WTIO30 FMEE 120111 RSMC / TROPICAL CYCLONE CENTER / LA REUNION TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN) 0.A WARNING NUMBER: 10/5/20142015 1.A TROPICAL CYCLONE 5 (BANSI) 2.A POSITION 2015/01/12 AT 0000 UTC: WITHIN 20 NM RADIUS OF POINT 17.4 S / 55.2 E (SEVENTEEN DECIMAL FOUR DEGREES SOUTH AND FIFTY FIVE DECIMAL TWO DEGREES EAST) MOVEMENT : SOUTH-SOUTH-EAST 2 KT 3.A DVORAK ANALYSIS: 5.0/5.0/D 1.5/12 H 4.A CENTRAL PRESSURE: 962 HPA 5.A MAX AVERAGE WIND SPEED (10 MN): 80 KT RADIUS OF MAXIMUM WINDS (RMW) :22 KM 6.A EXTENSION OF WIND BY QUADRANTS (KM): 28 KT NE: 240 SE: 220 SW: 190 NW: 240 34 KT NE: 190 SE: 190 SW: 150 NW: 190 48 KT NE: 100 SE: 100 SW: 80 NW: 100 64 KT NE: 60 SE: 60 SW: 50 NW: 60 7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1008 HPA / 600 KM 8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION : UNKNOWN 1.B FORECASTS: 12H: 2015/01/12 12 UTC: 17.9 S / 55.7 E, MAX WIND=090 KT, INTENSE TROPICAL CYCLONE 24H: 2015/01/13 00 UTC: 18.0 S / 56.5 E, MAX WIND=100 KT, INTENSE TROPICAL CYCLONE 36H: 2015/01/13 12 UTC: 18.0 S / 57.1 E, MAX WIND=110 KT, INTENSE TROPICAL CYCLONE 48H: 2015/01/14 00 UTC: 18.1 S / 57.8 E, MAX WIND=115 KT, INTENSE TROPICAL CYCLONE 60H: 2015/01/14 12 UTC: 18.5 S / 58.3 E, MAX WIND=115 KT, INTENSE TROPICAL CYCLONE 72H: 2015/01/15 00 UTC: 19.4 S / 59.1 E, MAX WIND=110 KT, INTENSE TROPICAL CYCLONE 2.B LONGER-RANGE OUTLOOK : 96H: 2015/01/16 00 UTC: 22.2 S / 61.2 E, MAX WIND=090 KT, INTENSE TROPICAL CYCLONE 120H: 2015/01/17 00 UTC: 26.2 S / 65.2 E, MAX WIND=070 KT, TROPICAL CYCLONE 2.C ADDITIONAL INFORMATIONS: T AND CI=5.0+ SYSTEM KEEPS ON INTENSIFYING. SINCE 1930Z, T-NUMBER WAVES AROUND 5.5 BUT DVORAK CONSTRAINTS OVER 12,18 AND 24 HOURS DOES NOT ALLOW TO HAVE A FINAL T-NUMBER MORE THAN FT=5.0. TO AVOID METEOSAT7 PARALLAX ERROR, AFORE-MENTIONED POSITION AND MOTION ARE BASED ON 1539Z SSMIS-F18 SWATH AND COLORADO RADAR (THE EYE-WALL IS HOWEVER PARTIALLY COVERED ON OUR SCOPE). BANSI KEEPS ON DRIFTING SLOWLY SOUTHWARDS UNDER THE MID-LEVEL STEERING FLOWS GENERATED BY A RIDGE IN ITS NORTH-EAST AND A TROUGH IN ITS SOUTH. ANOTHER MID-LEVEL RIDGE OVER MADAGASCAR INDUCES A SLOWING DOWN MOTION AND BANSI SHOULD THEREFORE BE TEMPORARILY QUASI-STATIONARY. WITHIN THE NEXT 24 HOURS, THE MID-LEVEL RIDGE IN THE NORTH-EAST IS EXPECTED TO PROGRESSIVELY SHIFT TOWARDS THE NORTH OF THE SYSTEM AND A NEW MID-LEVEL RIDGE EXPECTED TO REBUILD IN ITS SOUTH. BANSI IS THEREFORE EXPECTED TO PROGRESSIVELY RECURVE SOUTH-EASTWARDS THEN EASTWARDS. ON AND AFTER WEDNESDAY, THE MID-LEVEL RIDGE SHIFTS BACK IN THE EAST OF THE SYSTEM AND A COL BUILDS IN ITS SOUTH, A SOUTH-EASTWARDS MOTION IS THEN EXPECTED. BANSI IS THEN EXPECTED TO KEEPS ON TRACKING AND ACCELERATING SOUTH-EASTWARDS UNTIL SATURDAY. ON THIS FORECAST TRACK, ENVIRONMENTAL CONDITIONS ARE VERY FAVOURABLE ON MONDAY, TUESDAY AND WEDNESDAY UNDER THE UPPER LEVEL RIDGE AXIS AS AT LEAST 2 UPPER LEVEL CHANNELS EQUATOR-WARD AND POLEWARD TAKE PLACE WITHIN THE PERIOD. A THIRD ONE TOWARDS THE EAST IS EXPECTED TO TEMPORARILY EXIST ON TUESDAY. ON AND AFTER THURSDAY, BANSI SHIFTS SOUTH OF THE UPPER LEVEL RIDGE AXIS AND KEEPS ONLY ITS POLEWARD OUTFLOW CHANNEL. A WEST-NORTH-WESTERLY VERTICAL WINDSHEAR STRENGTHENS ON FRIDAY OVER LIMITED HEAT OCEANIC CONTENTS. THERE IS AN IMPORTANT LIKELIHOOD THAT A VERY DANGEROUS INTENSE TROPICAL CYCLONE REPRESENTS A POTENTIAL THREAT FOR THE MASCAREIGNES WITHIN SEVERAL DAYS (FROM MONDAY TO THURSDAY). THE INHABITANTS OF THE MASCAREIGNES ISLANDS SHOULD THEREFORE CLOSELY MONITOR THE PROGRESS OF THIS DANGEROUS SYSTEM WITHIN THE NEXT DAYS.=