWEST QUADRANT
                            020 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
                            050 NM SOUTHEAST QUADRANT
                            045 NM SOUTHWEST QUADRANT
                            045 NM NORTHWEST QUADRANT
   VECTOR TO 36 HR POSIT: 155 DEG/ 04 KTS
    ---
   36 HRS, VALID AT:
   040600Z --- 14.8S 93.0E
   MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 064 KT WINDS - 015 NM NORTHEAST QUADRANT
                            015 NM SOUTHEAST QUADRANT
                            015 NM SOUTHWEST QUADRANT
                            015 NM NORTHWEST QUADRANT
   RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT
                            030 NM SOUTHEAST QUADRANT
                            030 NM SOUTHWEST QUADRANT
                            030 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 065 NM NORTHEAST QUADRANT
                            065 NM SOUTHEAST QUADRANT
                            055 NM SOUTHWEST QUADRANT
                            055 NM NORTHWEST QUADRANT
   VECTOR TO 48 HR POSIT: 145 DEG/ 05 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   041800Z --- 15.6S 93.6E
   MAX SUSTAINED WINDS - 080 KT, GUSTS 100 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 064 KT WINDS - 020 NM NORTHEAST QUADRANT
                            020 NM SOUTHEAST QUADRANT
                            020 NM SOUTHWEST QUADRANT
                            020 NM NORTHWEST QUADRANT
   RADIUS OF 050 KT WINDS - 035 NM NORTHEAST QUADRANT
                            035 NM SOUTHEAST QUADRANT
                            035 NM SOUTHWEST QUADRANT
                            035 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT
                            060 NM SOUTHEAST QUADRANT
                            060 NM SOUTHWEST QUADRANT
                            070 NM NORTHWEST QUADRANT
   VECTOR TO 72 HR POSIT: 120 DEG/ 04 KTS
    ---
   72 HRS, VALID AT:
   051800Z --- 16.5S 95.1E
   MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 050 KT WINDS - 025 NM NORTHEAST QUADRANT
                            025 NM SOUTHEAST QUADRANT
                            025 NM SOUTHWEST QUADRANT
                            025 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT
                            050 NM SOUTHEAST QUADRANT
                            050 NM SOUTHWEST QUADRANT
                            060 NM NORTHWEST QUADRANT
   VECTOR TO 96 HR POSIT: 125 DEG/ 02 KTS
    ---
   LONG RANGE OUTLOOK:
   NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 250 NM
   ON DAY 4 AND 350 NM ON DAY 5... AND FOR INTENSITY
   NEAR 20 KT EACH DAY.
    ---
   96 HRS, VALID AT:
   061800Z --- 17.0S 95.8E
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   VECTOR TO 120 HR POSIT: 155 DEG/ 02 KTS
    ---
   120 HRS, VALID AT:
   071800Z --- 17.6S 96.1E
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
022100Z POSITION NEAR 12.9S 92.4E.
TROPICAL CYCLONE (TC) 23S, LOCATED APPROXIMATELY 265 NM WEST OF THE
COCOS ISLANDS, AUSTRALIA, HAS TRACKED SOUTHWARD AT 07 KNOTS OVER THE
PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY AND RECENT
MICROWAVE IMAGERY INDICATE A CONSOLIDATING LOW-LEVEL CIRCULATION
CENTER (LLCC) WITH IMPROVED POLEWARD OUTFLOW. CONSEQUENTLY, DEEP
CONVECTION HAS EXPANDED OVER THE PAST 06 HOURS WITH THE LLCC LOCATED
ALONG THE NORTHEASTERN EDGE DUE TO MODERATE EASTERLY VERTICAL WIND
SHEAR. THE CURRENT INTENSITY IS BASED ON THE AVERAGE OF DVORAK
ESTIMATES RANGING FROM 35 TO 45 KNOTS. THERE IS MARGINAL CONFIDENCE
IN THE CURRENT POSITION AND MOTION BASED ON THE LACK OF STRONG
CONVECTIVE BANDING AND DEARTH OF HIGH-RESOLUTION MICROWAVE IMAGERY.
TC 23S IS CURRENTLY TRACKING SOUTHWARD ALONG THE WESTERN PERIPHERY
OF THE WEAK LOW- TO MID-LEVEL SUBTROPICAL RIDGE (STR). THE SYSTEM IS
EXPECTED TO TRACK INCREASINGLY SOUTHEASTWARD AS THE SOUTHERN
PERIPHERY OF THE STR ERODES WITH THE PASSAGE OF A MIDLATITUDE
SHORTWAVE TROUGH. TC 23S IS EXPECTED TO INTENSIFY UP TO A PEAK
INTENSITY OF 80 KNOTS NEAR TAU 48 DUE TO THE ENHANCED POLEWARD
OUTFLOW AND FAVORABLE SST AND OCEAN HEAT CONTENT. AFTER TAU 72, THE
SYSTEM SHOULD WEAKEN SIGNIFICANTLY DUE TO STRONG VERTICAL WIND SHEAR
PRODUCED BY A COMBINATION OF UPPER-LEVEL WESTERLIES AND LOW-LEVEL
EASTERLY FLOW (RIDGE BUILDING SOUTH OF THE SYSTEM AFTER THE FRONTAL
SYSTEM MOVES INTO WESTERN AUSTRALIA). IN THE EXTENDED TAUS, TC 23S
IS FORECAST TO WEAKEN BELOW 35 KNOTS AND DE-COUPLE AND WILL LIKELY
TURN WESTWARD UNDER THE STEERING INFLUENCE OF THE LOW-LEVEL RIDGE.
