WTIO30 FMEE 170107 RSMC / TROPICAL CYCLONE CENTER / LA REUNION TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN) 0.A WARNING NUMBER: 24/8/20152016 1.A INTENSE TROPICAL CYCLONE 8 (FANTALA) 2.A POSITION 2016/04/17 AT 0000 UTC: WITHIN 10 NM RADIUS OF POINT 11.1 S / 53.5 E (ELEVEN DECIMAL ONE DEGREES SOUTH AND FIFTY THREE DECIMAL FIVE DEGREES EAST) MOVEMENT : WEST-NORTH-WEST 9 KT 3.A DVORAK ANALYSIS: 6.0/6.0/S 0.0/6 H 4.A CENTRAL PRESSURE: 939 HPA 5.A MAX AVERAGE WIND SPEED (10 MN): 105 KT RADIUS OF MAXIMUM WINDS (RMW) :15 KM 6.A EXTENSION OF WIND BY QUADRANTS (KM): 28 KT NE: 120 SE: 300 SW: 370 NW: 120 34 KT NE: 90 SE: 170 SW: 190 NW: 90 48 KT NE: 60 SE: 90 SW: 90 NW: 60 64 KT NE: 50 SE: 60 SW: 60 NW: 50 7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1004 HPA / 300 KM 8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION : DEEP 1.B FORECASTS: 12H: 2016/04/17 12 UTC: 10.2 S / 51.7 E, MAX WIND=110 KT, INTENSE TROPICAL CYCLONE 24H: 2016/04/18 00 UTC: 9.4 S / 50.2 E, MAX WIND=115 KT, INTENSE TROPICAL CYCLONE 36H: 2016/04/18 12 UTC: 9.3 S / 49.4 E, MAX WIND=110 KT, INTENSE TROPICAL CYCLONE 48H: 2016/04/19 00 UTC: 9.7 S / 49.4 E, MAX WIND=100 KT, INTENSE TROPICAL CYCLONE 60H: 2016/04/19 12 UTC: 10.1 S / 49.9 E, MAX WIND=085 KT, TROPICAL CYCLONE 72H: 2016/04/20 00 UTC: 10.8 S / 51.0 E, MAX WIND=075 KT, TROPICAL CYCLONE 2.B LONGER-RANGE OUTLOOK : 96H: 2016/04/21 00 UTC: 13.9 S / 53.8 E, MAX WIND=085 KT, TROPICAL CYCLONE 120H: 2016/04/22 00 UTC: 15.6 S / 55.5 E, MAX WIND=055 KT, SEVERE TROPICAL STORM 2.C ADDITIONAL INFORMATION: T=CI=6.0+ OVER THE LAST SIX HOURS, FANTALA INTENSITY CONTINUED ON A SLIGHT DECAY, ACCORDING TO INFRARED IMAGES. THE EYE GOT WARMER, BUT THE DEEP CONVECTION RING EVEN IF IT REMAINED RATHER COLD, ITS SIZE SIGNIFICANTLY DECAYED. FANTALA INTENSITY WAS REDUCED BECAUSE OF ITS SMALL SIZE. NEVERTHELESS, TROPICAL CYCLONE FANTALA IS EXTREMELY DANGEROUS, AND HEADING TOWARDS THE FARQUAHR ARCHIPELAGO. AT 00 UTC, THE EYE IS A LITTLE LESS THAN 300 KM TO THE EAST-SOUTH-EAST OF THE SOUTHERNMOST ISLANDS (FARQUAHR ATOLL - SEYCHELLES). THE SYSTEM, AS EXPECTED, CONTINUED ITS NORTHWESTWARDS TRACK OVER THE NORTHERN AND NORTHEASTERN SIDE OF A HIGH GEOPOTENTIAL CELL LOCATED SOUTH OF MADAGASCAR, WITH A RIDGE AXIS OVER MADAGASCAR. THIS RIDGE AXIS SHOULD MAINTAIN TO THE SOUTH-WEST OF FANTALA WITHIN THE NEXT 48 HOURS. ON THIS TRACK, FANTALA IS NOW A SERIOUS THREAT FOR THE SEYCHELLES FARQUAHR ISLANDS (THE SOUTHERN GROUP MAINLY) WITH A POTENTIAL DIRECT HIT WITHIN THE NEXT 24-36 HOURS (RARE EVENT - LAST ONE IS BONDO IN DEC 2006 AND NO OCCURENCE KNOWN BEFORE SINCE THE BEGINNING OF THE SATELLITE ERA). LAST AVAILABLE DATA SUGGEST A STORM SURGE INFERIOR TO 1 METER GENERALLY, UP TO 2 METERS LOCALLY, ESPECIALLY CLOSER TO THE CORE. FROM SUNDAY, THE SOUTHERN HIGH PRESSURE SHOULD WEAKEN. MONDAY, WITH THE BUILDING OF A NEAR EQUATORIAL RIDGE IN THE NORTH-EAST, FANTALA COULD ADOPT PROGRESSIVELY A SOUTH-EASTWARD TRACK. EXACT LOCATION OF THE U-TURN IS STILL UNCERTAIN, EVEN IF LAST DETERMINISTIC MODEL GUIDANCE TEND TO CONVERGENCE. IN THE MIDDLE OF THE NEXT WEEK, SEVERAL STEERING FLOW MAY INFLUENCE THE SYSTEM, WHICH ADD UNCERTAINTIES ON THE TRACK FORECAST. WEDNESDAY, A TROUGH MAY ARRIVE SOUTH OF THE MASCAREIGNES ARCHIPELAGO, JUST IN FRONT OF A NEW SUBTROPICAL RIDGE. DEPENDING ON THE TIMING OF THE ARRIVALS AND THE STRENGTH OF THESE CIRCULATIONS, FANTALA COULD GO WEST-NORTH-WEST (GFS 06Z AND 18Z) IN THE ANTICYCLONIC FLOW OR EAST OR SOUTH-EAST (GFS 12Z AND EURO 12Z). ENSEMBLE FORECAST SHOW THE TWO POSSIBILITIES WITHOUT A SIGNIFICANT SIGNAL ON ONE OF THESE OPTIONS. THE CURRENT TRACK FORECAST IS BASED ON A CONSENSUS OF THE LAST EURO AND GFS OUTPUT, WITH A RATHER SOUTH-EASTWARD CHOICE AT THE END. THE INTENSITY FORECAST IS DIFFICULT DUE TO THE SMALL SIZE OF THE SYSTEM. THE INTENSITY FLUCTUATES RAPIDLY WITH SMALL FLUCTUATIONS OF THE ENVIRONMENTAL CONDITIONS. WITHOUT ANY EARLY INDICATIONS OF THE BEGINNING OF AN ERC AND GIVEN THE EXPECTED IMPROVEMENT OF THE UPPER LEVEL DIVERGENCE WITHIN THE NEXT 24 HOURS, FANTALA IS LIKELY TO DEEPEN SLOWLY. FROM MONDAY, ON THE SOUTH-EASTWARD TRACK, THE SELF INDUCED SST COOLING COULD BECOME THE MAIN FACTOR OF THE WEAKENING OF THE SYSTEM AS ATMOSPHERIC FACTORS ARE EXPECTED TO BE EXCELLENT FOR MOST OF THE FORECAST PERIOD (SLIGHT DETERIORATION POSSIBLE AT THE END OF THE FORECAST).