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Direction Interrégionale de LA REUNION
B.P.4    97491 Ste Clotilde Cedex
Téléphone                02.62.92.11.00
Fax exploitation      02.62.92.11.48
Fax direction           02.62.92.11.47


RSMC / TROPICAL CYCLONE CENTRE / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)

0.A WARNING NUMBER : 5/11/20072008
1.A SEVERE TROPICAL STORM 11 (IVAN)

2.A POSITION 2008/02/08 AT 0600 UTC :
WITHIN 20 NM RADIUS OF POINT 15.4S / 63.2E
(FIFTEEN DECIMAL FOUR DEGREES SOUTH AND SIXTY THREE DECIMAL TWO DEGREES EAST)

3.A DVORAK ANALYSIS : 3.5/3.5 /D 0.5/18 H
4.A CENTRAL PRESSURE : 984 HPA
5.A MAX AVERAGE WIND SPEED (10 MN) : 50 KT

6.A EXTENSION OF WINDS BY QUADRANTS (KM):
30 KT NE: 150 SE: 120 SO: 180 NO: 150
50 KT NE: 050 SE: 050 SO: 050 NO: 050

7.A FIRST CLOSED ISOBARE (PRESSURE / AVERAGE DIAM): 1005 HPA / 800 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP

1.B FORECASTS:
12H: 2008/02/08 18 UTC: 15.8S/63.7E, MAX WIND=050KT, SEVERE TROP. STORM.
24H: 2008/02/09 06 UTC: 16.5S/63.6E, MAX WIND=055KT, SEVERE TROP. STORM.
36H: 2008/02/09 18 UTC: 16.8S/63.2E, MAX WIND=060KT, SEVERE TROP. STORM.
48H: 2008/02/10 06 UTC: 16.8S/62.8E, MAX WIND=060KT, SEVERE TROP. STORM.
60H: 2008/02/10 18 UTC: 16.6S/62.3E, MAX WIND=065KT, TROPICAL CYCLONE.
72H: 2008/02/11 06 UTC: 16.4S/61.6E, MAX WIND=070KT, TROPICAL CYCLONE.

2.B OTHER INFORMATIONS:
T=3.5, CI=3.5
UPPER LEVEL CONDITIONS HAS SLIGHTY IMPROVED WITH THE WEAKENESS OF THE NORTHERLY CONSTRAINTE.

SYSTEM IS UNDER THE STEERING INFLUENCE OF THE THICK NORTHWESTWARDS FLOW GENERATED BY THE MID-LEVEL EQUATORIAL RIDGE. THE SYSTEM SHOULD THEREFORE KEEP ON TRACKING SOUTHEASTWARDS FOR THE NEXT 12 HOURS. THEN, AS THE SUBTROPICAL RIDGE STRENGTHENS NEAR 70E AND A WEAKNESS IN THE SUBTROPICAL HIGH PRESSURES SHIFTS SOUTH OF THE SYSTEM, STEERING FLOW SHOULD BE WEAKER RESULTING IN A GRADUAL DECREASE OF THE SPEED AND IN A SOUTHWARDS TRACK, THEN MORE WEST SOUTHWESTWARDS VERY SLOWLY AS THE SUBTROPICAL RIDGE REBUILDS IN THE SOUTH-WEST.

IT IS IMPORTANT TO NOTE THAT THERE IS HIGH SPREAD IN NWP MODEL SOLUTION AT THIS TIME.