ALL OF THE DYNAMIC MODELS SUPPORT THIS TRACK WITH DIFFERENCES IN THE
TIMING OF THE TURN WESTWARD. THE UKMO MODEL REMAINS AN OUTLIER AND
INDICATES AN ERRONEOUS EASTWARD TRACK INTO THE STR AFTER TAU 48
THEREFORE THIS FORECAST IS POSITIONED WEST OF THE MODEL CONSENSUS
FROM TAU 72-120. THIS FORECAST REPRESENTS A SIGNIFICANT CHANGE FROM
THE PREVIOUS FORECAST BASED ON A LARGE SHIFT IN SEVERAL MODELS TO A
SLOWER, MORE REALISTIC TRACK. MAXIMUM SIGNIFICANT WAVE HEIGHT AT
021800Z IS 12 FEET. NEXT WARNINGS AT 030900Z AND 032100Z.//
=========================================================================
WTXS31 PGTW 20100403 09:00z
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE 23S (ROBYN) WARNING NR 003//
RMKS/
1. TROPICAL CYCLONE 23S (ROBYN) WARNING NR 003
   01 ACTIVE TROPICAL CYCLONE IN SOUTH IO
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   030600Z --- NEAR 13.0S 92.2E
     MOVEMENT PAST SIX HOURS - 180 DEGREES AT 03 KTS
     POSITION ACCURATE TO WITHIN 060 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 050 KT WINDS - 015 NM NORTHEAST QUADRANT
                            015 NM SOUTHEAST QUADRANT
                            015 NM SOUTHWEST QUADRANT
                            015 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 045 NM NORTHEAST QUADRANT
                            045 NM SOUTHEAST QUADRANT
                            040 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   REPEAT POSIT: 13.0S 92.2E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   031800Z --- 13.6S 92.2E
   MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 050 KT WINDS - 015 NM NORTHEAST QUADRANT
                            015 NM SOUTHEAST QUADRANT
                            015 NM SOUTHWEST QUADRANT
                            015 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
                            050 NM SOUTHEAST QUADRANT
                            045 NM SOUTHWEST QUADRANT
                            045 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 170 DEG/ 03 KTS
    ---
   24 HRS, VALID AT:
   040600Z --- 14.2S 92.3E
   MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 064 KT WINDS - 005 NM NORTHEAST QUADRANT
                            005 NM SOUTHEAST QUADRANT
                            005 NM SOUTHWEST QUADRANT
                            005 NM NORTHWEST QUADRANT
   RADIUS OF 050 KT WINDS - 020 NM NORTHEAST QUADRANT
                            020 NM SOUTHEAST QUADRANT
                            015 NM SOUTHWEST QUADRANT
                            015 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 055 NM NORTHEAST QUADRANT
                            055 NM SOUTHEAST QUADRANT
                            050 NM SOUTHWEST QUADRANT
                            050 NM NORTHWEST QUADRANT
   VECTOR TO 36 HR POSIT: 180 DEG/ 03 KTS
    ---
   36 HRS, VALID AT:
   041800Z --- 14.7S 92.3E
   MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 050 KT WINDS - 015 NM NORTHEAST QUADRANT
                            015 NM SOUTHEAST QUADRANT
                            015 NM SOUTHWEST QUADRANT
                            015 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
                            050 NM SOUTHEAST QUADRANT
                            045 NM SOUTHWEST QUADRANT
                            045 NM NORTHWEST QUADRANT
   VECTOR TO 48 HR POSIT: 195 DEG/ 02 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   050600Z --- 15.1S 92.2E
   MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 050 KT WINDS - 015 NM NORTHEAST QUADRANT
                            015 NM SOUTHEAST QUADRANT
                            015 NM SOUTHWEST QUADRANT
                            015 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 045 NM NORTHEAST QUADRANT
                            045 NM SOUTHEAST QUADRANT
                            040 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   VECTOR TO 72 HR POSIT: 215 DEG/ 01 KTS
    ---
   72 HRS, VALID AT:
   060600Z --- 15.5S 91.9E
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   RADIUS OF 034 KT WINDS - 025 NM NORTHEAST QUADRANT
                            025 NM SOUTHEAST QUADRANT
                            030 NM SOUTHWEST QUADRANT
                            030 NM NORTHWEST QUADRANT
   VECTOR TO 96 HR POSIT: 260 DEG/ 01 KTS
    ---
   LONG RANGE OUTLOOK:
   NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 250 NM
   ON DAY 4 AND 350 NM ON DAY 5... AND FOR INTENSITY
   NEAR 20 KT EACH DAY.
