WTIO30 FMEE 211854



RSMC / TROPICAL CYCLONE CENTER / LA REUNION

TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)



0.A WARNING NUMBER: 43/8/20152016

1.A SEVERE TROPICAL STORM  8  (FANTALA)



2.A POSITION 2016/04/21 AT 1800 UTC:

WITHIN 20 NM RADIUS OF POINT 13.1 S / 56.8 E

(THIRTEEN    DECIMAL ONE   DEGREES SOUTH AND FIFTY SIX    DECIMAL

EIGHT   DEGREES EAST)

MOVEMENT : SOUTH-EAST 6 KT



3.A DVORAK ANALYSIS: 4.0/4.0/W 0.5/24 H



4.A CENTRAL PRESSURE: 985 HPA

5.A MAX AVERAGE WIND SPEED (10 MN): 60 KT

RADIUS OF MAXIMUM WINDS (RMW) :22 KM



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

28 KT NE: 90 SE: 70 SW: 60 NW: 90

34 KT NE: 60 SE: 60 SW: 55 NW: 70

48 KT NE: 40 SE: 40 SW: 40 NW: 50





7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1008 HPA / 300 KM

8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION : DEEP



1.B FORECASTS:

12H: 2016/04/22 06 UTC: 13.4 S / 56.9 E, MAX WIND=045 KT, MODERATE

TROPICAL STORM

24H: 2016/04/22 18 UTC: 13.6 S / 56.3 E, MAX WIND=040 KT, MODERATE

TROPICAL STORM

36H: 2016/04/23 06 UTC: 13.2 S / 55.0 E, MAX WIND=035 KT, MODERATE

TROPICAL STORM

48H: 2016/04/23 18 UTC: 12.7 S / 53.4 E, MAX WIND=035 KT, MODERATE

TROPICAL STORM

60H: 2016/04/24 06 UTC: 11.8 S / 51.7 E, MAX WIND=030 KT, TROPICAL

DEPRESSION

72H: 2016/04/24 18 UTC: 10.9 S / 50.1 E, MAX WIND=030 KT, TROPICAL

DEPRESSION



2.B LONGER-RANGE OUTLOOK :

96H: 2016/04/25 18 UTC: 9.9 S / 47.1 E, MAX WIND=025 KT, LOW

120H: 2016/04/26 18 UTC: 9.3 S / 44.4 E, MAX WIND=025 KT, LOW



2.C ADDITIONAL INFORMATION:

T=CI=4.0+



FANTALA IS QUITE RESISTANT SO FAR TO THE OBSERVED INCREASE OF THE

NORTH-EASTERLY WINDSHEAR DURING THE LAST 24 HOURS. THE CLOUD PATTERN

IS AN EMBEDDED CENTER WITH AT TIMES A WARM SPOT POPPING UP NEAR THE

ESTIMATED CENTER. MW IMAGERY REVEAL FAIRLY STRONG DEEP CONVECTIVE

ASYMMETRY WITHIN A STILL WELL DEFINED INNER-CORE. THE INTENSITY IS

UNCHANGED AND ARE IN THE LOW RANGE OF THE CURRENT AVAILABLE DVORAK

ESTIMATES. 1721Z ASCAT-A DATA CONFIRM A REALLY SMALL SIZE SYSTEM.



THE WIDE MID/UPPER TROPOPHERE MID-LATITUDE TROUGH, SOUTH OF SYSTEM IS

SHIFTING EASTWARD. BEHIND, THE ARRIVAL OF A HIGHT GEOPOTENTIAL CELL

IS EXPECTED TO BUILD A LOW/MID LEVEL SUBTROPICAL RIDGE OVER THE

BASIN. THIS PATTERN SHOULD GENERATE PROGRESSIVELY A SOUTHEASTWARD

STEERING FLOW. SO, FANTALA IS FORECASTED BEND SOUTHWARD AND THEN

ACCELERATE NORTHWESTWARD FRIDAY AND SATURDAY.

FOR THE FOLLOWING DAYS, THE SYSTEM IS LIKELY TO REMAIN STEERED BY

THIS HIGH SUBTROPICAL CELL IN THE LOW AND MID TROPOSPHERE, AND SHOULD

KEEP ON A NORTH-WESTWARD TRACK. FANTALA IS EXPECTED TO TRANSIT NORTH

OF MADAGASCAR SUNDAY. BUT THE MEMBERS OF THE ECMWF ENSEMBLE SHOW A

LATITUDE DISPERSION THAT SPREADS FROM FARQUHAR ISLAND TO MASOALA

PENINSULA IN THE NORTHEASTERN COASTS OF MADAGASCAR.



FANTALA IS CURRENTLY PASSING OVER AN OCEANIC AREA PREVIOUSLY COOLED

BY ITSELF SEVERAL DAYS AGO AND WITH A NEW FORECASTED SLOW DOWN, THE

LACK OF OCEANIC ENERGY SHOULD GRADUALLY WEAKEN THE SYSTEM. MOREOVER,

THE

ATMOSPHERIC CONDITIONS SHOULD BECOME LESS FAVORABLE WITH A WEAKENING

OF THE UPPER LEVEL DIVERGENCE ESPECIALLY EVEN ON THE POLAR SIDE, THE

INCREASE OF THE NORTHERLY SHEAR MORE SIGNIFICANTLY FROM SATURDAY WHEN

IT TURNS WESTERLY, VERY DRY MID-LEVEL AIR MASS SURROUNDING THE SYSTEM

FROM FRIDAY AND BEYOND, FANTALA'S ENVIRONMENT SHOULD LEAD TO A

SUSTAINED WEAKENING OVER THE PERIOD.=