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

WTXS21 PGTW 20100422 08:30z
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE FORMATION ALERT REISSUED 210821APR2010//
REF/A/MSG/NAVMARFCSTCEN PEARL HARBOR HI/210821APR2010//
AMPN/REF A IS A TROPICAL CYCLONE FORMATIOIN ALERT.//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
125 NM EITHER SIDE OF A LINE FROM 11.8S 116.0E TO 14.2S 113.1E
WITHIN THE NEXT 12 TO 24 HOURS.  AVAILABLE DATA DOES NOT JUSTIFY
ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME.
WINDS IN THE AREA ARE ESTIMATED TO BE 25 TO 30 KNOTS. METSAT IM-
AGERY AT 220530Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 12.3S 115.8E.  THE SYSTEM IS MOVING SOUTH-SOUTHWESTWARD AT
05 KNOTS.
2. REMARKS: THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 10.1S
116.4E, IS NOW LOCATED NEAR 12.3S 115.8E, APPROXIMATELY 500 NM NORTH-
NORTHWEST OF PORT HEADLAND, AUSTRALIA. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY SHOWS CURVED CONVECTIVE BANDING AROUND A LOW LEVEL
CIRCULATION CENTER (LLCC) AND A 212330Z SSMIS MICROWAVE IMAGE
DEPICTS MINIMAL DEEP CONVECTION WEST OF THE LLCC. INITIAL INTENSITY
IS BASED ON DVORAK ESTIMATES OF 30 KNOTS FROM PGTW, KNES, AND APRF,
IN ADDITION TO A 220158Z ASCAT PASS INDICATING 25 TO 30 KNOTS AROUND
THE LLCC. UPPER LEVEL ANALYSIS SHOWS AN ANTICYCLONE TO THE EAST IS
PROVIDING GOOD OUTFLOW AND AN UPPER LEVEL TROUGH TO THE SOUTHWEST IS
PROVIDING A POLEWARD OUTFLOW CHANNEL. THE SYSTEM IS LOCATED IN AN
AREA OF LOW VERTICAL WIND SHEAR (VWS) EQUATORWARD OF THE SUBTROPICAL
RIDGE AXIS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25 TO
30 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1000
MB. DUE TO GOOD OUTFLOW, LOW VWS, AND HIGH OCEAN HEAT CONTENT, THE
POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE
WITHIN THE NEXT 24 HOURS REMAINS GOOD. THIS SUPERSEDES REF A.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
230830Z.//
=========================================================================
WTXS31 PGTW 20100422 15:00z
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE 24S (TWENTYFOUR) WARNING NR 001//
REF/A/NAVMARFCSTCEN PEARL HARBOR HI/220821ZAPR10//
AMPN/TROPICAL CYCLONE FORMATION ALERT//
RMKS/
1. TROPICAL CYCLONE 24S (TWENTYFOUR) 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:
   221200Z --- NEAR 12.8S 115.7E
     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: 12.8S 115.7E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   230000Z --- 13.9S 114.5E
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT
                            045 NM SOUTHEAST QUADRANT
                            045 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 245 DEG/ 08 KTS
    ---
   24 HRS, VALID AT:
   231200Z --- 14.6S 113.1E
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 045 NM NORTHEAST QUADRANT
                            055 NM SOUTHEAST QUADRANT
                            055 NM SOUTHWEST QUADRANT
                            045 NM NORTHWEST QUADRANT
   VECTOR TO 36 HR POSIT: 250 DEG/ 06 KTS
    ---
   36 HRS, VALID AT:
   240000Z --- 15.0S 111.9E
   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 - 050 NM NORTHEAST QUADRANT
                            060 NM SOUTHEAST QUADRANT
                            060 NM SOUTHWEST QUADRANT
                            050 NM NORTHWEST QUADRANT
   VECTOR TO 48 HR POSIT: 255 DEG/ 05 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   241200Z --- 15.3S 110.9E
   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
                            065 NM SOUTHEAST QUADRANT
                            065 NM SOUTHWEST QUADRANT
                            055 NM NORTHWEST QUADRANT
   VECTOR TO 72 HR POSIT: 260 DEG/ 05 KTS
    ---
   72 HRS, VALID AT:
   251200Z --- 15.6S 109.0E
   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
                            065 NM SOUTHEAST QUADRANT
                            065 NM SOUTHWEST QUADRANT
                            055 NM NORTHWEST QUADRANT
   VECTOR TO 96 HR POSIT: 275 DEG/ 12 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:
   261200Z --- 15.3S 104.2E
   MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   VECTOR TO 120 HR POSIT: 270 DEG/ 14 KTS
    ---
   120 HRS, VALID AT:
   271200Z --- 15.2S 98.3E
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
REMARKS:
221500Z POSITION NEAR 13.1S 115.4E.
