WTIO30 FMEE 310630



RSMC / TROPICAL CYCLONE CENTER / LA REUNION

TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)



0.A WARNING NUMBER: 17/5/20172018

1.A TROPICAL CYCLONE  5  (CEBILE)



2.A POSITION 2018/01/31 AT 0600 UTC:

WITHIN 15 NM RADIUS OF POINT 15.7 S / 77.6 E

(FIFTEEN    DECIMAL SEVEN   DEGREES SOUTH AND SEVENTY SEVEN

DECIMAL SIX   DEGREES EAST)

MOVEMENT : WEST 6 KT



3.A DVORAK ANALYSIS: 5.0/5.0/W 0.5/24 H



4.A CENTRAL PRESSURE: 962 HPA

5.A MAX AVERAGE WIND SPEED (10 MN): 80 KT

RADIUS OF MAXIMUM WINDS (RMW) :46 KM



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

28 KT NE: 260 SE: 350 SW: 390 NW: 220

34 KT NE: 150 SE: 200 SW: 200 NW: 150

48 KT NE: 110 SE: 150 SW: 150 NW: 110

64 KT NE: 90 SE: 100 SW: 100 NW: 90



7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1009 HPA / 1200 KM

8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION : DEEP



1.B FORECASTS:

12H: 2018/01/31 18 UTC: 15.7 S / 76.6 E, MAX WIND=090 KT, INTENSE

TROPICAL CYCLONE

24H: 2018/02/01 06 UTC: 15.9 S / 75.9 E, MAX WIND=095 KT, INTENSE

TROPICAL CYCLONE

36H: 2018/02/01 18 UTC: 16.3 S / 75.5 E, MAX WIND=090 KT, INTENSE

TROPICAL CYCLONE

48H: 2018/02/02 06 UTC: 17.0 S / 75.2 E, MAX WIND=085 KT, TROPICAL

CYCLONE

60H: 2018/02/02 18 UTC: 17.6 S / 75.3 E, MAX WIND=075 KT, TROPICAL

CYCLONE

72H: 2018/02/03 06 UTC: 18.3 S / 76.2 E, MAX WIND=055 KT, SEVERE

TROPICAL STORM



2.B LONGER-RANGE OUTLOOK :

96H: 2018/02/04 06 UTC: 21.1 S / 79.2 E, MAX WIND=045 KT,

POST-TROPICAL DEPRESSION

120H: 2018/02/05 06 UTC: 24.4 S / 80.6 E, MAX WIND=045 KT,

POST-TROPICAL DEPRESSION



2.C ADDITIONAL INFORMATION:

T=5.0- CI=5.0



OVER THE LAST 6 HOURS, CEBILE WIDE EYE PATTERN DID NOT EVOLVE A LOT.

A SLIGHT WEAKENING OCCURRED IN THE SOUTHERN SEMI-CIRCLE. BUT LAST

MICROWAVE DATA DO NOT SHOW ANY WEAKNESS. THE EYE KEEP ON CONTRACTING

SLOWLY BUT IS STILL WIDE LIMITING THE RSMC DVORAK ESTIMATES.



CEBILE ACCELERATED SLIGHTLY IN THE EARLY MORNING, STILL TRACKING

MAINLY WESTWARDS. THE SYSTEM IS CAUGHT BETWEEN A SUBTROPICAL RIDGE IN

THE SOUTH-WEST AND THE NEAR-EQUATORIAL RIDGE IN THE NORTH-EAST. THESE

TWO SYNOPTIC STRUCTURES ARE DRIVING OPPOSITE STEERING FLOWS. THE

SUBTROPICAL INFLUENCE IS LIKELY TO BE STRONGER AT SHORT RANGE.

HOWEVER, FROM TOMORROW, IT IS EXPECTED TO DECAY, THE NEAR-EQUATORIAL

RIDGE BECOMING THE MAIN STEERING FLOW PROGRESSIVELY. THIS DRIVES A

SHARP SOUTH-EASTWARD TURN FOLLOWED BY A GRADUAL ACCELERATION. THE

GUIDANCE DISPERSION REMAINS IMPORTANT BECAUSE OF THE UNCERTAINTY OVER

THE EXACT TRACK OF THE SYSTEM OVER THE NEXT DAYS. DIFFERENT SCENARIOS

SEEMS TO START CONVERGING TOWARD AN INTERMEDIATE SOLUTION. THE

CURRENT TRACK FORECAST IS MOSTLY BASED ON AN IFS AND GFS CONSENSUS.



UNTIL WEDNESDAY NIGHT, CEBILE SHOULD EVOLVE WITHIN QUASI-PERFECT

CONDITIONS CONCERNING WIND SHEAR, UPPER DIVERGENCE AND OCEANIC HEAT

CONTENT. WITH THE CURRENT CONTRACTION OF THE EYE, A INTENSIFICATION

IS STILL FORECAST AT SHORT RANGE. FROM THURSDAY, EQUATORWARD UPPER

LEVEL DIVERGENCE IS EXPECTED TO WEAKEN BUT THIS DECREASE SHOULD BE

OFFSET BY AN INCREASING POLARWARD CHANNEL OUTFLOW. HOWEVER, IF THE

MOTION IS SLOWER THAN EXPECTED WHEN IT SHOULD CURVE SOUTHEASTWARD,

THE SST SELF-INDUCED COOLING COULD SIGNIFICANTLY DECREASE CEBILE'S

INTENSITY. FROM FRIDAY EVENING, A ROSSBY WAVE BREAKING LOCATED WEST

OF THE SYSTEM WILL INCREASE QUICKLY THE NORTHWESTWARD VERTICAL

WINDSHEAR AND CEBILE'S INTENSITY IS FORECAST TO QUICKLY DECREASE AS

IT WILL MOVE OVER COOLER SURFACE SEA TEMPERATURE.=