WTIO30 FMEE 111845



RSMC / TROPICAL CYCLONE CENTER / LA REUNION

TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)



0.A WARNING NUMBER: 29/13/20142015

1.A TROPICAL CYCLONE  13  (JOALANE)



2.A POSITION 2015/04/11 AT 1800 UTC:

WITHIN 30 NM RADIUS OF POINT 23.0 S / 68.1 E

(TWENTY THREE    DECIMAL ZERO   DEGREES SOUTH AND SIXTY EIGHT

DECIMAL ONE   DEGREES EAST)

MOVEMENT : SOUTH-SOUTH-EAST 12 KT



3.A DVORAK ANALYSIS: 4.0/4.5/W 0.5/12 H



4.A CENTRAL PRESSURE: 973 HPA

5.A MAX AVERAGE WIND SPEED (10 MN): 65 KT

RADIUS OF MAXIMUM WINDS (RMW) :65 KM



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

28 KT NE: 330 SE: 350 SW: 480 NW: 260

34 KT NE: 240 SE: 280 SW: 390 NW: 230

48 KT NE: 160 SE: 180 SW: 210 NW: 150

64 KT NE: 70 SE: 70 SW: 70 NW: 70



7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1008 HPA / 700 KM

8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION : MEDIUM



1.B FORECASTS:

12H: 2015/04/12 06 UTC: 25.4 S / 67.9 E, MAX WIND=060 KT,

POST-TROPICAL DEPRESSION

24H: 2015/04/12 18 UTC: 27.1 S / 67.0 E, MAX WIND=055 KT,

POST-TROPICAL DEPRESSION

36H: 2015/04/13 06 UTC: 28.4 S / 66.0 E, MAX WIND=055 KT,

POST-TROPICAL DEPRESSION

48H: 2015/04/13 18 UTC: 30.0 S / 66.5 E, MAX WIND=055 KT,

POST-TROPICAL DEPRESSION

60H: 2015/04/14 06 UTC: 32.2 S / 68.2 E, MAX WIND=060 KT,

EXTRATROPICAL SYSTEM

72H: 2015/04/14 18 UTC: 33.9 S / 69.9 E, MAX WIND=050 KT,

EXTRATROPICAL SYSTEM



2.B LONGER-RANGE OUTLOOK :

96H: 2015/04/15 18 UTC: 35.3 S / 72.7 E, MAX WIND=040 KT,

EXTRATROPICAL SYSTEM

120H: 2015/04/16 18 UTC: 35.3 S / 76.0 E, MAX WIND=030 KT,

EXTRATROPICAL SYSTEM



2.C ADDITIONAL INFORMATIONS:

T=4.0 AND CI=4.5-

SUCCESSIVE AMSU-A CROSS-SECTIONS N15 AT 0041Z AND N19 AT 0946Z REVEAL

THAT JOALANE'S WARM CORE ANOMALY IS PROGRESSIVELY ELONGATING

DOWNWARDS.

INTERACTING WITH THE WESTERLY SUBTROPICAL JET AND OVER MARGINAL

OCEANIC HEAT CONTENT (SST AT ABOUT 25/26 DG), SYSTEM BEGINS TO EVOLVE

ONTO AN HYBRID POST-TROPICAL STRUCTURE.

THIS STRUCTURE CHANGE GENERATES A DILATATION OF THE RADIUS OF MAXIMUM

WINDS (35/40 NM ON SSMIS-F19 1423Z SWATH).



WITHIN A MORE AND MORE BAROCLINIC ENVIRONMENT, JOALANE IS EXPECTED TO

KEEP ON LOSING ITS PURELY TROPICAL CHARACTERISTICS BUT THE SYSTEM IS

HOWEVER EXPECTED TO REMAIN POWERFUL AS STORM FORCE WINDS SHOULD LAST

FOR SEVERAL DAYS.

THE END OF THE EXTRATROP PROCESS IS ONLY FORECAST FROM THURSDAY 14 AS

THE SYSTEM SHOULD GRADUALLY BE EMBEDDED WITHIN THE MID-LAT

WESTERLIES.



BEFORE THAT TIME, THE POLEWARDS TRACK OF JOALANE WILL BE TEMPORARILY

LIMITED ON MONDAY BY A BUILDING BUT TRANSIENT SUBTROPICAL RIDGE.=