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 : 6/4/20082009 1.A TROPICAL DEPRESSION 4 2.A POSITION 2008/12/17 AT 0600 UTC : WITHIN 20 NM RADIUS OF POINT 10.3S / 66.5E (TEN DECIMAL THREE DEGREES SOUTH AND SIXTY SIX DECIMAL FIVE DEGREES EAST) MOVEMENT : WEST-SOUTH-WEST 4 KT 3.A DVORAK ANALYSIS : 2.5/2.5 /D 0.5/24 H 4.A CENTRAL PRESSURE : 998 HPA 5.A MAX AVERAGE WIND SPEED (10 MN) : 30 KT RADIUS OF MAXIMUM WINDS (RMW) : 30 KM 6.A EXTENSION OF WINDS BY QUADRANTS (KM): 30 KT NE: 040 SE: 080 SO: 080 NO: 040 7.A FIRST CLOSED ISOBARE (PRESSURE / AVERAGE DIAM): 1009 HPA / 900 KM 8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: MEDIUM 1.B FORECASTS: 12H: 2008/12/17 18 UTC: 11.0S/65.6E, MAX WIND=030KT, TROP. DEPRESSION. 24H: 2008/12/18 06 UTC: 12.0S/64.5E, MAX WIND=035KT, MODERATE TROP. STORM. 36H: 2008/12/18 18 UTC: 12.8S/63.5E, MAX WIND=035KT, MODERATE TROP. STORM. 48H: 2008/12/19 06 UTC: 13.4S/62.2E, MAX WIND=030KT, TROP. DEPRESSION. 60H: 2008/12/19 18 UTC: 13.8S/61.0E, MAX WIND=030KT, TROP. DEPRESSION. 72H: 2008/12/20 06 UTC: 14.2S/60.0E, MAX WIND=030KT, TROP. DEPRESSION. 2.B OTHER INFORMATIONS: T=CI=2.5. THE DEEP CONVECTION HAS NOW PERSISTED FOR MORE THAN 12H ABOVE THE LOW LEVEL CIRCULATION CENTRE ENABLING THE SYSTEM TO INTENSIFY TO TROPICAL DEPRESSION STAGE. THIS SYSTEM EVOLVES WITHIN A NEUTRAL TO SLIGHTLY FAVOURABLE ENVIRONMENT. LOCATED BENEATH THE WESTERN PERIPHERY OF THE UPPER RIDGE IT BENEFITS FROM WEAK VERTICAL WINDSHEAR, BUT UPPER OUTFLOW IS RESTRICTED TO A RATHER WEAK POLEWARD CHANNEL. THE SYSTEM IS EXPECTED TO KEEPS ON TRACKING WESTSOUTHWESTWARDS TO SOUTHWESTWARDS. THERE IS HOWEVER SOME DESAGREEMENT BETWEEN THE DIFFERENT NUMERICAL MODELS ABOUT THE SPEED OF MOVEMENT. THE POTENTIAL FOR FURTHER INTENSIFICATION APPEARS LIMITED ALTHOUGH THERE IS A WINDOW FOR SOME IMPROVEMENT WITHIN THE NEXT 24 HOURS BEFORE MODERATE NORTHERLY SHEAR SETTLES AHEAD OF AN UPPER LEVEL TROUGH WEST OF THE SYSTEM AND STARTS TO IMPINGE ON THE SYSTEM. SYSTEM COULD HOWEVER REACH TEMPORARILY THE MINIMAL TROPICAL STORM STAGE.