WTIO30 FMEE 140017



RSMC / TROPICAL CYCLONE CENTER / LA REUNION

TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)



0.A WARNING NUMBER: 5/3/20172018

1.A MODERATE TROPICAL STORM  3  (BERGUITTA)



2.A POSITION 2018/01/14 AT 0000 UTC:

WITHIN 25 NM RADIUS OF POINT 18.2 S / 63.2 E

(EIGHTEEN    DECIMAL TWO   DEGREES SOUTH AND SIXTY THREE    DECIMAL

TWO   DEGREES EAST)

MOVEMENT : WEST 5 KT



3.A DVORAK ANALYSIS: 3.0/3.0/D 0.5/6 H



4.A CENTRAL PRESSURE: 995 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: 160 SE: 190 SW: 230 NW: 100

34 KT NE: 110 SE: 120 SW: 140 NW: 70







7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1004 HPA / 800 KM

8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION : MEDIUM



1.B FORECASTS:

12H: 2018/01/14 12 UTC: 18.1 S / 62.2 E, MAX WIND=045 KT, MODERATE

TROPICAL STORM

24H: 2018/01/15 00 UTC: 17.7 S / 61.6 E, MAX WIND=055 KT, SEVERE

TROPICAL STORM

36H: 2018/01/15 12 UTC: 17.3 S / 61.1 E, MAX WIND=065 KT, TROPICAL

CYCLONE

48H: 2018/01/16 00 UTC: 16.9 S / 60.5 E, MAX WIND=075 KT, TROPICAL

CYCLONE

60H: 2018/01/16 12 UTC: 16.8 S / 60.0 E, MAX WIND=080 KT, TROPICAL

CYCLONE

72H: 2018/01/17 00 UTC: 16.9 S / 59.3 E, MAX WIND=085 KT, TROPICAL

CYCLONE



2.B LONGER-RANGE OUTLOOK :

96H: 2018/01/18 00 UTC: 18.4 S / 57.5 E, MAX WIND=095 KT, INTENSE

TROPICAL CYCLONE

120H: 2018/01/19 00 UTC: 20.6 S / 55.3 E, MAX WIND=095 KT, INTENSE

TROPICAL CYCLONE



2.C ADDITIONAL INFORMATION:

T=CI=3.0+



DURING THE LAST 6 HOURS, SEVERAL CONVECTIVE BURSTS WRAPPED VERY

CLOSELY AROUND THE CIRCULATION CENTER. THIS CORRESPONDS TO AN

IMPROVEMENT OF THE CLOUD PATTERN. 2022Z AMSR2 AND 1956Z GMI MW IMAGES

ALSO SHOW A CLEAR CONSOLIDATION OF THE LOW/MID LEVEL CORE STRUCTURE

COMPARED TO PREVIOUS DATA.



THE SYSTEM SEEMS TO SLIGHTLY TURN WESTWARD CURRENTLY, AS IT BUMPS

INTO A STRONG RIDGE BUILDING UP FROM THE SOUTH OF MADAGASCAR.

AVAILABLE MODEL GUIDANCE SUGGEST A NORTHWESTWARD TURN ON THE

NORTHEASTERN SIDE OF THE RIDGE BUT WITH STILL VERY DIFFERENT TRACK

SPEEDS. THIS MAINTAINS A HIGH UNCERTAINTY ON THE TRACK FORECAST, AS

ALSO ILLUSTRATED BY THE STRONG DISPERSION OF THE ENSEMBLE FORECAST.

WEDNESDAY, A BEND TOWARD THE SOUTHWEST LINKED TO THE SHIFT OF THE

RIDGE AND THE ARRIVAL OF A MID/UPPER LEVEL TROUGH SOUTH OF MADAGASCAR

IS FORECAST WITH BETTER CONFIDENCE. BUT THE LOW PREVISIBILITY DURING

THE FIRST DAYS INDUCES AN UNCERTAINTY OVER THE TIMING OF THE

POTENTIAL THREAT OVER MASCARENES ISLANDS. THIS ADVISORY IS BASED ON A

MEAN SCENARIO BETWEEN THE AMERICAN AND EUROPEAN MODELS.



THE SYSTEM IS EXPECTED TO GRADUALLY INTENSIFY WITHIN VERY GOOD

ENVIRONMENTAL CONDITIONS. BERGUITTA SHOULD TRACK UNDER THE UPPER

LEVEL RIDGE, THUS WITH LOW VERTICAL WIND WINDSHEAR. IN THE SHORT

TERM, UPPER LEVEL DIVERGENCE SHOULD IMPROVE WITH BOTH POLEWARD AND

EQUATORWARD OUTFLOW CHANNELS.



NEXT WEEK, A MATURE SYSTEM SHOULD TRACK IN THE VICINITY OF MASCARENES

ISLANDS. INHABITANTS ARE INVITED TO MONITOR THE EVOLUTION OF THIS

SYSTEM IN THE NEXT DAYS.=