Tropical Cyclones
[Index] | Tropical Cyclone 201120 : JTWC Advisories |
Season 2010-2011 Summaries (Operational Data): [AU] [SIO] [SPAC] [SH] | |
---> Tropical Cyclone 201120 Track Map and Data |
WTXS21 PGTW 20110401 16:30z MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/TROPICAL CYCLONE FORMATION ALERT// RMKS/ 1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN 130 NM EITHER SIDE OF A LINE FROM 12.9S 129.2E TO 14.8S 125.3E 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 IMAGERY, SYNOPTIC DATA AND RADAR DATA AT 011600Z INDICATE THAT A CIRCULATION CENTER IS LOCATED NEAR 13.2S 128.9E. THE SYSTEM IS MOVING SOUTHWESTWARD AT 04 KNOTS. 2. REMARKS: ANIMATED INFRARED SATELLITE AND RADAR IMAGERY DEPICT A CONSOLIDATING LOW-LEVEL CIRCULATION CENTER (LLCC) WITH IMPROVED CONVECTIVE BANDING WRAPPING INTO A DEFINED CENTER. ANIMATED WATER VAPOR IMAGERY INDICATES THAT THE LLCC IS LOCATED JUST EQUATORWARD OF THE RIDGE AXIS AND IS UNDER DIFFLUENT EASTERLY FLOW WITH MODERATE VERTICAL WIND SHEAR (15-20 KNOTS). HOWEVER, POLEWARD OUTFLOW IS GOOD, ENHANCED BY UPPER-LEVEL WESTERLIES OVER AUSTRALIA, WHILE EQUATORWARD OUTFLOW IS RESTRICTED OVER THE NORTHEAST QUADRANT. A 011020Z SSMIS IMAGE ALSO SUPPORTS IMPROVED ORGANIZATION WITH MULTIPLE CONVECTIVE BANDS WRAPPING INTO THE CENTER. A 011232Z ASCAT IMAGE SHOWS 25-30 KNOT UNFLAGGED WINDS OVER THE WESTERN QUADRANT. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25 TO 30 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1000 MB. THE SYSTEM IS EXPECTED TO TRACK OVER OR JUST TO THE NORTH OF THE AUSTRALIAN COAST WITH VERTICAL WIND SHEAR EXPECTED TO DECREASE IN THE NEXT 24 HOURS, THEREFORE, 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 021630Z.// ========================================================================= WTXS31 PGTW 20110402 03:00z MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/TROPICAL CYCLONE 20S (TWENTY) WARNING NR 001// REF/A/MSG/NAVMARFCSTCEN PEARL HARBOR HI/011621ZAPR2011// AMPN/REF A IS A TROPICAL CYCLONE FORMATION ALERT.// RMKS/ 1. TROPICAL CYCLONE 20S (TWENTY) 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: 020000Z --- NEAR 13.5S 127.6E MOVEMENT PAST SIX HOURS - 250 DEGREES AT 08 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY A COMBINATION OF SATELLITE AND RADAR PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY REPEAT POSIT: 13.5S 127.6E --- FORECASTS: 12 HRS, VALID AT: 021200Z --- 14.2S 126.1E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 24 HR POSIT: 245 DEG/ 08 KTS --- 24 HRS, VALID AT: 030000Z --- 14.9S 124.6E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 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 36 HR POSIT: 245 DEG/ 08 KTS --- 36 HRS, VALID AT: 031200Z --- 15.6S 123.1E 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 48 HR POSIT: 250 DEG/ 09 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 040000Z --- 16.3S 121.3E MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT WIND RADII VALID OVER OPEN WATER ONLY 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 - 050 NM NORTHEAST QUADRANT 055 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 240 DEG/ 07 KTS --- 72 HRS, VALID AT: 050000Z --- 17.8S 118.8E MAX SUSTAINED WINDS - 085 KT, GUSTS 105 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 - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT 065 NM SOUTHEAST QUADRANT 065 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 225 DEG/ 06 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: 060000Z --- 19.4S 117.0E MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 120 HR POSIT: 195 DEG/ 06 KTS --- 120 HRS, VALID AT: 070000Z --- 21.8S 116.4E MAX SUSTAINED WINDS - 075 KT, GUSTS 090 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING EXTRATROPICAL --- REMARKS: 020300Z POSITION NEAR 13.7S 127.2E. TROPICAL CYCLONE (TC) 20S, LOCATED APPROXIMATELY 660 NM NORTHEAST OF PORT HEDLAND, AUSTRALIA, HAS TRACKED WEST-SOUTHWESTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE AND RADAR IMAGERY DEPICT A CONSOLIDATING LOW-LEVEL CIRCULATION CENTER (LLCC) WITH IMPROVED CONVECTIVE BANDING WRAPPING INTO A DEFINED CENTER. ANIMATED WATER VAPOR IMAGERY INDICATES THAT THE LLCC IS LOCATED JUST EQUATORWARD OF THE RIDGE AXIS AND IS UNDER DIFFLUENT EASTERLY FLOW WITH MODERATE VERTICAL WIND SHEAR (15-20 KNOTS). HOWEVER, POLEWARD OUTFLOW IS GOOD, ENHANCED BY UPPER-LEVEL WESTERLIES OVER AUSTRALIA, WHILE EQUATORWARD OUTFLOW IS RESTRICTED OVER THE NORTHEAST QUADRANT. A 012131Z SSMIS 37 GHZ IMAGE DEPICTS IMPROVED LOW-LEVEL CONVECTIVE BANDING WRAPPING TIGHTLY INTO A WELL-DEFINED LLCC. AN EARLIER ASCAT IMAGE AT 011232Z INDICATED 25-30 KNOT UNFLAGGED WINDS OVER THE WESTERN QUADRANT AND BASED ON RECENT IMAGERY THE SYSTEM HAS CONTINUED TO CONSOLIDATE. THE CURRENT POSITION IS BASED ON THE SSMIS IMAGE AND RADAR IMAGERY WITH GOOD CONFIDENCE. THE CURRENT INTENSITY IS BASED ON A DVORAK ESTIMATE OF 35 KNOTS FROM PGTW. TC 20S IS FORECAST TO TRACK WESTWARD THROUGH TAU 72 UNDER THE STEERING INFLUENCE OF A DEEP SUBTROPICAL RIDGE POSITIONED OVER AUSTRALIA. THE SYSTEM SHOULD RE-CURVE AHEAD OF A DEEP MIDLATITUDE SHORT-WAVE TROUGH WHICH IS FORECAST TO DEEPEN OVER WESTERN AUSTRALIA AFTER TAU 72. DYNAMIC MODEL GUIDANCE IS IN TIGHT AGREEMENT WITH THE EXCEPTION OF NOGAPS, WHICH ERRONEOUSLY TRACKS THE SYSTEM WESTWARD THROUGH THE PERIOD DESPITE A SIMILAR DEPICTION OF THE DEEPENING TROUGH. THIS FORECAST IS POSITIONED CLOSE TO THE MODEL CONSENSUS THROUGH TAU 72 BUT IS POLEWARD IN THE EXTENDED TAUS DUE TO THE PROBLEM WITH THE NOGAPS TRACKER. TC 20S IS FORECAST TO INTENSIFY AT A SLOW RATE THROUGH TAU 36 DUE TO MODERATE VERTICAL WIND SHEAR AND LAND INTERACTION. AFTERWARDS, THE SYSTEM SHOULD INTENSIFY AT A 25-30 KNOT RATE PER DAY UNTIL IT MAKES LANDFALL NEAR TAU 120. THIS WARNING SUPERSEDES AND CANCELS REF A, NAVMARFCSTCEN 011621Z APR 11 TROPICAL CYCLONE FORMATION ALERT (WTXS21 PGTW 011630). MAXIMUM SIGNIFICANT WAVE HEIGHT AT 020000Z IS 10 FEET. NEXT WARNINGS AT 021500Z AND 030300Z.// ========================================================================= WTXS31 PGTW 20110402 15:00z MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/TROPICAL CYCLONE 20S (TWENTY) WARNING NR 002// RMKS/ 1. TROPICAL CYCLONE 20S (TWENTY) 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: 021200Z --- NEAR 14.1S 126.8E MOVEMENT PAST SIX HOURS - 225 DEGREES AT 04 KTS POSITION ACCURATE TO WITHIN 030 NM POSITION BASED ON CENTER LOCATED BY A COMBINATION OF SATELLITE AND RADAR PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY REPEAT POSIT: 14.1S 126.8E --- FORECASTS: 