    ---
   96 HRS, VALID AT:
   070600Z --- 15.6S 91.3E
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
030900Z POSITION NEAR 13.2S 92.2E.
TROPICAL CYCLONE (TC) 23S, LOCATED APPROXIMATELY 280 NM WEST-
SOUTHWEST OF THE COCOS ISLANDS, AUSTRALIA, HAS SLOWED DOWN AND
TRACKED SOUTHWARD AT 03 KNOTS OVER THE PAST SIX HOURS. ANIMATED
WATER VAPOR IMAGERY SHOWS CONVECTIVE SYMMETRICAL BANDING HAVE
CONSOLIDATED OVER THE LOW-LEVEL CIRCULATION CENTER (LLCC) WITH
IMPROVED RADIAL OUTFLOW. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM
HAS DRIFTED UNDER THE RIDGE AXIS IN AN AREA OF LOW VERTICAL WIND
SHEAR (VWS). THE CURRENT INTENSITY IS BASED ON THE PGTW DVORAK
ESTIMATE OF T3.0. THE CURRENT POSITION IS EXTRAPOLATED FROM RECENT
MICROWAVE IMAGERY AND FROM A 030331Z ASCAT SCATTEROMETRY PASS. TC 23S
IS EXPECTED TO INTENSIFY IN THE SHORT TERM AND CONTINUE TRACKING
SLOWLY SOUTHWARD ALONG THE WESTERN PERIPHERY OF A WEAK STEERING RIDGE
TO THE EAST, OVER THE NEXT 48 TO 72 HOURS. AFTER TAU 72, THE SYSTEM
WILL BE EXPOSED TO STRONG WESTERLY VWS, DECOUPLING THE LLCC FROM THE
MAIN CONVECTION. THE REMNANT LOW WILL THEN DRIFT WESTWARD, STEERED BY
AN EASTWARD-MOVING SUBTROPICAL RIDGE TO THE SOUTH, AND DISSIPATE AS A
SIGNIFICANT TROPICAL CYCLONE OVER WATER BY TAU 96. THE MAJORITY OF
THE DYNAMIC MODELS SUPPORT THIS TRACK WITH DIFFERENCES IN THE SPEED
AND TIMING OF THE WESTWARD TRACK. WBAR AND GFS FORECAST THE SYSTEM TO
SURVIVE THE STRONG WESTERLY VWS AND TRACK SOUTHEASTWARD WITH THE
MID-LEVEL FLOW. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 030600Z IS 14
FEET. NEXT WARNINGS AT 032100Z AND 040900Z.//
=========================================================================
WTXS31 PGTW 20100403 21:00z
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE 23S (ROBYN) WARNING NR 004//
RMKS/
1. TROPICAL CYCLONE 23S (ROBYN) WARNING NR 004
   01 ACTIVE TROPICAL CYCLONE IN SOUTHIO
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   031800Z --- NEAR 14.0S 92.5E
     MOVEMENT PAST SIX HOURS - 170 DEGREES AT 05 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
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
                            050 NM SOUTHEAST QUADRANT
                            040 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   REPEAT POSIT: 14.0S 92.5E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   040600Z --- 14.8S 92.3E
   MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 050 KT WINDS - 020 NM NORTHEAST QUADRANT
                            020 NM SOUTHEAST QUADRANT
                            020 NM SOUTHWEST QUADRANT
                            020 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 055 NM NORTHEAST QUADRANT
                            055 NM SOUTHEAST QUADRANT
                            045 NM SOUTHWEST QUADRANT
                            045 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 185 DEG/ 04 KTS
    ---
   24 HRS, VALID AT:
   041800Z --- 15.6S 92.2E
   MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 050 KT WINDS - 025 NM NORTHEAST QUADRANT
                            025 NM SOUTHEAST QUADRANT
                            025 NM SOUTHWEST QUADRANT
                            025 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT
                            060 NM SOUTHEAST QUADRANT
                            050 NM SOUTHWEST QUADRANT
                            050 NM NORTHWEST QUADRANT
   VECTOR TO 36 HR POSIT: 175 DEG/ 04 KTS
    ---
   36 HRS, VALID AT:
   050600Z --- 16.4S 92.3E
   MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 050 KT WINDS - 020 NM NORTHEAST QUADRANT
                            020 NM SOUTHEAST QUADRANT
                            020 NM SOUTHWEST QUADRANT
                            020 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 055 NM NORTHEAST QUADRANT
                            055 NM SOUTHEAST QUADRANT
                            040 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   VECTOR TO 48 HR POSIT: 145 DEG/ 02 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   051800Z --- 16.7S 92.5E
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT
                            040 NM SOUTHEAST QUADRANT
                            030 NM SOUTHWEST QUADRANT
                            030 NM NORTHWEST QUADRANT
   VECTOR TO 72 HR POSIT: 225 DEG/ 02 KTS
    ---
   72 HRS, VALID AT:
   061800Z --- 17.2S 92.0E
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   VECTOR TO 96 HR POSIT: 260 DEG/ 03 KTS
    ---
   LONG RANGE OUTLOOK:
   NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 250 NM
   ON DAY 4 AND 350 NM ON DAY 5... AND FOR INTENSITY
   NEAR 20 KT EACH DAY.
