WTIO30 FMEE 120620



RSMC / TROPICAL CYCLONE CENTER / LA REUNION

TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)



0.A WARNING NUMBER: 5/8/20152016

1.A MODERATE TROPICAL STORM  8  (FANTALA)



2.A POSITION 2016/04/12 AT 0600 UTC:

WITHIN 20 NM RADIUS OF POINT 13.3 S / 69.8 E

(THIRTEEN    DECIMAL THREE   DEGREES SOUTH AND SIXTY NINE    DECIMAL

EIGHT   DEGREES EAST)

MOVEMENT : WEST 6 KT



3.A DVORAK ANALYSIS: 3.5/3.5/D 0.5/6 H



4.A CENTRAL PRESSURE: 994 HPA

5.A MAX AVERAGE WIND SPEED (10 MN): 45 KT

RADIUS OF MAXIMUM WINDS (RMW) :56 KM



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

28 KT NE: 90 SE: 190 SW: 200 NW: 90

34 KT NE: 60 SE: 90 SW: 90 NW: 60







7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1010 HPA / 400 KM

8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION : DEEP



1.B FORECASTS:

12H: 2016/04/12 18 UTC: 13.3 S / 68.5 E, MAX WIND=055 KT, SEVERE

TROPICAL STORM

24H: 2016/04/13 06 UTC: 13.2 S / 67.3 E, MAX WIND=065 KT, TROPICAL

CYCLONE

36H: 2016/04/13 18 UTC: 13.1 S / 66.0 E, MAX WIND=065 KT, TROPICAL

CYCLONE

48H: 2016/04/14 06 UTC: 12.8 S / 64.6 E, MAX WIND=075 KT, TROPICAL

CYCLONE

60H: 2016/04/14 18 UTC: 12.5 S / 62.9 E, MAX WIND=080 KT, TROPICAL

CYCLONE

72H: 2016/04/15 06 UTC: 12.3 S / 61.3 E, MAX WIND=085 KT, TROPICAL

CYCLONE



2.B LONGER-RANGE OUTLOOK :

96H: 2016/04/16 06 UTC: 12.2 S / 59.0 E, MAX WIND=080 KT, TROPICAL

CYCLONE

120H: 2016/04/17 06 UTC: 11.7 S / 57.6 E, MAX WIND=070 KT, TROPICAL

CYCLONE



2.C ADDITIONAL INFORMATION:

T=CI=3.5-



OVER THE LAST 6 HOURS, THE SYSTEM HAS CONTINUED TO INTENSIFY. FANTALA

CLOUD PATTERN IS MORE SYMETRIC THANKS TO THE DECAY OF THE EASTERLY

CONSTRAINT. UPPER LEVEL DIVERGENCE REMAINS VERY GOOD AND THE LAST

VISIBLE IMAGERY SHOWS THE BEGINNING OF AN EYE FORMATION.



THE SYSTEM IS MOVING WESTWARD OVER THE NORTHERN EDGE OF THE LOW TO

MID LEVEL HIGHS LOCATED TO ITS SOUTH AND SOUTH-WEST. WITHIN THE NEXT

DAYS, THE MID LEVEL CIRCULATION SHOULD BECOME PROGRESSIVELY MORE

MERIDIAN WITH  HIGHS WHICH SHOULD INCREASE IN THE SOUTH-WEST OF THE

SYSTEM AND THE ARRIVAL OF AN UPPER/MID TROUGH EAST OF 70E. IN

RESPONSE, FANTALA SHOULD SLOW DOWN FROM THIS WEEK-END PUSHING AGAINST

THE RIDGE AND ORIENTATE ITS TRACK SOUTEASTWARD TOWARD THE MID/UPPER

TROUGH.

BUT, FOR NOW THIS TRAJECTORY CHANGE IS STILL UNCERTAIN, AS DESCRIBED

BY THE LAST ECMWF EPS. SOME MEMBERS LIKE THE DETERMINISTIC DELAY THIS

COMEBACK, WHILE THE MAJORITY (FASTER MEMBERS MOSTLY) SUGGEST THE

CONTINUATION OF THE ZONAL TRACK. THE PRESENT FORECAST IS AN

INTERMEDIATE SCENARIO IN TERMS OF SPEED, CLOSE TO THE ECMWF

DETERMINISTIC.



FANTALA IS FORESCASTED TO TRACKING BENEATH THE SUBTOPICAL RIDGE AND

BENEFIT FROM A WEAK VERTICAL WIND SHEAR. SATURDAY, THE UPPER LEVEL

DIVERGENCE SHOULD BECOME MARGINAL EQUATORWARDS (BUT STILL GOOD TO THE

SOUTH) AND A NORTHWESTERLY CONSTRAINT IS EVEN POSSIBLE. COMBINED WITH

A POTENTIAL SELF INDUCED COOLING OF THE SST DUE TO THE SLOW FORWARD

MOTION, AT LEAST A TEMPORARY WEAKENING TREND IS POSSIBLE NEAR THE END

OF THE FORECAST PERIOD.=