TROPICAL CYCLONE (TC) 24S, LOCATED APPROXIMATELY 570 NM NORTH OF
LEARMONTH, AUSTRALIA, HAS TRACKED SOUTHWARD AT 05 KNOTS DURING THE
PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY SHOWS INCREASED
CENTRAL CONVECTION AND A 220925Z SSMIS MICROWAVE IMAGE DEPICTS
IMPROVED CONVECTIVE BANDING AROUND A LOW LEVEL CIRCULATION CENTER
(LLCC). INITIAL INTENSITY IS BASED ON PGTW AND APRF DVORAK ESTIMATES
OF 35 KNOTS. UPPER LEVEL ANALYSIS INDICATES TC 24S IS LOCATED
BENEATH THE SUBTROPICAL RIDGE AXIS IN AN AREA OF LOW VERTICAL WIND
SHEAR (VWS) AND GOOD OUTFLOW. AN UPPER LEVEL TROUGH LOCATED TO THE
SOUTHWEST IS SUPPORTING A POLEWARD OUTFLOW CHANNEL. TC 24S IS
CURRENTLY TRACKING SOUTHWARD ALONG THE NORTHWESTERN PERIPHERY OF A
SUBTROPICAL RIDGE (STR). AS THE STR BUILDS BACK IN WITH THE PASSING
OF THE UPPER LEVEL TROUGH, TC 24S WILL BEGIN TO TURN WESTWARD AND
EVENTUALLY INCREASE IN SPEED AS THE STR BECOMES STRONGER AFTER TAU
72. INTENSITIES ARE FORECAST TO INCREASE, HOWEVER AS THE SYSTEM
MOVES FARTHER SOUTHWESTWARD, VERTICAL WIND SHEAR WILL INCREASE AND
AFTER TAU 72, TC 24S SHOULD BEGIN TO WEAKEN. AVAILABLE NUMERICAL
MODEL GUIDANCE IS IN GOOD AGREEMENT WITH THE SOUTHWESTWARD TO
WESTWARD TRACK, EXCEPT FOR WBAR THAT TRACKS THE SYSTEM SOUTHWARD.