    ---
   96 HRS, VALID AT:
   071800Z --- 17.4S 90.7E
   MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
032100Z POSITION NEAR 14.2S 92.5E.
TROPICAL CYCLONE (TC) 23S, LOCATED APPROXIMATELY 280 NM
WEST-SOUTHWEST OF THE COCOS ISLANDS, AUSTRALIA, HAS TRACKED
SOUTHWARD AT 05 KNOTS OVER THE PAST SIX HOURS. ANIMATED
INFRARED SATELLITE IMAGERY AND A 031808Z TRMM 37 GHZ IMAGE
INDICATE SLIGHT WEAKENING OVER THE PAST 12 HOURS WITH A
DEFINED LOW-LEVEL CIRCULATION CENTER (LLCC) SHEARED EAST
OF THE DEEP CONVECTION. THE CURRENT POSITION IS BASED
PRIMARILY ON THIS TRMM IMAGE WITH GOOD CONFIDENCE. THERE
IS MARGINAL CONFIDENCE IN THE EXACT 12-HOUR MOTION BASED
ON THE SHEARED NATURE OF THE SYSTEM BUT TC 23S IS TRACKING
GENERALLY SOUTHWARD ALONG THE WESTERN PERIPHERY OF THE
WEAK LOW- TO MID-LEVEL SUBTROPICAL RIDGE (STR). THE CURRENT
INTENSITY IS SLIGHTLY HIGHER THAN THE FINAL-T DVORAK
ESTIMATES OF 45 KNOTS BASED ON A CI OF 55 KNOTS FROM PGTW.
THIS MOTION SHOULD CONTINUE THROUGH TAU 36 WITH A MORE SOUTH-
SOUTHEASTWARD, SLOWER TRACK EXPECTED NEAR TAU 48 AS A
RESULT OF AN APPROACHING MIDLATITUDE SHORTWAVE TROUGH AND
INCREASING VERTICAL WIND SHEAR (VWS). TC 23S IS FORECAST
TO WEAKEN RAPIDLY UNDER STRONG VWS AND WILL TURN WESTWARD
UNDER THE STEERING INFLUENCE OF THE LOW-LEVEL RIDGE
SOUTH OF THE SYSTEM. THERE IS SIGNIFICANT UNCERTAINTY
IN THE TIMING OF THIS WESTWARD TURN, HOWEVER, ALL AVAILABLE
MODEL TRACKERS, EXCEPT WBAR, SUPPORT THE TURN BETWEEN
15-17S. WBAR INDICATES A RE-CURVE SCENARIO WHICH APPEARS
HIGHLY UNLIKELY DUE TO THE STRONG VWS AND BROAD LOW-LEVEL
HIGH EXPECTED TO BUILD SOUTH OF THE SYSTEM AFTER TAU 24.
THIS FORECAST IS IN CLOSE AGREEMENT WITH THE MODEL CONSENSUS.
MAXIMUM SIGNIFICANT WAVE HEIGHT AT 031800Z IS 16 FEET.
NEXT WARNINGS AT 040900Z AND 042100Z.//
=========================================================================
WTXS31 PGTW 20100404 09:00z
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE 23S (ROBYN) WARNING NR 005//
RMKS/
1. TROPICAL CYCLONE 23S (ROBYN) WARNING NR 005
   01 ACTIVE TROPICAL CYCLONE IN SOUTHIO
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   040600Z --- NEAR 15.2S 92.1E
     MOVEMENT PAST SIX HOURS - 200 DEGREES AT 06 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
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
                            050 NM SOUTHEAST QUADRANT
                            040 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   REPEAT POSIT: 15.2S 92.1E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   041800Z --- 16.2S 92.0E
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
                            050 NM SOUTHEAST QUADRANT
                            040 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 170 DEG/ 03 KTS
    ---
   24 HRS, VALID AT:
   050600Z --- 16.7S 92.1E
   MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 050 KT WINDS - 005 NM NORTHEAST QUADRANT
                            005 NM SOUTHEAST QUADRANT
                            005 NM SOUTHWEST QUADRANT
                            005 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 055 NM NORTHEAST QUADRANT
                            055 NM SOUTHEAST QUADRANT
                            045 NM SOUTHWEST QUADRANT
                            045 NM NORTHWEST QUADRANT
   VECTOR TO 36 HR POSIT: 160 DEG/ 02 KTS
    ---
   36 HRS, VALID AT:
   051800Z --- 17.0S 92.2E
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
                            050 NM SOUTHEAST QUADRANT
                            040 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   VECTOR TO 48 HR POSIT: 225 DEG/ 01 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   060600Z --- 17.2S 92.0E
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT
                            040 NM SOUTHEAST QUADRANT
                            030 NM SOUTHWEST QUADRANT
                            030 NM NORTHWEST QUADRANT
   VECTOR TO 72 HR POSIT: 265 DEG/ 03 KTS
    ---
   72 HRS, VALID AT:
   070600Z --- 17.3S 90.9E
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
040900Z POSITION NEAR 15.5S 92.1E.