12 HRS, VALID AT: 030000Z --- 14.8S 125.4E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 24 HR POSIT: 245 DEG/ 08 KTS --- 24 HRS, VALID AT: 031200Z --- 15.5S 123.9E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 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 36 HR POSIT: 250 DEG/ 07 KTS --- 36 HRS, VALID AT: 040000Z --- 16.0S 122.5E 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 48 HR POSIT: 250 DEG/ 08 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 041200Z --- 16.5S 121.0E MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT WIND RADII VALID OVER OPEN WATER ONLY 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 - 050 NM NORTHEAST QUADRANT 055 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 250 DEG/ 07 KTS --- 72 HRS, VALID AT: 051200Z --- 17.5S 118.2E MAX SUSTAINED WINDS - 085 KT, GUSTS 105 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 - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT 065 NM SOUTHEAST QUADRANT 065 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 245 DEG/ 06 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: 061200Z --- 18.5S 115.8E MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 120 HR POSIT: 210 DEG/ 04 KTS --- 120 HRS, VALID AT: 071200Z --- 19.9S 114.9E MAX SUSTAINED WINDS - 075 KT, GUSTS 090 KT WIND RADII VALID OVER OPEN WATER ONLY --- REMARKS: 021500Z POSITION NEAR 14.3S 126.4E. TROPICAL CYCLONE (TC) 20S (TWENTY), LOCATED APPROXIMATELY 875 NM EAST-NORTHEAST OF LEARMONTH, AUSTRALIA, HAS TRACKED SOUTHWESTWARD AT 04 KNOTS OVER THE PAST SIX HOURS. ANIMATED WATER VAPOR IMAGERY SHOWS CENTRAL CONVECTION ASSOCIATED WITH THE SYSTEM HAS REDUCED AS THE LOW LEVEL CIRCULATION CENTER (LLCC) MOVED ONSHORE NEAR KALUMBURU. HOWEVER, CONVECTIVE BANDS REMAIN INTACT AND TIGHTLY WRAPPED INTO THE LLCC AS EVIDENCED ON RADAR LOOP FROM WYNDHAM. THE INITIAL POSITION IS BASED ON THE ABOVE RADAR ANIMATION WITH A FAIR DEGREE OF CONFIDENCE. THE INITIAL INTENSITY IS BASED ON DVORAK ESTIMATE OF 35 KNOTS FROM KNES, PGTW, AND APRF. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS JUST TO THE NORTH OF A RIDGE AXIS IN AN AREA OF LIGHT TO MODERATE VERTICAL WIND SHEAR. A ROBUST OUTFLOW CHANNEL EXISTS POLEWARD OF THE RIDGE AXIS. TC 20S IS EXPECTED TO STRADDLE THE KIMBERLY COAST BEFORE IT RE-ENTERS THE WARM WATERS OF THE SOUTHERN INDIAN OCEAN BY TAU 24. FAVORABLE ENVIRONMENTAL CONDITIONS WILL FUEL A SLIGHTLY ABOVE NORMAL INTENSIFICATION, PEAKING AT 90 KTS AT TAU 96 BEFORE IT BEGINS TO RECURVE POLEWARD TOWARDS LEARMONTH WITH THE APPROACH OF A MID-LATITUDE TROUGH FROM THE SOUTHWEST. THE AVAILABLE NUMERIC GUIDANCE IS IN OVERALL GOOD AGREEMENT WITH THIS TRACK WITH THE EXCEPTION OF NOGAPS THAT FAVORS A WESTWARD MOVEMENT AFTER TAU 48, INDICATING MINIMAL IMPACT FROM THE MID-LATITUDE TROUGH. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 021200Z IS 8 FEET. NEXT WARNINGS AT 030300Z AND 031500Z.