THIS TURN SOUTHWARD IS NOT LIKELY BECAUSE THE STR IS EXPECTED TO
STRENGTHEN AND CONTINUE TRACKING TC 24S WESTWARD. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 221200Z IS 9 FEET. NEXT WARNINGS AT
230300Z AND 231500Z. THIS WARNING SUPERSEDES AND CANCELS REF A,
NAVMARFCSTCEN 220821Z APR 10 TROPICAL CYCLONE FORMATION ALERT
=========================================================================
WTXS31 PGTW 20100423 03:00z
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE 24S (SEAN) WARNING NR 002//
RMKS/
1. TROPICAL CYCLONE 24S (TWENTYFOUR) 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:
   230000Z --- NEAR 13.6S 113.8E
     MOVEMENT PAST SIX HOURS - 245 DEGREES AT 07 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 - 045 NM NORTHEAST QUADRANT
                            050 NM SOUTHEAST QUADRANT
                            050 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   REPEAT POSIT: 13.6S 113.8E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   231200Z --- 14.4S 112.6E
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
                            055 NM SOUTHEAST QUADRANT
                            055 NM SOUTHWEST QUADRANT
                            045 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 235 DEG/ 06 KTS
    ---
   24 HRS, VALID AT:
   240000Z --- 15.1S 111.5E
   MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   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 - 060 NM NORTHEAST QUADRANT
                            065 NM SOUTHEAST QUADRANT
                            065 NM SOUTHWEST QUADRANT
                            050 NM NORTHWEST QUADRANT
   VECTOR TO 36 HR POSIT: 240 DEG/ 05 KTS
    ---
   36 HRS, VALID AT:
   241200Z --- 15.6S 110.5E
   MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   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 - 060 NM NORTHEAST QUADRANT
                            065 NM SOUTHEAST QUADRANT
                            065 NM SOUTHWEST QUADRANT
                            050 NM NORTHWEST QUADRANT
   VECTOR TO 48 HR POSIT: 250 DEG/ 07 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   250000Z --- 16.0S 109.2E
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
                            055 NM SOUTHEAST QUADRANT
                            055 NM SOUTHWEST QUADRANT
                            045 NM NORTHWEST QUADRANT
   VECTOR TO 72 HR POSIT: 260 DEG/ 06 KTS
    ---
   72 HRS, VALID AT:
   260000Z --- 16.3S 106.9E
   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 - 040 NM NORTHEAST QUADRANT
                            050 NM SOUTHEAST QUADRANT
                            050 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   VECTOR TO 96 HR POSIT: 265 DEG/ 05 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:
   270000Z --- 16.4S 104.8E
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
230300Z POSITION NEAR 13.8S 113.5E.
TROPICAL CYCLONE (TC) 24S (SEAN), LOCATED APPROXIMATELY 510 NM NORTH
OF LEARMONTH, AUSTRALIA, HAS TRACKED WEST-SOUTHWESTWARD AT 07 KNOTS
OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY SHOWS
INCREASED DEEP CONVECTION OVER THE LOW LEVEL CIRCULATION CENTER. A
222159 TRMM 85H AND A 222318 SSMIS 91H MICROWAVE IMAGES INDICATE
CONVECTIVE BANDING WRAPPING IN FROM THE SOUTH AND EAST OF THE SYSTEM
INTO A WELL-DEFINED LLCC. CURRENT INTENSITY IS BASED ON DVORAK
ESTIMATES OF 45 KNOTS FROM PGTW, APRF, AND KNES. UPPER LEVEL
ANALYSIS INDICATES THAT TC 24S IS TRACKING WEST-SOUTHWESTWARD ALONG
THE NORTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR). CURRENTLY
TC SEAN REMAINS IN A FAVORABLE ENVIRONMENT WITH ENHANCED POLEWARD
OUTFLOW AHEAD OF A MIDLATITUDE TROUGH AND LOW TO MODERATE VERTICAL
WIND SHEAR (VWS). NEAR TAU 36, TC 24S IS EXPECTED TO WEAKEN AS IT
ENCOUNTERS INCREASED VWS (20 TO 30 KTS). TC SEAN IS FORECAST TO
DISSIPATE AS A SIGNIFICANT TROPICAL CYCLONE BY TAU 96, WHICH IS A
CHANGE FROM THE PREVIOUS WARNING. NUMERICAL MODEL GUIDANCE IS IN
GOOD AGREEMENT WITH THIS FORECAST WITH THE EXCEPTION OF WBAR, WHICH
ERRONEOUSLY RECURVES THE SYSTEM TO THE SOUTHEAST. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 230000Z IS 14 FEET.
