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 : 2/11/20072008 1.A MODERATE TROPICAL STORM 11 (IVAN) 2.A POSITION 2008/02/07 AT 1200 UTC : 13.9S / 61.3E (THIRTEEN DECIMAL NINE DEGREES SOUTH AND SIXTY ONE DECIMAL THREE DEGREES EAST) 3.A DVORAK ANALYSIS : 3.0/3.0 /D 0.5/12 H 4.A CENTRAL PRESSURE : 990 HPA 5.A MAX AVERAGE WIND SPEED (10 MN) : 40 KT 6.A EXTENSION OF WINDS BY QUADRANTS (KM): 30 KT NE: 250 SE: 180 SO: 100 NO: 150 7.A FIRST CLOSED ISOBARE (PRESSURE / AVERAGE DIAM): 1009 HPA / 1000 KM 8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: MEDIUM 1.B FORECASTS: 12H: 2008/02/08 00 UTC: 14.6S/63.0E, MAX WIND=050KT, SEVERE TROP. STORM. 24H: 2008/02/08 12 UTC: 15.7S/64.2E, MAX WIND=060KT, SEVERE TROP. STORM. 36H: 2008/02/09 00 UTC: 16.6S/64.7E, MAX WIND=060KT, SEVERE TROP. STORM. 48H: 2008/02/09 12 UTC: 17.2S/64.7E, MAX WIND=060KT, SEVERE TROP. STORM. 60H: 2008/02/10 00 UTC: 17.7S/64.4E, MAX WIND=060KT, SEVERE TROP. STORM. 72H: 2008/02/10 12 UTC: 18.0S/63.7E, MAX WIND=060KT, SEVERE TROP. STORM. 2.B OTHER INFORMATIONS: T=CI=3.0 UPPER LEVEL CONDITIONS HAS IMPROVED AS A CUT-OFF LOW SHIFTS SOUTH OF THE SYSTEM AND THEREFORE ENHANCES POLEWARDS UPPER LEVEL DIVERGENCE. SYSTEM IS UNDER THE STEERING INFLUENCE OF THE THICK WEST-NORTHWESTWARDS FLOW GENERATED BY THE MID-LEVEL EQUATORIAL RIDGE. THE SYSTEM SHOULD THEREFORE KEEP ON TRACKING EAST-SOUTHEASTWARDS FOR THE NEXT 24 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. AVAILABLE NWP ARE NOT IN GOOD AGREEMENT. US AND ARPEGE MODELS DO NOT DEEP THE SYSTEM AND TRACK GLOBALLY EASTWARDS. THE FORECAST IS CLOSE TO ECMWF MODEL SCENARIO, AS THIS MODEL PROPERLY ANALYZES THE SYSTEM IN LOCATION AND INTENSITY.