// ========================================================================= WTXS31 PGTW 20110403 03:00z MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/TROPICAL CYCLONE 20S (TWENTY) WARNING NR 003// RMKS/ 1. TROPICAL CYCLONE 20S (TWENTY) 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: 030000Z --- NEAR 15.2S 125.1E MOVEMENT PAST SIX HOURS - 230 DEGREES AT 09 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY A COMBINATION OF SATELLITE AND RADAR PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY REPEAT POSIT: 15.2S 125.1E --- FORECASTS: 12 HRS, VALID AT: 031200Z --- 15.8S 124.0E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 24 HR POSIT: 240 DEG/ 06 KTS --- 24 HRS, VALID AT: 040000Z --- 16.4S 122.8E 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 36 HR POSIT: 250 DEG/ 08 KTS --- 36 HRS, VALID AT: 041200Z --- 16.9S 121.3E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 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 48 HR POSIT: 255 DEG/ 08 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 050000Z --- 17.4S 119.6E MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT WIND RADII VALID OVER OPEN WATER ONLY 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 - 050 NM NORTHEAST QUADRANT 055 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 245 DEG/ 07 KTS --- 72 HRS, VALID AT: 060000Z --- 18.5S 116.8E MAX SUSTAINED WINDS - 075 KT, GUSTS 090 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 - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT 065 NM SOUTHEAST QUADRANT 065 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 220 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: 070000Z --- 20.1S 115.3E MAX SUSTAINED WINDS - 080 KT, GUSTS 100 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 120 HR POSIT: 190 DEG/ 05 KTS --- 120 HRS, VALID AT: 080000Z --- 22.1S 115.0E MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING EXTRATROPICAL --- REMARKS: 030300Z POSITION NEAR 15.4S 124.8E. TROPICAL CYCLONE (TC) 20S, LOCATED APPROXIMATELY 760 NM EAST- NORTHEAST OF LEARMONTH, AUSTRALIA, HAS TRACKED SOUTHWESTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS RAPIDLY DECAYING DEEP CONVECTION DUE TO LAND INTERACTION AS TC 20S CONTINUES TO TRACK ALONG THE KIMBERLY COAST. ANIMATED WATER VAPOR IMAGERY INDICATES THAT THE LLCC HAS TRACKED UNDER THE UPPER-LEVEL RIDGE AXIS, THEREFORE, VERTICAL WIND SHEAR HAS DECREASED AND OUTFLOW HAS IMPROVED. RECENT MICROWAVE IMAGERY TO INCLUDE A 022128Z CORIOLIS IMAGE AND A 022341Z SSMIS IMAGE CONTINUE TO SHOW OVERALL TIGHTLY-CURVED LOW-LEVEL CONVECTIVE BANDING WITH FRAGMENTED DEEP CONVECTIVE BANDING OVER THE EAST AND SOUTHWEST QUADRANTS. THE TOTAL PRECIPITABLE WATER PRODUCT INDICATES A DEEP MOISTURE ENVELOPE WITH SOME DRY AIR OVER THE WEST AND NORTHWEST PERIPHERY OF THE SYSTEM. THE CURRENT POSITION IS BASED ON RADAR IMAGERY AND THE MSI WITH FAIR CONFIDENCE. THE CURRENT INTENSITY IS BASED ON PERSISTENCE DUE TO THE LACK OF DVORAK ESTIMATES OVER LAND. TC 20S IS FORECAST TO TRACK WESTWARD THROUGH TAU 72 UNDER THE STEERING INFLUENCE OF A DEEP SUBTROPICAL RIDGE POSITIONED OVER AUSTRALIA. DYNAMIC MODEL GUIDANCE IS IN TIGHT AGREEMENT SO THIS FORECAST IS POSITIONED CLOSE TO THE MODEL CONSENSUS. THE DYNAMIC MODELS, HOWEVER, INDICATE A WEAK SYSTEM WITH PEAK INTENSITIES LESS THAN 50 KNOTS. NOGAPS AND GFDN PEAK TC 20S AT ABOUT 40 KNOTS. THIS LACK OF INTENSIFICATION IN THE MODELS IS LIKELY DUE TO THE FLAT INTENSIFICATION TREND OVER THE PAST DAY AS TC 20S TRACKED OVER LAND AND POSSIBLY DUE TO FORECASTED DRY AIR ENTRAINMENT HINDERING SIGNIFICANT DEVELOPMENT. THE DYNAMIC MODELS FURTHER WEAKEN THE SYSTEM AFTER TAU 72 AND TRACK IT