WTIO30 FMEE 210034 RSMC / TROPICAL CYCLONE CENTER / LA REUNION TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN) 0.A WARNING NUMBER: 40/8/20152016 1.A TROPICAL CYCLONE 8 (FANTALA) 2.A POSITION 2016/04/21 AT 0000 UTC: WITHIN 20 NM RADIUS OF POINT 12.1 S / 54.9 E (TWELVE DECIMAL ONE DEGREES SOUTH AND FIFTY FOUR DECIMAL NINE DEGREES EAST) MOVEMENT : SOUTH-EAST 8 KT 3.A DVORAK ANALYSIS: 4.0/4.5/W 1.0/12 H 4.A CENTRAL PRESSURE: 975 HPA 5.A MAX AVERAGE WIND SPEED (10 MN): 70 KT RADIUS OF MAXIMUM WINDS (RMW) :37 KM 6.A EXTENSION OF WIND BY QUADRANTS (KM): 28 KT NE: 140 SE: 90 SW: 100 NW: 110 34 KT NE: 70 SE: 60 SW: 60 NW: 60 48 KT NE: 60 SE: 60 SW: 60 NW: 60 64 KT NE: 50 SE: 50 SW: 50 NW: 50 7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1008 HPA / 300 KM 8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION : DEEP 1.B FORECASTS: 12H: 2016/04/21 12 UTC: 13.0 S / 55.2 E, MAX WIND=060 KT, SEVERE TROPICAL STORM 24H: 2016/04/22 00 UTC: 13.4 S / 55.1 E, MAX WIND=050 KT, SEVERE TROPICAL STORM 36H: 2016/04/22 12 UTC: 13.5 S / 54.6 E, MAX WIND=040 KT, MODERATE TROPICAL STORM 48H: 2016/04/23 00 UTC: 13.3 S / 53.6 E, MAX WIND=035 KT, MODERATE TROPICAL STORM 60H: 2016/04/23 12 UTC: 12.8 S / 52.3 E, MAX WIND=035 KT, MODERATE TROPICAL STORM 72H: 2016/04/24 00 UTC: 12.2 S / 51.1 E, MAX WIND=030 KT, TROPICAL DEPRESSION 2.B LONGER-RANGE OUTLOOK : 96H: 2016/04/25 00 UTC: 9.9 S / 47.8 E, MAX WIND=025 KT, LOW 120H: 2016/04/26 00 UTC: 8.4 S / 43.1 E, MAX WIND=020 KT, LOW 2.C ADDITIONAL INFORMATION: T=4.0+ CI=4.5+ FANTALA'S CLOUD PATTERN IS BECOMING WORSE AND WORSE : THE EYE PATTERN DISAPPEARED FROM 21Z, LEAVING A CDO WHERE A FADING SPOT CAN STILL BE SPOTTED. 2239Z AMSU-B MW IMAGE SHOW THAT THE CONVECTION RING IS NOW ONLY PARTIAL IN THE SOUTH-EASTERN QUADRANT. THE CLOUD PLUM ASYMMETRY SUGGEST THAT A LIGHT NORTH-EASTERLY CONSTRAINT IS APPEARING ALOFT, WHICH IS CONFIRMED BY THE CIMSS SHEAR ESTIMATE AT APPROXIMATELY 10KT. UNTIL THIS EVENING, FANTALA'S TRACK IS STEERED BY TWO ATMOSPHERIC PATTERNS : THE NEAR EQUATORIAL RIDGE BUILDING IN ITS NORTH-EAST AND A WIDE MID-LATITUDES TROUGH COMING FROM THE SOUTH-WEST. A NEW HIGH GEOPOTENTIAL CELL FOLLOWING THE TROUGH IS THEN SETTLING OVER THE SOUTH OF MADAGASCAR AND SHOULD PROGRESSIVELY EXTEND NORTHWARD. FANTALA SHOULD SLOW AGAIN TONIGHT AND EVEN REMAINS STATIONARY BEFORE BEGINNING TO TRACK NORTH-WESTWARDS FRIDAY EVENING, STEERED BY THIS WIDE RIDGE IN ITS SOUTH-WEST. FOR THE FOLLOWING DAYS, THE SYSTEM IS LIKELY TO REMAIN STEERED BY THIS HIGH SUBTROPICAL CELL IN THE LOW AND MID TROPOSPHERE, AND SHOULD KEEP ON A NORTH-WESTWARD TRACK. ON THIS PART OF THE TRACK, THE AGREEMENT BETWEEN THE MODELS IS A BIT LOWER WITH THE GFS TRACK STILL MORE SOUTHWARD THAN THE ECMWF ONE. AS IT HEADS BACK ON ITS TRACK, FANTALA IS CURRENTLY PASSING OVER AN OCEANIC AREA PREVIOUSLY COOLED BY ITSELF 4 DAYS AGO. THIS LACK OF OCEANIC ENERGY SHOULD GRADUALLY WEAKEN THE SYSTEM. WITH A NEW SLOW TRACK TURN EXPECTED FRIDAY OVER A LOW OHC AREA AND SIGNIFICANTLY LESS FAVORABLE ATMOSPHERIC CONDITIONS (WEAKENING OF THE UPPER LEVEL DIVERGENCE ESPECIALLY EVEN ON THE POLAR SIDE, INCREASE OF THE NORTHERLY SHEAR MORE SIGNIFICANTLY FROM SATURDAY WHEN IT TURNS WESTERLY, VERY DRY MID-LEVEL AIR MASS SURROUNDING THE SYSTEM FROM FRIDAY AND BEYOND), FANTALA'S ENVIRONMENT SHOULD LEAD TO A SUSTAINED WEAKENING OVER THE WEEK-END AND FURTHER. THIS INTENSITY FORECAST IS CONSISTENT WITH THE LAST ECMWF ENSEMBLE PREDICTION RUN, WHICH CONFIRMS A GRADUAL DECREASE OF THE STORM SIGNAL THROUGHOUT THE WEEK-END AND THE BEGINNING OF NEXT WEEK.=