TROPICAL CYCLONE (TC) 23S, LOCATED APPROXIMATELY 335 NM SOUTHWEST
OF THE COCOS ISLANDS, AUSTRALIA, HAS TRACKED SOUTH-SOUTHWESTWARD AT
05 KNOTS OVER THE PAST SIX HOURS. ANIMATED WATER VAPOR IMAGERY SHOWS
THE SYSTEM HAS MAINTAINED OVERALL CONVECTIVE BANDING AND OUTFLOW
ALTHOUGH IT HAS BEGUN TO ELONGATE ON THE SOUTHWEST QUADRANT, AN
INDICATION OF INCREASING VERTICAL WIND SHEAR (VWS). THE INITIAL
POSITION IS EXTRAPOLATED FROM A 040311Z AMSU-B MICROWAVE IMAGE AND
THE INITIAL INTENSITY IS AVERAGED FROM DVORAK ESTIMATES RANGING FROM
T3.0 TO T3.5 FROM PGTW/KNES AND APRF, RESPECTIVELY. TC 23S IS
EXPECTED TO CONTINUE TRACKING GENERALLY SOUTHWARD ALONG THE WESTERN
PERIPHERY OF THE WEAK LOW- TO MID-LEVEL SUBTROPICAL RIDGE (STR) UP TO
TAU 24 BEFORE IT GETS DEFLECTED MOMENTARILY TO THE SOUTHEAST IN
RESPONSE TO AN APPROACHING MID-LATITUDE SHORTWAVE TROUGH AND
INCREASING WESTERLY VWS. THE HIGH VWS WILL ERODE TC ROBYN AND CAUSE
IT TO WEAKEN RAPIDLY. THE REMNANT LOW LEVEL FEATURE WILL THEN TURN
WESTWARD UNDER THE STEERING INFLUENCE OF THE LOW-LEVEL RIDGE SOUTH OF
THE SYSTEM. THE AVAILABLE MODEL GUIDANCE, WITH THE EXCEPTION OF WBAR,
SUPPORT THE WESTWARD TURN WITH NOTABLE DIFFERENCES IN SPEED AND
TIMING. THIS TRACK FORECAST IS IN CLOSE AGREEMENT WITH THE MODEL
CONSENSUS. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 040600Z IS 16 FEET.
NEXT WARNINGS AT 042100Z AND 050900Z.//
=========================================================================
WTXS31 PGTW 20100404 21:00z
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE 23S (ROBYN) WARNING NR 006//
RMKS/
1. TROPICAL CYCLONE 23S (ROBYN) WARNING NR 006
   01 ACTIVE TROPICAL CYCLONE IN SOUTHIO
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   041800Z --- NEAR 15.4S 91.0E
     MOVEMENT PAST SIX HOURS - 240 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
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT
                            045 NM SOUTHEAST QUADRANT
                            045 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 065 NM NORTHEAST QUADRANT
                            075 NM SOUTHEAST QUADRANT
                            080 NM SOUTHWEST QUADRANT
                            065 NM NORTHWEST QUADRANT
   REPEAT POSIT: 15.4S 91.0E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   050600Z --- 15.8S 90.5E
   MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 064 KT WINDS - 025 NM NORTHEAST QUADRANT
                            025 NM SOUTHEAST QUADRANT
                            025 NM SOUTHWEST QUADRANT
                            025 NM NORTHWEST QUADRANT
   RADIUS OF 050 KT WINDS - 045 NM NORTHEAST QUADRANT
                            050 NM SOUTHEAST QUADRANT
                            050 NM SOUTHWEST QUADRANT
                            045 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 075 NM NORTHEAST QUADRANT
                            080 NM SOUTHEAST QUADRANT
                            085 NM SOUTHWEST QUADRANT
                            070 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 235 DEG/ 02 KTS
    ---
   24 HRS, VALID AT:
   051800Z --- 16.0S 90.2E
   MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT
                            045 NM SOUTHEAST QUADRANT
                            040 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 065 NM NORTHEAST QUADRANT
                            075 NM SOUTHEAST QUADRANT
                            070 NM SOUTHWEST QUADRANT
                            060 NM NORTHWEST QUADRANT
   VECTOR TO 36 HR POSIT: 240 DEG/ 02 KTS
    ---
   36 HRS, VALID AT:
   060600Z --- 16.2S 89.8E
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 055 NM NORTHEAST QUADRANT
                            065 NM SOUTHEAST QUADRANT
                            060 NM SOUTHWEST QUADRANT
                            055 NM NORTHWEST QUADRANT
   VECTOR TO 48 HR POSIT: 250 DEG/ 05 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   061800Z --- 16.5S 88.8E
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   RADIUS OF 034 KT WINDS - 045 NM NORTHEAST QUADRANT
                            055 NM SOUTHEAST QUADRANT
                            045 NM SOUTHWEST QUADRANT
                            045 NM NORTHWEST QUADRANT
   VECTOR TO 72 HR POSIT: 260 DEG/ 06 KTS
    ---
   72 HRS, VALID AT:
   071800Z --- 16.9S 86.5E
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
042100Z POSITION NEAR 15.5S 90.9E.