UNDER A STRONG LOW-LEVEL RIDGE EXPECTED TO BUILD IN AFTER A DEEP MIDLATITUDE SHORTWAVE TROUGH AND FRONT MOVE INTO WESTERN AUSTRALIA. THIS FORECAST REMAINS CONSISTENT WITH PREVIOUS FORECASTS AND IS BASED ON THE SYSTEM INTENSIFYING TO A PEAK INTENSITY NEAR 75-80 KNOTS AS IT TRACKS OVER WARM SST WITH FAVORABLE CONDITIONS PREVAILING AFTER TAU 24. THEREFORE, THE SYSTEM IS EXPECTED TO RE-CURVE AHEAD OF A DEEP MIDLATITUDE SHORT-WAVE TROUGH AFTER TAU 72. AT THIS TIME, THE WEAKENING/DISSIPATIOJN SCENARIO IS DEEMED UNLIKELY. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 030000Z IS 8 FEET. NEXT WARNINGS AT 031500Z AND 040300Z.// ========================================================================= WTXS31 PGTW 20110403 15:00z MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/TROPICAL CYCLONE 20S (TWENTY) WARNING NR 004// RMKS/ 1. TROPICAL CYCLONE 20S (TWENTY) 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: 031200Z --- NEAR 15.5S 124.4E MOVEMENT PAST SIX HOURS - 240 DEGREES AT 06 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY A COMBINATION OF SATELLITE AND RADAR PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 025 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT REPEAT POSIT: 15.5S 124.4E --- FORECASTS: 12 HRS, VALID AT: 040000Z --- 16.0S 123.4E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 025 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 260 DEG/ 06 KTS --- 24 HRS, VALID AT: 041200Z --- 16.2S 122.2E 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 36 HR POSIT: 255 DEG/ 07 KTS --- 36 HRS, VALID AT: 050000Z --- 16.6S 120.7E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 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 48 HR POSIT: 250 DEG/ 08 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 051200Z --- 17.2S 119.1E MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT WIND RADII VALID OVER OPEN WATER ONLY 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 - 050 NM NORTHEAST QUADRANT 055 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 235 DEG/ 07 KTS --- 72 HRS, VALID AT: 061200Z --- 18.7S 116.6E MAX SUSTAINED WINDS - 075 KT, GUSTS 090 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 - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT 065 NM SOUTHEAST QUADRANT 065 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 210 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: 071200Z --- 20.4S 115.6E MAX SUSTAINED WINDS - 080 KT, GUSTS 100 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 120 HR POSIT: 185 DEG/ 06 KTS --- 120 HRS, VALID AT: 081200Z --- 22.6S 115.3E MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT WIND RADII VALID OVER OPEN WATER ONLY --- REMARKS: 031500Z POSITION NEAR 15.6S 124.1E. TROPICAL CYCLONE (TC) 20S (TWENTY), LOCATED APPROXIMATELY 710 NM EAST-NORTHEAST OF LEARMONTH, AUSTRALIA, HAS TRACKED SOUTHWESTWARD AT 06 KNOTS OVER THE PAST SIX HOURS. ANIMATED WATER VAPOR IMAGERY SHOWS WEAKENED CONVECTIVE BANDING AS THE SYSTEM CONTINUES TO TRACK ALONG THE RUGGED KIMBERLY COAST. THE INITIAL POSITION IS BASED ON A RADAR LOOP FROM WYNDHAM AND FROM A 030955Z SSMI-S MICROWAVE IMAGE WITH GOOD CONFIDENCE. THE INITIAL INTENSITY IS EXTRAPOLATED FROM NEARBY SURFACE OBSERVATIONS. TC 20S IS POISED TO EXIT INTO THE WARM WATERS OF THE SOUTH INDIAN OCEAN. