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
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RSMC / TROPICAL CYCLONE CENTRE / LA REUNION TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN) 0.A WARNING NUMBER : 7/11/20072008 1.A SEVERE TROPICAL STORM 11 (IVAN) 2.A POSITION 2008/02/08 AT 1800 UTC : WITHIN 20 NM RADIUS OF POINT 16.1S / 63.1E (SIXTEEN DECIMAL ONE DEGREES SOUTH AND SIXTY THREE DECIMAL ONE DEGREES EAST) 3.A DVORAK ANALYSIS : 4.0/4.0 /D 0.5/12 H 4.A CENTRAL PRESSURE : 975 HPA 5.A MAX AVERAGE WIND SPEED (10 MN) : 60 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): 1007 HPA / 1100 KM 8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP 1.B FORECASTS: 12H: 2008/02/09 06 UTC: 16.0S/63.0E, MAX WIND=065KT, TROPICAL CYCLONE. 24H: 2008/02/09 18 UTC: 15.9S/62.9E, MAX WIND=070KT, TROPICAL CYCLONE. 36H: 2008/02/10 06 UTC: 15.8S/62.8E, MAX WIND=065KT, TROPICAL CYCLONE. 48H: 2008/02/10 18 UTC: 15.6S/62.7E, MAX WIND=060KT, SEVERE TROP. STORM. 60H: 2008/02/11 06 UTC: 15.5S/62.6E, MAX WIND=060KT, SEVERE TROP. STORM. 72H: 2008/02/11 18 UTC: 15.3S/62.5E, MAX WIND=060KT, SEVERE TROP. STORM. 2.B OTHER INFORMATIONS: T=CI=4.0+ OVERALL STRUCTURE IMPROVES (SSMI 1447Z). HOWEVER, ON IR, CONVECTION DOES NOT CONSOLIDATE IN THE SOUTHEASTERN QUADRANT. AVAILABLE NWP MODELS ARE STILL NOT IN GOOD AGREEMENT WITH IVAN'S EVOLUTION. SOME (AS NOGAPS, ARPTROP) STILL DRIVE THE SYSTEM EASTWARDS UNDER THE STEERING INFLUENCE OF THE NEAR EQUATORIAL RIDGE. GIVEN THE CURRENT SOUTHWARDS MOTION SHIFTING AWAY THE SYSTEM FROM THIS WESTNORTHWESTWARDS STEERING, IT IS NOT THE SOLUTION REFLECTED BY THE FORECAST. AS SUGGESTED BY CEP, ALADIN AND UKMO, IVAN SHOULD BE IN A VERY WEAK STEERING FLOW AND SHOULD TRACK SLOWLIER (ERRATIC MOTION IS POSSIBLE). ON MONDAY, TRACK SHOULD TURN NORTHWESTWARDS AS THE SUBTROPICAL RIDGE SHOULD BUILD IN THE SOUTHWEST. IF ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE FOR FURTHER DEVELOPMENT, INTENSITY FLUCTUATIONS ARE STILL POSSIBLE IF THE SYSTEM REMAINS ALMOST-STATIONARY QUITE A LONG TIME. GIVEN THE WIDE SPREAD IN NWM SOLUTIONS, IT IS A LOWER THAN AVERAGE DEGREE OF CONFIDENCE IN THIS FORECAST.