WTIO30 FMEE 091308



RSMC / TROPICAL CYCLONE CENTER / LA REUNION

TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)



0.A WARNING NUMBER: 20/13/20142015

1.A SEVERE TROPICAL STORM  13  (JOALANE)



2.A POSITION 2015/04/09 AT 1200 UTC:

WITHIN 20 NM RADIUS OF POINT 17.0 S / 65.7 E

(SEVENTEEN    DECIMAL ZERO   DEGREES SOUTH AND SIXTY FIVE    DECIMAL

SEVEN   DEGREES EAST)

MOVEMENT : SOUTH 5 KT



3.A DVORAK ANALYSIS: 4.0/4.0/W 0.5/24 H



4.A CENTRAL PRESSURE: 979 HPA

5.A MAX AVERAGE WIND SPEED (10 MN): 60 KT

RADIUS OF MAXIMUM WINDS (RMW) :24 KM



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

28 KT NE: 330 SE: 500 SW: 280 NW: 260

34 KT NE: 190 SE: 280 SW: 240 NW: 150

48 KT NE: 70 SE: 90 SW: 70 NW: 60





7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1006 HPA / 1100 KM

8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION : DEEP



1.B FORECASTS:

12H: 2015/04/10 00 UTC: 18.3 S / 66.2 E, MAX WIND=070 KT, TROPICAL

CYCLONE

24H: 2015/04/10 12 UTC: 19.7 S / 67.5 E, MAX WIND=080 KT, TROPICAL

CYCLONE

36H: 2015/04/11 00 UTC: 21.4 S / 68.7 E, MAX WIND=070 KT, TROPICAL

CYCLONE

48H: 2015/04/11 12 UTC: 23.4 S / 69.4 E, MAX WIND=060 KT, SEVERE

TROPICAL STORM

60H: 2015/04/12 00 UTC: 25.7 S / 69.5 E, MAX WIND=055 KT,

POST-TROPICAL DEPRESSION

72H: 2015/04/12 12 UTC: 27.7 S / 69.3 E, MAX WIND=050 KT,

POST-TROPICAL DEPRESSION



2.B LONGER-RANGE OUTLOOK :

96H: 2015/04/13 12 UTC: 29.6 S / 68.4 E, MAX WIND=045 KT,

POST-TROPICAL DEPRESSION

120H: 2015/04/14 12 UTC: 32.2 S / 72.6 E, MAX WIND=045 KT,

POST-TROPICAL DEPRESSION



2.C ADDITIONAL INFORMATIONS:

T=4.0 AND CI=4.0



DURING THE LAST 6 HOURS, THE CLOUD PATTERN AND THE INNER CORE

STRUCTURE HAS CHANGED LITTLE ACCORDING TO CLASSICAL SATELLITE IMAGERY

(DESPITE A SLIGHT IMPROVEMENT SEEN ON VIS IMAGERY THIS AFTERNOON) AND

MICRO-WAVE IMAGERY (CF. SSMI AT 1039Z). RUNNING 3H MEAN DT IS AT 4.0

(MORE OR LESS) SINCE ALMOST 22Z ... SO THE CURRENT INTENSITY IS NOW

PUT AT 4.0 ... 60 KT 10 MIN WINDS.



JOALANE IS STRUGGLING TO INTENSIFY AND AS THE REASON OF THIS

INTENSITY FLUCTUATIONS ARE NOT WELL UNDERSTOOD, IT PUTS STRONG

UNCERTAINTY OVER THE EXPECTED RE-INTENSIFICATION SHOWN ON THE

OFFICIAL TRACK. TO THE SLIGHT NORTHERLY CONSTRAINT (ANALYZED BY THE

CIMSS) AND MENTIONED PREVIOUSLY, ONE MAY ADD THE NEGATIVE FEED-BACK

OF THE SST AS JOALANE HAS COME-BACK, THIS MORNING, OVER ITS LOCATION

THREE DAYS AGO.



AS JOALANE IS NOW EXPECTED TO MOVE AWAY OF THIS AREA AND ATMOSPHERIC

CONDITIONS ARE EXPECTED TO REMAIN FAVORABLE, JOALANE HAS STILL THE

POTENTIAL TO RE-INTENSIFY UP TO FRIDAY EVENING OR SATURDAY MORNING.

AFTER THAT TIME, IT SHOULD WEAKEN CLEARLY, UNDER THE NEGATIVE EFFECT

OF BOTH STRENGTHENING VWS AND LOWERING OF THE OHC.



JOALANE IS CURRENTLY MOVING SOUTH-SOUTH-EASTWARD TOWARDS A BAROMETRIC

COL AND UNDER THE STEERING INFLUENCE OF A MID-TROPOSPHERIC RIDGE IN

ITS EAST. AT THE END OF THE FORECAST PERIOD, IT COULD SLOW UNDER THE

INFLUENCE OF A RIDGE IN ITS SOUTH-WEST.



THERE IS A GOOD CONSENSUS ABOUT THIS TRACK AMONG THE LAST AVAILABLE

NWP MODELS.=