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS JUST UNDERNEATH THE RIDGE AXIS IN AN AREA OF LOW VERTICAL WIND SHEAR AND INCREASING POLEWARD OUTFLOW. THIS IS ALSO EVIDENT ON THE ANIMATED WATER VAPOR IMAGERY. AS TC 20S CONTINUES TO TRACK ALONG THE NORTHWEST PERIPHERY OF THE STEERING SUBTROPICAL RIDGE TO THE SOUTHEAST, IT WILL GRADUALLY INTENSIFY AT A SLIGHTLY HIGHER THAN NORMAL RATE, PEAKING AT 80 KNOTS BEFORE IT BEGINS TO RECURVE TO THE SOUTH NEAR LEARMONTH IN RESPONSE TO A DEEP MID-LATITUDE TROUGH APPROACHING FROM THE SOUTHWEST. THE AVAILABLE NUMERIC GUIDANCE ARE IN GOOD AGREEMENT WITH THIS TRACK FORECAST UP TO TAU 48 WHERE THEY CONTINUE TO TRACK THE SYSTEM WESTWARD. THIS SCENARIO IS BASED ON A SIGNIFICANTLY WEAKENED SYSTEM TRACKING ALONG THE NORTHERN PERIPHERY OF A SHALLOW SUBTROPICAL RIDGE TRAILING BEHIND THE AFOREMENTIONED TROUGH. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 031200Z IS 10 FEET. NEXT WARNINGS AT 040300Z AND 041500Z.// ========================================================================= WTXS31 PGTW 20110404 03:00z MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/TROPICAL CYCLONE 20S (TWENTY) WARNING NR 005// RMKS/ 1. TROPICAL CYCLONE 20S (TWENTY) 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: 040000Z --- NEAR 16.4S 123.5E MOVEMENT PAST SIX HOURS - 250 DEGREES AT 06 KTS POSITION ACCURATE TO WITHIN 060 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT WIND RADII VALID OVER OPEN WATER ONLY REPEAT POSIT: 16.4S 123.5E --- FORECASTS: 12 HRS, VALID AT: 041200Z --- 16.6S 122.5E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 24 HR POSIT: 250 DEG/ 07 KTS --- 24 HRS, VALID AT: 050000Z --- 17.1S 121.2E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 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 36 HR POSIT: 255 DEG/ 07 KTS --- 36 HRS, VALID AT: 051200Z --- 17.5S 119.8E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 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 48 HR POSIT: 245 DEG/ 09 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 060000Z --- 18.3S 118.0E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT 055 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 245 DEG/ 07 KTS --- 72 HRS, VALID AT: 070000Z --- 19.4S 115.5E MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT 065 NM SOUTHEAST QUADRANT 065 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 285 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: 080000Z --- 18.7S 112.5E 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: 300 DEG/ 09 KTS --- 120 HRS, VALID AT: 090000Z --- 16.9S 109.1E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER --- REMARKS: 040300Z POSITION NEAR 16.5S 123.2E. TROPICAL CYCLONE (TC) 20S, LOCATED APPROXIMATELY 640 NM EAST- NORTHEAST OF LEARMONTH, AUSTRALIA, HAS TRACKED WEST-SOUTHWESTWARD AT 06 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A SIGNIFICANTLY WEAKENED, EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH ISOLATED DEEP CONVECTION FLARING OVER THE SOUTHEAST QUADRANT. A 032250Z TRMM 37 GHZ IMAGE SHOWS A WEAK, BUT DISCERNIBLE LLCC JUST OFF THE COAST OF AUSTRALIA. BASED ON THIS IMAGERY, THERE IS FAIR CONFIDENCE IN THE CURRENT POSITION. THE CURRENT INTENSITY OF 25 KNOTS IS BASED PRIMARILY ON NUMEROUS SURFACE