WTIO30 FMEE 010029



RSMC / TROPICAL CYCLONE CENTER / LA REUNION

TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)



0.A WARNING NUMBER: 10/9/20172018

1.A SEVERE TROPICAL STORM  9  (FLAMBOYAN)



2.A POSITION 2018/05/01 AT 0000 UTC:

WITHIN 25 NM RADIUS OF POINT 17.2 S / 84.0 E

(SEVENTEEN    DECIMAL TWO   DEGREES SOUTH AND EIGHTY FOUR    DECIMAL

ZERO   DEGREES EAST)

MOVEMENT : SOUTH 7 KT



3.A DVORAK ANALYSIS: 3.5/3.5/W 0.5/12 H



4.A CENTRAL PRESSURE: 986 HPA

5.A MAX AVERAGE WIND SPEED (10 MN): 55 KT

RADIUS OF MAXIMUM WINDS (RMW) :56 KM



6.A EXTENSION OF WIND BY QUADRANTS (KM):

28 KT NE: 260 SE: 430 SW: 430 NW: 260

34 KT NE: 160 SE: 260 SW: 300 NW: 130

48 KT NE: 90 SE: 130 SW: 150 NW: 90





7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1009 HPA / 700 KM

8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION : DEEP



1.B FORECASTS:

12H: 2018/05/01 12 UTC: 18.5 S / 83.8 E, MAX WIND=050 KT,

POST-TROPICAL DEPRESSION

24H: 2018/05/02 00 UTC: 19.8 S / 84.0 E, MAX WIND=045 KT,

POST-TROPICAL DEPRESSION

36H: 2018/05/02 12 UTC: 21.5 S / 84.9 E, MAX WIND=040 KT,

POST-TROPICAL DEPRESSION

48H: 2018/05/03 00 UTC: 23.5 S / 86.4 E, MAX WIND=035 KT,

POST-TROPICAL DEPRESSION

60H: 2018/05/03 12 UTC: 26.3 S / 89.0 E, MAX WIND=035 KT,

EXTRATROPICAL DEPRESSION

72H: 2018/05/04 00 UTC: 29.2 S / 92.8 E, MAX WIND=040 KT,

EXTRATROPICAL DEPRESSION



2.B LONGER-RANGE OUTLOOK :







2.C ADDITIONAL INFORMATION:

T=3.5 CI=3.5+



DESPITE THE LACK OF SIGNIFICANT CHANGE OF THE CLOUD PATTERN IN

CLASSIC IMAGERY, LAST MICROWAVE DATA SHOW A CLEAR EVOLUTION TOWARDS A

SHEARED PATTERN. ON 2222Z SSMIS, DEEP CONVECTION IS LIMITED TO THE

SOUTH-EASTERN QUADRANT, AT SOME DISTANCE OF THE CENTER. INTENSITY IS

THEREFORE DOWNGRADED TO 55KT.



FLAMBOYAN DO NOT BENEFIT ANYMORE FROM A CONDUCIVE ENVIRONMENT FOR

TROPICAL DEEPENING, WITH THE INCREASE OF THE VERTICAL WIND SHEAR

(ANALYSED AT 18Z AROUND 25KT BY CIMSS). MOREOVER, OCEANIC CONTENT

WILL DECAY SOUTH OF 18S. HOWEVER, DUE TO BAROCLINIC PROCESSES WHEN

INTERACTING WITH UPPER ANOMALIES, TEMPORARY DEEPENING ARE POSSIBLE

TODAY AND THURSDAY.



FLAMBOYAN IS ON ITS TRACK TO ROUND THE LOW TO MID LEVEL SUBTROPICAL

RIDGE LOCATED TO IT EAST WITH A GRADUAL SOUTH-EASTWARDS TURN EXPECTED

DURING THE WHOLE FORECAST PERIOD. FROM WEDNESDAY, IT SHOULD

ACCELERATE AHEAD OF A DEEP MID-LATITUDES TROUGH. THE FORECAST TRACK

CHANGED IN ORDER TO TAKE INTO ACCOUNT THE LATEST ANALYSIS DATA

(ESPECIALLY IN DIRECTIONS).=