WTIO30 FMEE 160054



RSMC / TROPICAL CYCLONE CENTER / LA REUNION

TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)



0.A WARNING NUMBER: 8/6/20142015

1.A MODERATE TROPICAL STORM  6  (CHEDZA)



2.A POSITION 2015/01/16 AT 0000 UTC:

WITHIN 30 NM RADIUS OF POINT 19.3 S / 43.4 E

(NINETEEN    DECIMAL THREE   DEGREES SOUTH AND FORTY THREE    DECIMAL

FOUR   DEGREES EAST)

MOVEMENT : EAST 12 KT



3.A DVORAK ANALYSIS: 3.0/3.0/D 1.5/24 H



4.A CENTRAL PRESSURE: 987 HPA

5.A MAX AVERAGE WIND SPEED (10 MN): 40 KT

RADIUS OF MAXIMUM WINDS (RMW) :56 KM



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

28 KT NE: 280 SE: 240 SW: 220 NW: 300

34 KT NE: 90 SE: 150 SW: 150 NW: 90







7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1003 HPA / 900 KM

8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION : MEDIUM



1.B FORECASTS:

12H: 2015/01/16 12 UTC: 19.9 S / 44.3 E, MAX WIND=050 KT, SEVERE

TROPICAL STORM

24H: 2015/01/17 00 UTC: 21.1 S / 46.3 E, MAX WIND=025 KT, INLAND

36H: 2015/01/17 12 UTC: 21.6 S / 49.0 E, MAX WIND=020 KT, DISTURBANCE

48H: 2015/01/18 00 UTC: 21.5 S / 51.2 E, MAX WIND=025 KT, TROPICAL

DISTURBANCE

60H: 2015/01/18 12 UTC: 21.7 S / 52.4 E, MAX WIND=030 KT, TROPICAL

DEPRESSION

72H: 2015/01/19 00 UTC: 22.0 S / 53.1 E, MAX WIND=035 KT, MODERATE

TROPICAL STORM



2.B LONGER-RANGE OUTLOOK :

96H: 2015/01/20 00 UTC: 23.2 S / 53.6 E, MAX WIND=040 KT, MODERATE

TROPICAL STORM

120H: 2015/01/21 00 UTC: 24.9 S / 54.4 E, MAX WIND=050 KT,

POST-TROPICAL DEPRESSION



2.C ADDITIONAL INFORMATIONS:

T=CI=3.0-



1913Z ASCAT SWATH SHOWS GALE FORCE WINDS EXTENDING OVER A LARGE PART

OF CIRCULATION IN THE SOUTHERN SEMI-CIRCLE.

DVORAK SIGNATURE CONFIRMS THAT MODERATE TROPICAL STORM STAGE HAS

PROBABLY BEEN REACHED AND CHEDZA HAS THERFORE BEEN NAMED BY THE

METEOROLOGICAL SERVICES OF MADAGASCAR.



UNDER THE STEERING INFLUENCE OF THE MID-LEVELS NEAR-EQUATORIAL RIDGE

IN ITS NORTH, SYSTEM IS GLOBALLY TRACKING EASTWARDS SINCE 12Z.

CHEDZA IS LOCATED UNDER AN UPPER-LEVEL TROUGH AXIS IN A MODERATE

SHEARED AREA AND LIMITED EQUATORWARD UPPER-LEVEL OUTFLOW.

SYSTEM INTENSIFICATION IS MAINLY LINKED TO A VERY GOOD LOW/MID LEVEL

CONVERGENCE ON ITS BOTH EDGES, HIGH OCEANIC HEAT CONTENTS OVER SEA

SURFACE TEMPERATURE AT ABOUT 29/30 DG AND A VERY GOOD POLEWARD

OUTFLOW CHANNEL ALOFT SUSTAINED BY THE SUBTROPICAL WESTERLY JET.



THIS ENVIRONMENTAL CONDITIONS ARE NOT EXPECTED TO CHANGE WITHIN THE

NEXT 12 HOURS AND A GRADUAL BUT SLOW FURTHER INTENSIFICATION IS

THEREFORE FORECAST UNTIL THE SYSTEM MAKES LANDFALL OVER THE WESTERN

MADAGASCAR COASTLINE IN THE AREA OF THE TSIRIBIHINA RIVER ESTUARY

(BETWEEN TAMBOHORANI AND BELO-SUR-MER).



MOST OF THE AVAILABLE NWP MODELS SUGGEST THAT THE MID-LEVEL

CIRCULATION COULD RESIST TO THE CROSSING PATH OVER MADAGASCAR AND

THAT THE LOW LEVEL CIRCULATION COULD RE-DEVELOP AS THE SYSTEM GET

BACK OVERSEA ON THE SOUTH-EAST OF MADAGASCAR ON SATURDAY.

ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BE MARGINAL BY THAT TIME

EXPERIENCING A MODERATE WEST-NORTH-WESTERLY VERTICAL WINDSHEAR

HOWEVER WEAKENING ON SUNDAY AND IN THE SAME DIRECTION THAN THE

SYSTEM'S MOTION,

BUT AS IN THE MOZAMBIQUE CHANNEL BEFORE THE LANDFALL, IN A VERY GOOD

LOW LEVEL CONVERGENCE ENVIRONMENT OVER FAVOURABLE HEAT OCEANIC

CONTENTS AND SUSTAINED BY AN EFFICIENT POLEWARD UPPER-LEVEL OUTFLOW.

ECMWF AND GFS NWP MODELS SUGGEST A GRADUAL FURTHER INTENSIFICATION ON

A EAST-SOUTH-EASTWARDS TRACK AT FIRST.

ON AND AFTER MONDAY, A MID-LEVEL TROUGH ARRIVES IN THE SOUTH AND

CHEDZA IN THEN EXPECTED TO RECURVE SOUTH-SOUTH-EASTWARDS AND TO KEEP

ON INTENSIFY.=