TROPICAL CYCLONE (TC) 23S, LOCATED APPROXIMATELY 395 NM WEST-
SOUTHWEST OF THE COCOS ISLANDS, AUSTRALIA, HAS TRACKED WEST-
SOUTHWESTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED
SATELLITE IMAGERY AND A 04/1721Z TRMM IMAGE INDICATE THAT THE SYSTEM
HAS CONSOLIDATED OVER THE PAST 12 HOURS WITH TIGHTLY-CURVED BANDING
EVIDENT AND IMPROVED POLEWARD OUTFLOW AHEAD OF A DEEPENING
MIDLATITUDE SHORTWAVE TROUGH. THERE IS GOOD CONFIDENCE IN THE
CURRENT POSITION AND MOTION BASED ON THE TRMM 37 GHZ MICROWAVE EYE
FEATURE AND THE 04/1132Z SSMIS IMAGE. ANIMATED WATER VAPOR IMAGERY
INDICATES DECREASED OUTFLOW WEST OF THE SYSTEM DUE TO STRONGER
WESTERLY FLOW ASSOCIATED WITH THE SHORTWAVE TROUGH, AND IMPROVED
POLEWARD OUTFLOW OVER THE SOUTH SEMI-CIRCLE. THE CURRENT INTENSITY
IS BASED ON AN AVERAGE OF DVORAK ESTIMATES RANGING FROM 55 TO 65
KNOTS AND IS CONSISTENT WITH THE LATEST SATCON ESTIMATE OF 68 KNOTS.
TC 23S HAS ACCELERATED AND IS TRACKING ALONG THE NORTHWESTERN
PERIPHERY OF A FINGER OF THE MID-LEVEL SUBTROPICAL RIDGE (STR).
NUMERICAL GUIDANCE HAS, IN GENERAL, OVER FORECAST THE STRENGTH OF
THE MIDLATITUDE TROUGH AND ERRONEOUSLY WEAKENED THE STR RESULTING IN
A PROLONGED SOUTHEASTWARD TRACK. THE CURRENT SUITE OF MODEL TRACKERS
NOW INDICATES WEAK INTERACTION WITH THE TROUGH AND EITHER A SLOW-
DOWN OR SLIGHT TURN SOUTHWARD IN THE EARLY TAUS THEN A WESTWARD
TRACK THROUGH THE REMAINDER OF THE FORECAST PERIOD UNDER THE
STEERING INFLUENCE OF A BUILDING STR TO THE SOUTH. THIS REMAINS THE
LIKELIEST SCENARIO. THE ECMWF, GFDN, NOGAPS, GFS, TC-LAPS AND UKMO
TRACKERS SUPPORT THIS SCENARIO. WBAR IS THE OUTLIER AND DEPICTS AN
UNLIKELY RE-CURVE SCENARIO AND IS SKEWING THE MODEL CONSENSUS
SOUTHEASTWARD AND SLOWER, THEREFORE, THIS FORECAST IS NORTH OF THE
CONSENSUS AND FASTER. TC 23S IS EXPECTED TO PEAK AT 65 TO 70 KNOTS
BUT SHOULD WEAKEN QUICKLY DUE TO INCREASING WESTERLY VERTICAL WIND
SHEAR. THE SYSTEM IS FORECAST TO DISSIPATE BY TAU 72. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 041800Z IS 17 FEET. NEXT WARNINGS AT
050900Z AND 052100Z.//
=========================================================================
WTXS31 PGTW 20100405 09:00z
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE 23S (ROBYN) WARNING NR 007//
RMKS/
1. TROPICAL CYCLONE 23S (ROBYN) WARNING NR 007
   01 ACTIVE TROPICAL CYCLONE IN SOUTHIO
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   050600Z --- NEAR 16.1S 92.0E
     MOVEMENT PAST SIX HOURS - 120 DEGREES AT 06 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
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 050 KT WINDS - 025 NM NORTHEAST QUADRANT
                            030 NM SOUTHEAST QUADRANT
                            030 NM SOUTHWEST QUADRANT
                            025 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 055 NM NORTHEAST QUADRANT
                            065 NM SOUTHEAST QUADRANT
                            065 NM SOUTHWEST QUADRANT
                            065 NM NORTHWEST QUADRANT
   REPEAT POSIT: 16.1S 92.0E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   051800Z --- 16.3S 92.2E
   MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 050 KT WINDS - 025 NM NORTHEAST QUADRANT
                            030 NM SOUTHEAST QUADRANT
                            030 NM SOUTHWEST QUADRANT
                            025 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 055 NM NORTHEAST QUADRANT
                            065 NM SOUTHEAST QUADRANT
                            065 NM SOUTHWEST QUADRANT
                            065 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 180 DEG/ 02 KTS
    ---
   24 HRS, VALID AT:
   060600Z --- 16.7S 92.2E
   MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 050 KT WINDS - 020 NM NORTHEAST QUADRANT
                            025 NM SOUTHEAST QUADRANT
                            025 NM SOUTHWEST QUADRANT
                            020 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
                            060 NM SOUTHEAST QUADRANT
                            060 NM SOUTHWEST QUADRANT
                            050 NM NORTHWEST QUADRANT
   VECTOR TO 36 HR POSIT: 260 DEG/ 06 KTS
    ---
   36 HRS, VALID AT:
   061800Z --- 16.9S 91.0E
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
                            060 NM SOUTHEAST QUADRANT
                            060 NM SOUTHWEST QUADRANT
                            050 NM NORTHWEST QUADRANT
   VECTOR TO 48 HR POSIT: 260 DEG/ 07 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   070600Z --- 17.1S 89.5E
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   RADIUS OF 034 KT WINDS - 045 NM NORTHEAST QUADRANT
                            055 NM SOUTHEAST QUADRANT
                            045 NM SOUTHWEST QUADRANT
                            045 NM NORTHWEST QUADRANT
   VECTOR TO 72 HR POSIT: 260 DEG/ 07 KTS
    ---
   72 HRS, VALID AT:
   080600Z --- 17.5S 86.7E
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
050900Z POSITION NEAR 16.1S 92.0E.