NEXT WARNINGS AT 231500Z AND 240300Z.//
=========================================================================
WTXS31 PGTW 20100423 15:00z
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE 24S (SEAN) WARNING NR 003//
RMKS/
1. TROPICAL CYCLONE 24S (SEAN) WARNING NR 003
   01 ACTIVE TROPICAL CYCLONE IN SOUTHIO
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   231200Z --- NEAR 14.3S 113.6E
     MOVEMENT PAST SIX HOURS - 215 DEGREES AT 04 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 - 045 NM NORTHEAST QUADRANT
                            050 NM SOUTHEAST QUADRANT
                            050 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   REPEAT POSIT: 14.3S 113.6E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   240000Z --- 14.9S 112.6E
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
                            055 NM SOUTHEAST QUADRANT
                            055 NM SOUTHWEST QUADRANT
                            045 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 240 DEG/ 05 KTS
    ---
   24 HRS, VALID AT:
   241200Z --- 15.4S 111.6E
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 055 NM NORTHEAST QUADRANT
                            060 NM SOUTHEAST QUADRANT
                            060 NM SOUTHWEST QUADRANT
                            050 NM NORTHWEST QUADRANT
   VECTOR TO 36 HR POSIT: 245 DEG/ 05 KTS
    ---
   36 HRS, VALID AT:
   250000Z --- 15.8S 110.7E
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
                            055 NM SOUTHEAST QUADRANT
                            055 NM SOUTHWEST QUADRANT
                            045 NM NORTHWEST QUADRANT
   VECTOR TO 48 HR POSIT: 255 DEG/ 05 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   251200Z --- 16.1S 109.6E
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
                            055 NM SOUTHEAST QUADRANT
                            055 NM SOUTHWEST QUADRANT
                            045 NM NORTHWEST QUADRANT
   VECTOR TO 72 HR POSIT: 265 DEG/ 08 KTS
    ---
   72 HRS, VALID AT:
   261200Z --- 16.5S 106.1E
   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
                            050 NM SOUTHEAST QUADRANT
                            050 NM SOUTHWEST QUADRANT
                            045 NM NORTHWEST QUADRANT
   VECTOR TO 96 HR POSIT: 265 DEG/ 14 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:
   271200Z --- 16.7S 100.1E
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
231500Z POSITION NEAR 14.4S 113.3E.
TROPICAL CYCLONE (TC) 24S (SEAN), LOCATED APPROXIMATELY 475 NM NORTH
OF LEARMONTH, AUSTRALIA, HAS TRACKED SOUTHWESTWARD AT 04 KNOTS
OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY AND A
231155Z SSMIS MICROWAVE IMAGE SHOW CONVECTIVE BANDING CONTINUING TO
WRAP INTO THE LOW LEVEL CIRCULATION CENTER (LLCC) FROM THE SOUTH AND
EAST. UPPER LEVEL ANALYSIS INDICATES TC 24S IS LOCATED WEST OF AN
UPPER LEVEL ANTICYCLONE SUPPORTING LOW TO MODERATE VERTICAL WIND
SHEAR (VWS) AND A MID-LATITUDE, UPPER LEVEL TROUGH IS ALLOWING
ENHANCED POLEWARD OUTFLOW. TC SEAN IS CURRENTLY TRACKING ALONG THE
NORTHWESTERN PERIPHERY OF A SUBTROPICAL STEERING RIDGE AND WILL TURN
WESTWARD AS THE RIDGE BUILDS IN WITH THE PASSING OF THE UPPER LEVEL,
MID-LATITUDE TROUGH. INTENSITIES ARE FORECAST TO INCREASE IN THE
NEXT 12 TO 24 HOURS AS VWS REMAINS LOW WITH GOOD OUTFLOW. HOWEVER,
TC SEAN WILL BEGIN TO ENCOUNTER INCREASED VWS BY TAU 36, BEGIN TO
WEAKEN, AND DISSIPATE AS A SIGNIFICANT TROPICAL CYCLONE BY TAU 96.
NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT WITH THIS FORECAST
WITH THE EXCEPTION OF WBAR, WHICH ERRONEOUSLY RECURVES THE SYSTEM TO
THE SOUTHEAST. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 231200Z IS 16 FEET.
