WTIO30 FMEE 131915



RSMC / TROPICAL CYCLONE CENTER / LA REUNION

TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)



0.A WARNING NUMBER: 17/5/20142015

1.A INTENSE TROPICAL CYCLONE  5  (BANSI)



2.A POSITION 2015/01/13 AT 1800 UTC:

WITHIN 20 NM RADIUS OF POINT 17.4 S / 58.2 E

(SEVENTEEN    DECIMAL FOUR   DEGREES SOUTH AND FIFTY EIGHT    DECIMAL

TWO   DEGREES EAST)

MOVEMENT : EAST-SOUTH-EAST 3 KT



3.A DVORAK ANALYSIS: 4.5/5.5/W 2.0/24 H



4.A CENTRAL PRESSURE: 953 HPA

5.A MAX AVERAGE WIND SPEED (10 MN): 90 KT

RADIUS OF MAXIMUM WINDS (RMW) :13 KM



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

28 KT NE: 410 SE: 740 SW: 310 NW: 370

34 KT NE: 230 SE: 190 SW: 200 NW: 220

48 KT NE: 90 SE: 90 SW: 90 NW: 90

64 KT NE: 50 SE: 50 SW: 50 NW: 50



7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1009 HPA / 1600 KM

8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION : DEEP



1.B FORECASTS:

12H: 2015/01/14 06 UTC: 17.8 S / 58.8 E, MAX WIND=080 KT, TROPICAL

CYCLONE

24H: 2015/01/14 18 UTC: 18.4 S / 59.6 E, MAX WIND=090 KT, INTENSE

TROPICAL CYCLONE

36H: 2015/01/15 06 UTC: 19.0 S / 60.4 E, MAX WIND=090 KT, INTENSE

TROPICAL CYCLONE

48H: 2015/01/15 18 UTC: 20.1 S / 62.1 E, MAX WIND=085 KT, TROPICAL

CYCLONE

60H: 2015/01/16 06 UTC: 21.8 S / 63.6 E, MAX WIND=085 KT, TROPICAL

CYCLONE

72H: 2015/01/16 18 UTC: 23.7 S / 65.0 E, MAX WIND=080 KT, TROPICAL

CYCLONE



2.B LONGER-RANGE OUTLOOK :

96H: 2015/01/17 18 UTC: 26.8 S / 69.5 E, MAX WIND=075 KT,

POST-TROPICAL DEPRESSION

120H: 2015/01/18 18 UTC: 28.7 S / 76.9 E, MAX WIND=055 KT,

POST-TROPICAL DEPRESSION



2.C ADDITIONAL INFORMATIONS:

T=4.5 CI=5.5.



THE EYE OF BANSI HAS DISAPPEARED JUST AFTER 12Z THIS AFTERNOON. MW

IMAGERY SHOW THAT THE SYSTEM IS UNDERGOING AN ERC AND IS IN THE

WEAKENING PHASE AS THE INNER CORE IS COLLAPSING WITH A BUILDING OUTER

EYEWALL. THE CURRENT POSITION IS BASED ON A FAIR METOP AND ASCAT-A

FIX AT 1721Z. THE CURRENT INTENSITY ESTIMATE HOLD THE SYSTEM AS A

MINIMAL INTENSE CYCLONE ALTHOUGH THIS COULD BE GENEROUS GIVEN THE

ERC. SATCON OF 1237Z IS AT 94 KT (1 MIN WINDS).



TOMOROW, THE MID-LEVEL RIDGE SHIFTS BACK IN THE EAST OF THE SYSTEM

AND A COL BUILDS IN ITS SOUTH. BANSI IS THEREFORE EXPECTED TO

GRADUALLY ACCELERATING SOUTH-EASTWARDS UNTIL SATURDAY. THE CURRENT

TRACK FORECAST TAKES INTO ACCOUNT THE VERY LATEST GUIDANCE FROM THE

12Z CYCLE (INCLUDING THE EURO MODEL)



ON THIS FORECAST TRACK, ENVIRONMENTAL CONDITIONS ARE VERY FAVOURABLE

ON TODAY AND WEDNESDAY UNDER THE UPPER LEVEL RIDGE AXIS AS AT LEAST 2

UPPER LEVEL CHANNELS EQUATOR-WARD AND POLEWARD TAKE PLACE WITHIN THE

PERIOD. THE CURRENT INTENSITY FORECAST IS LOWER THAN THE PREVIOUS ONE

BUT BANSI IS EXPECTED TO BECOME A VERY LARGE TROPICAL CYCLONE.



THURSDAY, BANSI IS LIKELY TO SHIFT SOUTH OF THE UPPER LEVEL RIDGE

AXIS AND KEEPS ONLY ITS POLEWARD OUTFLOW CHANNEL AND AN UPPER LEVEL

TROUGH SHOULD GETTING CLOSER FROM ITS SOUTHWEST. THEREFORE, VERTICAL

WINDSHEAR SHOULD INCREASE FROM THURSDAY EVENING.



ON FRIDAY, BANSI IS LIKELY TO BEGIN TO WEAKEN OWING TO WESTERLY

VERTICAL WINDSHEAR AND THE LOWERING OCEANIC HEAT CONTENT.



DUE TO THE EXPECTED STRONG WINDS EXTENSION (AFTER THE ERC), BANSI

WILL REMAIN AN EXTREMELY DANGEROUS SYSTEM. THEREFORE, THE INHABITANTS

OF MAURITIUS AND SPECIALLY RODRIQUES ISLANDS (INCREASING THREAT WITH

SEVERE WEATHER CONDITIONS EXPECTED THURSDAY) SHOULD CLOSELY MONITOR

THE PROGRESS OF THIS DANGEROUS SYSTEM WITHIN THE NEXT DAYS.=