WTIO30 FMEE 170623 RSMC / TROPICAL CYCLONE CENTER / LA REUNION TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN) 0.A WARNING NUMBER: 31/5/20142015 1.A TROPICAL CYCLONE 5 (BANSI) 2.A POSITION 2015/01/17 AT 0600 UTC: WITHIN 20 NM RADIUS OF POINT 23.8 S / 68.7 E (TWENTY THREE DECIMAL EIGHT DEGREES SOUTH AND SIXTY EIGHT DECIMAL SEVEN DEGREES EAST) MOVEMENT : EAST-SOUTH-EAST 10 KT 3.A DVORAK ANALYSIS: 4.5/4.5/W 1.0/12 H 4.A CENTRAL PRESSURE: 956 HPA 5.A MAX AVERAGE WIND SPEED (10 MN): 70 KT RADIUS OF MAXIMUM WINDS (RMW) :41 KM 6.A EXTENSION OF WIND BY QUADRANTS (KM): 28 KT NE: 560 SE: 930 SW: 930 NW: 500 34 KT NE: 350 SE: 440 SW: 540 NW: 280 48 KT NE: 190 SE: 170 SW: 190 NW: 130 64 KT NE: 70 SE: 80 SW: 80 NW: 70 7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1007 HPA / 1700 KM 8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION : DEEP 1.B FORECASTS: 12H: 2015/01/17 18 UTC: 24.3 S / 71.8 E, MAX WIND=060 KT, SEVERE TROPICAL STORM 24H: 2015/01/18 06 UTC: 25.3 S / 75.8 E, MAX WIND=055 KT, POST-TROPICAL DEPRESSION 36H: 2015/01/18 18 UTC: 26.9 S / 81.1 E, MAX WIND=055 KT, POST-TROPICAL DEPRESSION 48H: 2015/01/19 06 UTC: 29.5 S / 85.7 E, MAX WIND=050 KT, POST-TROPICAL DEPRESSION 60H: 2015/01/19 18 UTC: 33.4 S / 89.5 E, MAX WIND=045 KT, POST-TROPICAL DEPRESSION 72H: 2015/01/20 06 UTC: 34.6 S / 93.2 E, MAX WIND=040 KT, EXTRATROPICAL SYSTEM 2.B LONGER-RANGE OUTLOOK : 96H: 2015/01/21 06 UTC: 34.9 S / 98.0 E, MAX WIND=025 KT, LOW 2.C ADDITIONAL INFORMATIONS: T=4.5+ AND CI=4.5+ THE MW IMAGERY (SSMIS 0157Z) SHOWS A WEAKENING OF THE EYEWALL IN THE WESTERN SECTOR, AND THE DEEP CONVECTION SHIFTED EAST OF THE LOW LEVEL CIRCULATION, INDICATING THAT THE SYSTEM BANSI IS BEGINNING TO STRUGGLE AGAINST WESTERLY VERTICAL WINDSHEAR. THE IR SATELLITE PICTURES DEPICT A WARMING OF THE CDO DURING THE PAST 6 HOURS, AND A SLIGHTLY IMPROVING EYE STRUCTURE. DURING THE PAST 6 HOURS, BANSI HAS MOVED EAST-SOUTH-EASTWARD AT 10KT. TODAY AND SUNDAY, BANSI WILL REMAIN ON A EAST-SOUTH-EAST TRACK UNDER THE STEERING FLOW OF THE HIGH PRESSURE IN ITS NORTH-EAST AND ITS NORTH IN THE MID AND THE HIGH LEVELS. ON THIS PATH, THE UPPER LEVEL WESTERLY WINDSHEAR, AND THE LOWERING OF THE OCEANIC HEAT POTENTIAL ABOUT 25S, WILL BECOME MORE AND MORE UNFAVOURABLE TO THE SYSTEM. BANSI SHOULD ADOPT HYBRID POST-TROPICAL FEATURES ON SUNDAY. FROM MONDAY, IT SHOULD TRACK SOUTH-EASTWARD UNDER THE INFLUENCE OF A TROUGH SOUTHWARD, AND BEGIN ITS EXTRATROPICAL TRANSITION. ON TUESDAY, THE LOW LEVEL CIRCULATION IS LIKELY TO MERGE WITH THE MID-LATITUDES TROUGH AND THE REMNANT SYSTEM IS LIKELY TO ACHIEVE ITS EXTRATROPICAL TRANSITION. THE WIND SPEED ARE FORECAST TO REMAIN STRONG WITHIN THE LLC UP TO MONDAY. THE REMNANT LOW SHOULD FILL UP ON WEDNESDAY.=