OBSERVATIONS WHICH INDICATE SUSTAINED WINDS OF ONLY 15-21 KNOTS NEAR THE CENTER. THE CURRENT FORECAST DEPARTS SIGNIFICANTLY FROM THE PREVIOUS FORECAST DUE TO THE RAPID WEAKENING IN INTENSITY OVER THE PAST 24 HOURS AS THE SYSTEM TRACKED UNEXPECTEDLY SOUTHWESTWARD OVER LAND. ADDITIONALLY, THE TOTAL PRECIPITABLE WATER PRODUCTS AND SOUNDINGS NOW PROVIDE CLEAR EVIDENCE OF THE PRESENCE OF DRY AIR WEST OF THE SYSTEM, WHICH WILL SERVE TO HINDER SIGNIFICANT DEVELOPMENT. TC 20S IS NOW FORECAST TO TRACK WESTWARD UNDER THE STEERING INFLUENCE OF A DEEP SUBTROPICAL RIDGE OVER AUSTRALIA AND WITH A SLIGHT STAIR-STEP WEST-SOUTHWESTWARD NEAR TAU 72 IN RESPONSE TO A MIDLATITUDE TROUGH MOVING INTO WESTERN AUSTRALIA. AFTER TAU 72, THE LOW- TO MID-LEVEL RIDGE IS EXPECTED TO BUILD SOUTH OF THE SYSTEM ALLOWING THE SYSTEM TO TURN WEST-NORTHWESTWARD. THE DECISION TO CHANGE THE FORECAST PHILOSOPHY IS BASED ON A MUCH WEAKER SYSTEM PEAKING AT 45-55 KNOTS, WHICH IS UNLIKELY TO RE-CURVE, AND THE STRONG RIDGING BUILDING BEHIND THE TROUGH. DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT, SUPPORTING THE CURRENT FORECAST. RELIABLE INTENSITY GUIDANCE HAS ALSO COME INTO CLOSER AGREEMENT ESPECIALLY GFDN AND STIPS, WHICH SUPPORT THE INTENSITY FORECAST. TC 20S IS FORECAST TO DISSIPATE BY TAU 120 DUE TO THE INTRUSION OF COOLER, MORE STABLE AIR ASSOCIATED WITH THE STRONG RIDGE. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 040000Z IS 10 FEET. NEXT WARNINGS AT 041500Z AND 050300Z.// ========================================================================= WTXS31 PGTW 20110404 15:00z MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/TROPICAL CYCLONE 20S (TWENTY) WARNING NR 006// RMKS/ 1. TROPICAL CYCLONE 20S (TWENTY) 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: 041200Z --- NEAR 16.3S 122.4E MOVEMENT PAST SIX HOURS - 270 DEGREES AT 05 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 WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER REPEAT POSIT: 16.3S 122.4E --- FORECASTS: 12 HRS, VALID AT: 050000Z --- 16.5S 121.3E MAX SUSTAINED WINDS - 020 KT, GUSTS 030 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER --- REMARKS: 041500Z POSITION NEAR 16.4S 122.1E. TROPICAL CYCLONE (TC) 20S (TWENTY), LOCATED APPROXIMATELY 590 NM NORTHEAST OF LEARMONTH, AUSTRALIA, HAS TRACKED WESTWARD AT 05 KTS OVER THE PAST SIX HOURS. ANIMATED INFRARED IMAGERY SHOWS THE LOW LEVEL CIRCULATION CENTER (LLCC) CONTINUES TO TRACK OVER WATER BUT HAS BECOME BROAD AND DISFIGURED. THE CENTRAL CONVECTION HAS ALL BUT DISSIPATED WITH REMNANT CONVECTION OVER LAND AND DETACHED FROM THE LLCC. THE INITIAL POSITION, BASED ON ANIMATED INFRARED SATELLITE IMAGERY, HAS BEEN DIFFICULT TO PINPOINT. THE INITIAL INTENSITY IS EXTRAPOLATED FROM NEARBY SURFACE OBSERVATIONS AS DVORAK INTENSITY ESTIMATES FROM TRACKING AGENCIES HAVE CEASED DUE TO CLOUD SIGNATURE BEING UNCLASSIFIABLE. TC 20S IS EXPECTED TO REMAIN AS A WEAK DISTURBANCE AND DRIFT WESTWARD ALONG THE NORTHERN PERIPHERY OF THE STEERING RIDGE TO THE SOUTH. 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 041200Z IS 8 FEET.//
Tropical cyclone tracks developed by Michael Bath using operational warnings and advisories.
Document: tropical_cyclone_201120_jtwc_advisories.htm
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