WTIO30 FMEE 110040



RSMC / TROPICAL CYCLONE CENTER / LA REUNION

TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)



0.A WARNING NUMBER: 7/4/20152016

1.A MODERATE TROPICAL STORM  4  (DAYA)



2.A POSITION 2016/02/11 AT 0000 UTC:

WITHIN 20 NM RADIUS OF POINT 24.5 S / 53.0 E

(TWENTY FOUR    DECIMAL FIVE   DEGREES SOUTH AND FIFTY THREE

DECIMAL ZERO   DEGREES EAST)

MOVEMENT : SOUTH-EAST 5 KT



3.A DVORAK ANALYSIS: 2.5/3.0/D 1.0/24 H



4.A CENTRAL PRESSURE: 992 HPA

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

RADIUS OF MAXIMUM WINDS (RMW) :46 KM



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

28 KT NE: 150 SE: 240 SW: 190 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 12 UTC: 26.1 S / 54.8 E, MAX WIND=035 KT, MODERATE

TROPICAL STORM

24H: 2016/02/12 00 UTC: 28.3 S / 56.4 E, MAX WIND=035 KT, MODERATE

TROPICAL STORM

36H: 2016/02/12 12 UTC: 31.2 S / 57.8 E, MAX WIND=040 KT,

POST-TROPICAL DEPRESSION

48H: 2016/02/13 00 UTC: 35.2 S / 59.0 E, MAX WIND=040 KT,

POST-TROPICAL DEPRESSION

60H: 2016/02/13 12 UTC: 39.3 S / 62.3 E, MAX WIND=040 KT,

POST-TROPICAL DEPRESSION





2.B LONGER-RANGE OUTLOOK :







2.C ADDITIONAL INFORMATION:

T=2.5+ CI=3.0-



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

A CURVED BAND IN THE EASTERN PART, BUT DURING THE LAST HOURS, DEEP

CONVECTION IN THE WESTERN PART SHOWS SIGNS OF WEAKENING DUE TO THE

NORTHWESTERLY UPPER LEVEL CONSTRAINT (CIRRUS ARCUS). THE GCOM 2140Z

DATA SHOW A TILT BETWEEN LOW LEVEL AND CONVECTION, AND ON THE LAST IR

SATELLITE IMAGERY, DEEP CONVECTION IS CLEARLY WEAKENING NEAR THE

CENTER.

1740Z ASCAT DATA CORROBORATE EXISTING GALE FORCE WINDS, WITH STRONGER

WINDS IN THE EASTERN SEMI-CIRCLE.



THE SYSTEM SEEM TO HAVE REACHED ITS MAXIMUM OF INTENSITY, AND SHOULD

BECOME TO WEAKEN SLOWLY TODAY BETWEEN A NORTHWESTERLY CONSTRAINT NOT

YET DEADLY, AND A PERSISTENT GOOD UPPER LEVEL DIVERGENCE POLARWARD.



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 BECOME REALLY UNFAVOURABLE UP TO 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.=