WTIO30 FMEE 180627



RSMC / TROPICAL CYCLONE CENTER / LA REUNION

TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)



0.A WARNING NUMBER: 22/3/20172018

1.A SEVERE TROPICAL STORM  3  (BERGUITTA)



2.A POSITION 2018/01/18 AT 0600 UTC:

WITHIN 15 NM RADIUS OF POINT 20.7 S / 57.5 E

(TWENTY    DECIMAL SEVEN   DEGREES SOUTH AND FIFTY SEVEN    DECIMAL

FIVE   DEGREES EAST)

MOVEMENT : SOUTH-WEST 13 KT



3.A DVORAK ANALYSIS: 3.0/4.0/W 1.0/24 H



4.A CENTRAL PRESSURE: 980 HPA

5.A MAX AVERAGE WIND SPEED (10 MN): 55 KT

RADIUS OF MAXIMUM WINDS (RMW) :28 KM



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

28 KT NE: 150 SE: 560 SW: 520 NW: 190

34 KT NE: 110 SE: 130 SW: 130 NW: 90

48 KT NE:  SE: 70 SW: 70 NW:





7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1008 HPA / 1500 KM

8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION : DEEP



1.B FORECASTS:

12H: 2018/01/18 18 UTC: 22.4 S / 55.0 E, MAX WIND=050 KT, SEVERE

TROPICAL STORM

24H: 2018/01/19 06 UTC: 23.6 S / 53.2 E, MAX WIND=045 KT, MODERATE

TROPICAL STORM

36H: 2018/01/19 18 UTC: 25.6 S / 51.6 E, MAX WIND=045 KT, MODERATE

TROPICAL STORM

48H: 2018/01/20 06 UTC: 28.4 S / 50.5 E, MAX WIND=040 KT, MODERATE

TROPICAL STORM

60H: 2018/01/20 18 UTC: 31.4 S / 50.1 E, MAX WIND=040 KT, MODERATE

TROPICAL STORM

72H: 2018/01/21 06 UTC: 32.5 S / 50.7 E, MAX WIND=040 KT,

POST-TROPICAL DEPRESSION



2.B LONGER-RANGE OUTLOOK :

96H: 2018/01/22 06 UTC: 33.6 S / 54.3 E, MAX WIND=040 KT,

POST-TROPICAL DEPRESSION

120H: 2018/01/23 06 UTC: 36.1 S / 58.6 E, MAX WIND=040 KT,

POST-TROPICAL DEPRESSION



2.C ADDITIONAL INFORMATION:

T=3.0+ CI=4.0-



OVER THE PAST SIX HOURS, CONVECTIVE ACTIVITY MAINTAINED NEAR THE

CENTRE. HOWEVER THE CDO IS VERY SMALL. THIS MORNING SSMIS AND 0523Z

GMI

MICROWAVE SWATHS CONFIRMED THAT THE INNER CORE IS HARDLY REBUILDING

DESPITE THE ACCELERATION (SHEAR ANALYSED AT 15KT BY CIMSS). MAIN

ACTIVITY IS LOCATED IN THE PERIPHERAL BANDS. THE SYSTEM IS STILL

BENEFITING FROM A GOOD UPPER DIVERGENCE IN THE WESTERN CIRCLE. MSLP

WAS ESTIMATED WITH PLAISANCE OBSERVATIONS, AND THE POSITION WITH LA

REUNION RADAR DATA. THE CENTER PROBABLY PASSED A DOZEN KILOMETERS

OFFSHORE OF THE SOUTH-EASTERN COASTS OF MAURITIUS BETWEEN 00 AND 03Z.



THE SYSTEM IS NOW TRACKING SOUTHWESTWARD UNDER THE STEERING FLOW OF A

BUILDING MID-TROPOSPHERIC RIDGE LOCATED EAST. TODAY, BERGUITTA IS

FORECASTED TO KEEP ON ITS MOVEMENT, MOVING AWAY FROM MAURITIUS AND

PASSING AT LESS THAN 100KM FROM LA REUNION ISLAND SOUTH-EASTERN

COAST. IT WILL THEN CONTINUE TRACKING SOUTHWESTWARD BEFORE TRACKING

SOUTHWARDS. LATER, HIGH PRESSURE FURTHER SOUTH SHOULD SLOW DOWN THE

MOVING OF BERGUITTA, AND NEXT THE SYSTEM BERGUITTA SHOULD FOLLOW THE

MID-LATITUDE CIRCULATION.



THE SYSTEM IS UNDERGOING A MODERATE NORTHEASTERN VERICAL WINDSHEAR

OVER THE NORTHEASTERN EDGE OF THE AFOREMENTIONED RIDGE. INTENSITY

FORECAST CONTINUE TO FAVOUR A SLOW WEAKENING AS THE MAIN SCENARIO.

, WITH GOOD UPPER DIVERGENCE AND A RATHER FAST SPEED. FROM SATURDAY,

NORTHWESTWARD VERTICAL WINDSHEAR IS FORECASTED TO INCREASE AHEAD AN

UPPER LEVEL TROUGH. OCEANIC POTENTIAL WILL BECOME MARGINAL AT THIS

RANGE. BERGUITTA IS EXPECTED THEN TO START ITS EXTRATROPICALISATION

PHASE.



HOWEVER THE WEAKENING OF THE LAST 24 HOURS BERGUITTA REMAINS A

DANGEROUS SYSTEM WHICH IS FORECAST TO MOVE CLOSER TO REUNION ISLAND

AT A SIGNIFICANT INTENSITY. INHABITANTS ARE INVITED TO MONITOR

CLOSELY THE EVOLUTION OF THIS SYSTEM.=