NEXT WARNINGS AT 240300Z AND 241500Z.//
=========================================================================
WTXS31 PGTW 20100424 03:00z
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE 24S (SEAN) WARNING NR 004//
RMKS/
1. TROPICAL CYCLONE 24S (SEAN) 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:
   240000Z --- NEAR 16.1S 113.1E
     MOVEMENT PAST SIX HOURS - 185 DEGREES AT 08 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 - 020 NM NORTHEAST QUADRANT
                            025 NM SOUTHEAST QUADRANT
                            025 NM SOUTHWEST QUADRANT
                            020 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 055 NM NORTHEAST QUADRANT
                            060 NM SOUTHEAST QUADRANT
                            055 NM SOUTHWEST QUADRANT
                            045 NM NORTHWEST QUADRANT
   REPEAT POSIT: 16.1S 113.1E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   241200Z --- 17.2S 112.6E
   MAX SUSTAINED WINDS - 055 KT, GUSTS 070 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 - 060 NM NORTHEAST QUADRANT
                            070 NM SOUTHEAST QUADRANT
                            060 NM SOUTHWEST QUADRANT
                            055 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 235 DEG/ 06 KTS
    ---
   24 HRS, VALID AT:
   250000Z --- 17.9S 111.6E
   MAX SUSTAINED WINDS - 055 KT, GUSTS 070 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 - 060 NM NORTHEAST QUADRANT
                            070 NM SOUTHEAST QUADRANT
                            060 NM SOUTHWEST QUADRANT
                            055 NM NORTHWEST QUADRANT
   VECTOR TO 36 HR POSIT: 255 DEG/ 07 KTS
    ---
   36 HRS, VALID AT:
   251200Z --- 18.2S 110.2E
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
                            060 NM SOUTHEAST QUADRANT
                            055 NM SOUTHWEST QUADRANT
                            045 NM NORTHWEST QUADRANT
   VECTOR TO 48 HR POSIT: 270 DEG/ 08 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   260000Z --- 18.2S 108.5E
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 045 NM NORTHEAST QUADRANT
                            050 NM SOUTHEAST QUADRANT
                            050 NM SOUTHWEST QUADRANT
                            045 NM NORTHWEST QUADRANT
   VECTOR TO 72 HR POSIT: 275 DEG/ 11 KTS
    ---
   72 HRS, VALID AT:
   270000Z --- 17.7S 104.1E
   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 - 040 NM NORTHEAST QUADRANT
                            045 NM SOUTHEAST QUADRANT
                            045 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   VECTOR TO 96 HR POSIT: 280 DEG/ 15 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:
   280000Z --- 16.6S 98.0E
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
240300Z POSITION NEAR 16.4S 113.0E.
TROPICAL CYCLONE (TC) 24S (SEAN), LOCATED APPROXIMATELY 370 NM NORTH
OF LEARMONTH, AUSTRALIA, HAS TRACKED SOUTHWARD AT 08 KNOTS OVER THE
PAST SIX HOURS. OVER THE PAST 12 HOURS, TC SEAN HAS TRACKED
GENERALLY SOUTHWARD ALONG THE WESTERN PERIPHERY OF THE LOW- TO MID-
LEVEL SUBTROPICAL STEERING RIDGE AND INTENSIFIED BY 10 KNOTS DUE TO
ENHANCED POLEWARD OUTFLOW CAUSED BY THE PASSING MID-LATITUDE TROUGH.