TROPICAL CYCLONE (TC) 23S (ROBYN), LOCATED APPROXIMATELY 370 NM
SOUTHWEST OF THE COCOS ISLANDS, AUSTRALIA, HAS TRACKED EAST-
SOUTHEASTWARD AT 06 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTI-
SPECTRAL SATELLITE IMAGERY SHOWS DEEP CONVECTION HAS DECREASED OVER
THE PAST 12 HOURS HOWEVER, THE LLCC REMAINS WELL ORGANIZED BASED ON A
050250Z ASCAT PASS SHOWING THE STRONGEST WINDS LOCATED IN THE SOUTH-
WESTERN QUADRANT OF THE LLCC, AT 45 TO 50 KNOTS. THE CURRENT INTEN-

SITY OF 60 KNOTS IS BASED ON DVORAK INTENSITY ESTIMATES RANGING FROM
55 TO 75 KNOTS. UPPER LEVEL ANALYSIS INDICATES THE MIDLATITUDE SHORT-
WAVE TROUGH FROM THE PREVIOUS FORECAST CONTINUES TO TRACK EASTWARD,
AND IS CURRENTLY LOCATED TO THE SOUTH OF TC 23S. THE TROUGH CONTINUES
TO CREATE STRONG WESTERLY FLOW POLEWARD OF TC 23S HELPING TO VENT THE
SYSTEM. AS ROBYN MOVES SOUTHEASTWARD IT HAS STARTED TO MOVE INTO A
HIGHER VERTICAL WIND SHEAR (VWS) ENVIRONMENT AND IS NOW POLEWARD OF
THE SUBTROPICAL RIDGE (STR) AXIS. THE MIDLATITUDE TROUGH HAS WEAKENED
THE STR AND WILL KEEP ROBYN SLOWLY TRACKING TO THE SOUTHEAST OVER THE
NEXT 24 HOURS UNTIL A DEVELOPING MIDLATITUDE STR BUILDS TO THE SOUTH
CAUSING A SHIFT IN THE TRACK TO THE WEST-SOUTHWEST AND A TRACK SPEED
INCREASE. INCREASING VWS WILL BEGIN TO QUICKLY WEAKEN TC 23S WITH
DISSIPATION EXPECTED BY TAU 72. MAXIMUM SIGNIFICANT WAVE HEIGHT AT
050600Z IS 18 FEET. NEXT WARNINGS AT 052100Z AND 060900Z.//
=========================================================================
WTXS31 PGTW 20100405 21:00z
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE 23S (ROBYN) WARNING NR 008//
RMKS/
1. TROPICAL CYCLONE 23S (ROBYN) WARNING NR 008
   01 ACTIVE TROPICAL CYCLONE IN SOUTHIO
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   051800Z --- NEAR 16.2S 92.2E
     MOVEMENT PAST SIX HOURS - 090 DEGREES AT 01 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
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 065 NM NORTHEAST QUADRANT
                            075 NM SOUTHEAST QUADRANT
                            070 NM SOUTHWEST QUADRANT
                            060 NM NORTHWEST QUADRANT
   REPEAT POSIT: 16.2S 92.2E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   060600Z --- 16.2S 91.6E
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 055 NM NORTHEAST QUADRANT
                            065 NM SOUTHEAST QUADRANT
                            060 NM SOUTHWEST QUADRANT
                            050 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 255 DEG/ 04 KTS
    ---
   24 HRS, VALID AT:
   061800Z --- 16.4S 90.8E
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   VECTOR TO 36 HR POSIT: 250 DEG/ 06 KTS
    ---
   36 HRS, VALID AT:
   070600Z --- 16.8S 89.6E
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
052100Z POSITION NEAR 16.2S 92.1E.
