WTIO30 FMEE 101802



RSMC / TROPICAL CYCLONE CENTER / LA REUNION

TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)



0.A WARNING NUMBER: 6/4/20152016

1.A MODERATE TROPICAL STORM  4  (DAYA)



2.A POSITION 2016/02/10 AT 1800 UTC:

WITHIN 20 NM RADIUS OF POINT 24.0 S / 52.6 E

(TWENTY FOUR    DECIMAL ZERO   DEGREES SOUTH AND FIFTY TWO    DECIMAL

SIX   DEGREES EAST)

MOVEMENT : SOUTH-EAST 8 KT



3.A DVORAK ANALYSIS: 2.5/2.5/D 1.0/24 H



4.A CENTRAL PRESSURE: 993 HPA

5.A MAX AVERAGE WIND SPEED (10 MN): 35 KT

RADIUS OF MAXIMUM WINDS (RMW) :46 KM



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

28 KT NE: 130 SE: 130 SW: 90 NW: 90

34 KT NE: 60 SE: 60 SW: 60 NW: 60







7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1003 HPA / 800 KM

8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION : DEEP



1.B FORECASTS:

12H: 2016/02/11 06 UTC: 25.1 S / 54.1 E, MAX WIND=035 KT, MODERATE

TROPICAL STORM

24H: 2016/02/11 18 UTC: 26.9 S / 55.5 E, MAX WIND=040 KT, MODERATE

TROPICAL STORM

36H: 2016/02/12 06 UTC: 29.3 S / 56.7 E, MAX WIND=040 KT,

POST-TROPICAL DEPRESSION

48H: 2016/02/12 18 UTC: 32.9 S / 58.3 E, MAX WIND=040 KT,

POST-TROPICAL DEPRESSION

60H: 2016/02/13 06 UTC: 37.9 S / 61.3 E, MAX WIND=040 KT,

POST-TROPICAL DEPRESSION





2.B LONGER-RANGE OUTLOOK :







2.C ADDITIONAL INFORMATION:

T=CI=2.5+



OVER THE LAST SIX HOURS, THE CLOUD PATTERN HAS KEPT ON IMPROVING WITH

A CURVED BAND WRAPING A LITTLE MORE THAN 0.5 AROUND THE CENTRE,

BECOMING LARGER, AS SEEN ON THE 1109Z AND 1250Z SSMI MICRO-WAVE

IMAGES, AND WITH A BETTER CURVATURE OF THE LOW LEVEL AS SEEN ON THE

DMPS-F17 37GHZ DATA.

ALL THESE OBSERVATION DATA SUGGEST THAT THE SYSTEM HAS REACHED THE

MODERATE TROPICAL STORM STAGE, AND HAS BEEN NAMED.



THE UPPER LEVEL CONDITIONS REMAIN CONDUCIVE WITH AN OUTFLOW CHANNEL

BUILDING ON THE POLAR SIDE. INTENSIFICATION SHOULD GOING ON DURING

THE NEXT 24 HOURS.



THE PARABOLIC TRACK OF THE SYSTEM IS STEERED BY BOTH A CUT-OFF LOW IN

THE SOUTH-WEST AND A HIGH GEOPOTENTIAL AREA IN THE EAST. UNDER THE

JOINED INFLUENCE OF THESE TWO SYNOPTIC STRUCTURES, THE AVAILABLE NWP

MODELS STILL FORECAST SIMILAR TRACKS BUT WITH A LIGHT DISPERSION

INCREASE DUE TO SOME ANALYSIS DIFFERENCES. THUS, THE SYSTEM HAS

ALREADY TURNED SOUTH-EASTWARD AND BEGAN TO ACCELERATE. THE

ENVIRONMENTAL CONDITIONS REMAIN CONDUCIVE UNTIL THURSDAY EVENING.

FRIDAY, THE SYSTEM IS TRACKING OVER LOW ENERGETIC WATERS AND SHIFTS

GRADUALLY UNDER A BRANCH OF THE SUBTROPICAL WESTERLY JET. IT SHOULD

THEN BEGIN A RELATIVELY QUICK EXTRATROPICAL TRANSITION BEFORE MERGING

WITH A BAROCLINIC LOW SATURDAY.=