WTIO30 FMEE 301811



RSMC / TROPICAL CYCLONE CENTER / LA REUNION

TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)



0.A WARNING NUMBER: 15/5/20172018

1.A TROPICAL CYCLONE  5  (CEBILE)



2.A POSITION 2018/01/30 AT 1800 UTC:

WITHIN 20 NM RADIUS OF POINT 15.9 S / 78.8 E

(FIFTEEN    DECIMAL NINE   DEGREES SOUTH AND SEVENTY EIGHT    DECIMAL

EIGHT   DEGREES EAST)

MOVEMENT : WEST 4 KT



3.A DVORAK ANALYSIS: 5.0/5.5/S 0.0/12 H



4.A CENTRAL PRESSURE: 958 HPA

5.A MAX AVERAGE WIND SPEED (10 MN): 85 KT

RADIUS OF MAXIMUM WINDS (RMW) :65 KM



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

28 KT NE: 260 SE: 310 SW: 310 NW: 220

34 KT NE: 150 SE: 190 SW: 190 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): 1010 HPA / 1300 KM

8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION : DEEP



1.B FORECASTS:

12H: 2018/01/31 06 UTC: 15.9 S / 78.0 E, MAX WIND=090 KT, INTENSE

TROPICAL CYCLONE

24H: 2018/01/31 18 UTC: 16.0 S / 77.2 E, MAX WIND=095 KT, INTENSE

TROPICAL CYCLONE

36H: 2018/02/01 06 UTC: 16.3 S / 76.6 E, MAX WIND=100 KT, INTENSE

TROPICAL CYCLONE

48H: 2018/02/01 18 UTC: 16.8 S / 76.1 E, MAX WIND=095 KT, INTENSE

TROPICAL CYCLONE

60H: 2018/02/02 06 UTC: 17.5 S / 75.8 E, MAX WIND=090 KT, INTENSE

TROPICAL CYCLONE

72H: 2018/02/02 18 UTC: 18.2 S / 76.0 E, MAX WIND=085 KT, TROPICAL

CYCLONE



2.B LONGER-RANGE OUTLOOK :

96H: 2018/02/03 18 UTC: 20.1 S / 77.9 E, MAX WIND=065 KT, TROPICAL

CYCLONE

120H: 2018/02/04 18 UTC: 24.4 S / 81.0 E, MAX WIND=050 KT,

POST-TROPICAL DEPRESSION



2.C ADDITIONAL INFORMATION:

T=5.0 CI=5.5-



OVER THE LAST 6 HOURS, CEBILE WIDE EYE PATTERN HAS REMAINED VERY

STABLE. 1318Z 37GHZ WINDSAT MICROWAVE IMAGERY SHOWS AN IMPRESSIVE

PINK RING OF INTENSE CONVECTION. SINCE 1200Z, THE DVORAK ESTIMATES

HAS SLIGHTLY DECREASED. CEBILE INTENSITY REMAINS ESTIMATED AROUND THE

TROPICAL CYCLONE MAXIMAL STAGE (85KT) ACCORDING WITH THE 1254Z SATCON

ASSESSMENT.



CEBILE IS STILL TRACKING 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 AVAILABLE MODELS SUGGEST A SLOW WESTWARD TRACK

OVER THE NEXT DAYS, SUGGESTING THAT THE SUBTROPICAL INFLUENCE IS

SLIGHTLY STRONGER. OVER THE NEXT DAYS, THE SUBTROPICAL RIDGE IS

WEAKENING BEFORE THE NEAR-EQUATORIAL RIDGE BECOMES THE MAIN STEERING

FLOW FRIDAY. THIS DRIVES A SHARP SOUTH-EASTWARD TURN FOLLOWED BY A

GRADUAL ACCELERATION. THE GUIDANCE DISPERSION REMAINS HIGH BECAUSE OF

THE UNCERTAINTY OVER THE EXACT COURSE OF THE SYSTEM OVER THE NEXT

DAYS, BETWEEN A NORTH-WESTWARD TRACK SUGGESTED BY IFS AND A

SOUTH-WESTWARD MOTION FOR GFS. HOWEVER, THE AGREEMENT OVER THE TIMING

OF THE TURN IS GOOD.



UNTIL WEDNESDAY NIGHT, CEBILE SHOULD TRACK WITHIN QUASI-PERFECT

CONDITIONS CONCERNING WIND SHEAR, UPPER DIVERGENCE AND OCEANIC HEAT

CONTENT, WHICH IS EVEN INCREASING WEST OF 80E. FROM THURSDAY,

EQUATORWARD UPPER LEVEL DIVERGENCE IS EXPECTED TO WEAKEN BUT THIS

DECREASE SHOULD BE OFFSET BY AN INCREASING POLERWARD 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 FORECASTED

TO QUICKLY DECREASE AS IT WILL MOVE OVER COOLER SURFACE SEA

TEMPERATURE.=