THE 240000Z POSITION IS BASED ON A 232306Z SSMIS MICROWAVE IMAGE
WHILE THE CURRENT INTENSITY OF 55 KNOTS IS SUPPORTED BY DVORAK
ESTIMATES FROM PGTW AND KNES. CURRENTLY, ANIMATED MULTISPECTRAL
SATELLITE IMAGERY SHOWS EVIDENCE OF UNFAVORABLE NORTHWESTERLY
VERTICAL WIND SHEAR ASSOCIATED WITH THE PASSING TROUGH. ACCORDINGLY,
TC SEAN IS NOT EXPECTED TO FURTHER INTENSIFY THROUGHOUT THE FORECAST
PERIOD. AS FOR TRACK, THE CYCLONE WILL START TO TURN MORE WESTWARD
OVER THE NEXT 24 HOURS AS THE MID-LATITUDE TROUGH PUSHES EASTWARD
AND A COMBINATION OF A WESTWARD PUSHING RIDGE FINGER AND A BUILDING
RIDGE LOCATED TO THE WEST SERVE TO GUIDE THE SYSTEM. WHILE TC SEAN
TRACKS WESTWARD ALONG THE EQUATORWARD SIDE OF THE LOW- TO MID-LEVEL
RIDGE, THE SYSTEM WILL STEADILY WEAKEN AS IT MOVES OVER LESS
FAVORABLE OCEAN HEAT CONTENT VALUES, LOSES POLEWARD OUTFLOW, AND
SUCCUMBS TO INCREASING VERTICAL WIND SHEAR. AFTER TAU 72, THE
CYCLONE SHOULD DISSIPATE AS A SIGNIFICANT TROPICAL CYCLONE AND START
TO DRIFT MORE NORTHWESTWARD WITH THE LOW LEVEL FLOW. ALL JTWC
CONSENSUS MEMBERS, WITH THE EXCEPTION OF WBAR, CONTINUE TO AGREE
WITH THE WESTWARD TURN. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 240000Z
IS 16 FEET. NEXT WARNINGS AT 241500Z AND 250300Z.//
=========================================================================
WTXS31 PGTW 20100424 15:00z
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE 24S (SEAN) WARNING NR 005//
RMKS/
1. TROPICAL CYCLONE 24S (SEAN) 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:
   241200Z --- NEAR 17.4S 112.4E
     MOVEMENT PAST SIX HOURS - 200 DEGREES AT 08 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 - 055 NM NORTHEAST QUADRANT
                            060 NM SOUTHEAST QUADRANT
                            055 NM SOUTHWEST QUADRANT
                            045 NM NORTHWEST QUADRANT
   REPEAT POSIT: 17.4S 112.4E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   250000Z --- 18.4S 111.4E
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 055 NM NORTHEAST QUADRANT
                            060 NM SOUTHEAST QUADRANT
                            055 NM SOUTHWEST QUADRANT
                            045 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 250 DEG/ 06 KTS
    ---
   24 HRS, VALID AT:
   251200Z --- 18.8S 110.1E
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
                            055 NM SOUTHEAST QUADRANT
                            050 NM SOUTHWEST QUADRANT
                            045 NM NORTHWEST QUADRANT
   VECTOR TO 36 HR POSIT: 265 DEG/ 08 KTS
    ---
   36 HRS, VALID AT:
   260000Z --- 18.9S 108.4E
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
                            055 NM SOUTHEAST QUADRANT
                            050 NM SOUTHWEST QUADRANT
                            045 NM NORTHWEST QUADRANT
   VECTOR TO 48 HR POSIT: 265 DEG/ 11 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   261200Z --- 19.1S 106.0E
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   VECTOR TO 72 HR POSIT: 275 DEG/ 10 KTS
    ---
   72 HRS, VALID AT:
   271200Z --- 18.8S 101.8E
   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 96 HR POSIT: 280 DEG/ 11 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:
   281200Z --- 18.1S 97.4E
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
241500Z POSITION NEAR 17.7S 112.1E.