TROPICAL CYCLONE (TC) 23S (ROBYN), LOCATED APPROXIMATELY 365 NM
SOUTHWEST OF THE COCOS ISLANDS, HAS TRACKED EASTWARD AT 01 KNOT OVER
THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY SHOWS WANING
DEEP CONVECTION THAT IS BECOMING MORE DISORGANIZED DUE TO 20-30
KNOTS OF NORTHWESTERLY VERTICAL WIND SHEAR. ACCORDINGLY, DVORAK
ESTIMATES FROM PGTW, KNES, AND APRF HAVE DROPPED OVER THE LAST 12
HOURS AND NOW RANGE FROM 30 TO 55 KNOTS. THE CURRENT POSITION IS
BASED ON A 051854Z AMSU MICROWAVE IMAGE WHICH SUGGESTS THE LOW LEVEL
CIRCULATION CENTER (LLCC) IS EXPOSED AND LOCATED TO THE NORTHWEST OF
THE MAIN CONVECTION. AS TC 23S WEAKENS, IT HAS SLOWED IN FORWARD
TRACK SPEED DUE TO COMPETING STEERING INFLUENCES AT THE LOW TO MID
LEVELS. OVER THE NEXT 12 HOURS, TC ROBYN IS EXPECTED TO CONTINUE
WEAKENING AS IT LOSES POLEWARD OUTFLOW (PREVIOUSLY ENHANCED BY A
PASSING MID-LATITUDE TROUGH) AND START TRACKING WESTWARD UNDER THE
INFLUENCE OF A LOW- TO MID-LEVEL SUBTROPICAL RIDGE BUILDING IN FROM
THE WEST. BY TAU 36, THE SYSTEM IS EXPECTED TO DISSIPATE AS A
SIGNIFICANT TROPICAL CYCLONE AS IT SUCCUMBS TO EXCESSIVE VERTICAL
WIND SHEAR AND LACK OF A VENTING MECHANISM. THE NUMERICAL MODEL AIDS
ARE IN GOOD AGREEMENT WITH A WESTWARD TRACK AND THIS FORECAST IS
SLOWER THAN THE JTWC CONSENSUS IN ORDER TO REFLECT UNCERTAINTY IN
TRACK SPEED OVER THE NEXT 06 HOURS AS THE SYSTEM MAKES ITS TURN TO
THE WEST. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 051800Z IS 18 FEET.
NEXT WARNINGS AT 060900Z AND 062100Z.//
=========================================================================
WTXS31 PGTW 20100406 09:00z
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE 23S (ROBYN) WARNING NR 009//
RMKS/
1. TROPICAL CYCLONE 23S (ROBYN) WARNING NR 009
   01 ACTIVE TROPICAL CYCLONE IN SOUTHIO
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   060600Z --- NEAR 15.5S 91.7E
     MOVEMENT PAST SIX HOURS - 340 DEGREES AT 03 KTS
     POSITION ACCURATE TO WITHIN 020 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   REPEAT POSIT: 15.5S 91.7E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   061800Z --- 15.4S 91.1E
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   VECTOR TO 24 HR POSIT: 260 DEG/ 03 KTS
    ---
   24 HRS, VALID AT:
   070600Z --- 15.5S 90.4E
   MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
060900Z POSITION NEAR 15.5S 91.6E.
TROPICAL CYCLONE (TC) 23S (ROBYN), LOCATED APPROXIMATELY 365 NM
SOUTHWEST OF THE COCOS ISLANDS, HAS TRACKED NORTH-NORTHWESTWARD AT 03
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY SHOWS THE LOW LEVEL CIRCULATION CENTER (LLCC) IS FULLY
EXPOSED, WITH CONVECTION SHEARED 140 NM TO THE SOUTHEAST. BASED ON
THE RECENT DVORAK ESTIMATES FROM PGTW, TC 23S IS ESTIMATED TO BE AT
35 KNOTS. THE LLCC STILL REMAINS WELL ORGANIZED BUT IS EXPECTED TO
CONTINUE WEAKENING OVER THE NEXT 24 HOURS, WITH FULL DISSIPATION BY
TAU 24. THE UPPER LEVEL ENVIRONMENT IS EXPECTED TO REMAIN UNFAVORABLE
FOR DEVELOPMENT, HOWEVER IF THE VERTICAL WIND SHEAR GRADIENT SHOULD
DECREASE IN THE NEXT 24 HOURS, DEEP CONVECTION COULD BEGIN BUILDING
BACK OVER THE LLCC, LEADING TO THE RE-ISSUANCE OF WARNINGS. BASED ON
THE HIGH VWS AND CONTINUED WEAKENING TREND OVER THE PAST 24 HOURS,
THIS IS THE FINAL WARNING ON THIS SYSTEM BY THE JOINT TYPHOON WARNING
CENTER (NAVMARFCSTCEN). THE SYSTEM WILL BE CLOSELY MONITORED FOR
SIGNS OF REGENERATION. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 060600Z IS
15 FEET.//

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


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Document: tropical_cyclone_robyn_jtwc_advisories.htm Updated: 2 May 2017