TROPICAL CYCLONE (TC) 24S (SEAN), LOCATED APPROXIMATELY 300 NM NORTH-
NORTHWEST OF LEARMONTH, AUSTRALIA, HAS TRACKED SOUTH-SOUTHWESTWARD AT
08 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY
SHOWS DEEP CONVECTION HAS BEEN PERSISTING OVER THE LOW LEVEL CIRCULA-
TION CENTER (LLCC) AS VERTICAL WIND SHEAR (VWS) HAS BEEN SLOWLY
INCREASING OVER THE PAST 12 HOURS. A 241141Z SSMIS PASS SUPPORTED THE
CURRENT POSITION OF TC 24S. UPPER LEVEL ANALYSIS INDICATES THAT TC
24S IS POLEWARD OF A SUBTROPICAL RIDGE (STR) AXIS, WHICH IS CREATING
STRONG NORTHWESTERLY FLOW OVER TC 24S, LEADING TO HIGH VWS (30 KNOTS)
OVER THE LLCC. THE CURRENT FORECAST IS BASED ON CONTINUED VWS VALUES
LEADING TO A SEPARATION OF THE DEEP CONVECTION FROM THE LOW LEVEL.
THE CONVECTION WILL LIKELY CONTINUE TO TRACK TO THE SOUTHEAST AS THE
LLCC SWITCHES TO A LOWER LEVEL STEERING ENVIRONMENT. SURFACE RIDGING
TO THE SOUTHWEST OF TC 24S WILL CAUSE A WESTWARD SHIFT IN THE TRACK
WITHIN THE NEXT 24 HOURS, AND WILL CONTINUE THROUGH TAU 96. THE FAV-
ORABLE SURFACE CONDITIONS WILL BEGIN TO DIMINISH AND IN ASSOCIATION
WITH THE HIGH VWS VALUES WILL CAUSE TC 24S TO BEGIN DISSIPATING BY
TAU 72, WITH COMPLETE DISSIPATION BY TAU 96. MAXIMUM SIGNIFICANT WAVE
HEIGHT AT 241200Z IS 15 FEET. NEXT WARNINGS AT 250300Z AND 251500Z.//
=========================================================================
WTXS31 PGTW 20100425 03:00z
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE 24S (SEAN) WARNING NR 006//
RMKS/
1. TROPICAL CYCLONE 24S (SEAN) 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:
   250000Z --- NEAR 17.5S 111.3E
     MOVEMENT PAST SIX HOURS - 260 DEGREES AT 08 KTS
     POSITION ACCURATE TO WITHIN 025 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: 17.5S 111.3E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   251200Z --- 17.5S 109.6E
   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: 275 DEG/ 10 KTS
    ---
   24 HRS, VALID AT:
   260000Z --- 17.3S 107.5E
   MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
250300Z POSITION NEAR 17.5S 110.9E.
TROPICAL CYCLONE (TC) 24S (SEAN), LOCATED APPROXIMATELY 325 NM NORTH-
NORTHWEST OF LEARMONTH, AUSTRALIA, HAS TRACKED WESTWARD AT 08 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
REVEALS A FULLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) WITH
DISSIPATING CONVECTION SHEARED TO THE SOUTHEAST. OVER THE PAST 12
HOURS, TC SEAN HAS WEAKENED BY 15 KNOTS DUE TO UNFAVORABLE VERTICAL
WIND SHEAR ASSOCIATED WITH A MID-LATITUDE TROUGH WEST OF THE LLCC.
THE CURRENT INTENSITY OF 35 KNOTS IS BASED ON DECLINING DVORAK
ESTIMATES OF 1.5/2.5 FROM PGTW AND KNES AND IS SUPPORTED BY A 13-
HOUR OLD ASCAT PASS (241350Z) WHICH DEPICTED A MAXIMUM OF 35-KNOT
WINDS. AS THE SYSTEM HAS WEAKENED, IT HAS SHIFTED TO A SHALLOW
STEERING LEVEL AND IS EXPECTED TO CONTINUE TRACKING WESTWARD WITH
THE LOW LEVEL FLOW OVER THE NEXT DAY WHILE DISSIPATING AS A
SIGNIFICANT TROPICAL CYCLONE. 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 250000Z IS 17 FEET.//

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


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Document: tropical_cyclone_sean_jtwc_advisories.htm Updated: 2 May 2017