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 : 10/4/20082009 1.A SEVERE TROPICAL STORM 4 (CINDA) 2.A POSITION 2008/12/18 AT 0600 UTC : 12.2S / 66.8E (TWELVE DECIMAL TWO DEGREES SOUTH AND SIXTY SIX DECIMAL EIGHT DEGREES EAST) MOVEMENT : SOUTH 5 KT 3.A DVORAK ANALYSIS : 3.5/3.5 /D 0.5/6 H 4.A CENTRAL PRESSURE : 985 HPA 5.A MAX AVERAGE WIND SPEED (10 MN) : 50 KT RADIUS OF MAXIMUM WINDS (RMW) : 20 KM 6.A EXTENSION OF WINDS BY QUADRANTS (KM): 30 KT NE: 090 SE: 150 SO: 150 NO: 090 50 KT NE: 040 SE: 040 SO: 040 NO: 040 7.A FIRST CLOSED ISOBARE (PRESSURE / AVERAGE DIAM): 1007 HPA / 700 KM 8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP 1.B FORECASTS: 12H: 2008/12/18 18 UTC: 13.2S/66.3E, MAX WIND=050KT, SEVERE TROP. STORM. 24H: 2008/12/19 06 UTC: 14.0S/65.4E, MAX WIND=040KT, MODERATE TROP. STORM. 36H: 2008/12/19 18 UTC: 14.3S/64.2E, MAX WIND=035KT, MODERATE TROP. STORM. 48H: 2008/12/20 06 UTC: 14.6S/63.0E, MAX WIND=030KT, TROP. DEPRESSION. 60H: 2008/12/20 18 UTC: 15.2S/61.8E, MAX WIND=030KT, TROP. DEPRESSION. 72H: 2008/12/21 06 UTC: 15.8S/61.0E, MAX WIND=030KT, TROP. DEPRESSION. 2.B OTHER INFORMATIONS: SATELLITE IMAGERY ANALYSIS LEADS TO T=CI=3.5+. HOWEVER 85 GHZ MICROWAVE AND IR /VIS IMAGERY ARE MUCH MORE IMPRESSIVE THAN 37 GHZ MICROWAVE IMAGERY. 85 GHZ IMAGERY (F17/0052Z, F15/0156Z, F16/0325Z) ACTUALLY DISPLAYS A RATHER WELL DEFINED EYE, BUT ON THE 37 GHZ THIS EYE IS ERODED ON THE NORTHERN EDGE. MOREOVER THESE IMAGERIES SHOW A TILT BETWEEN THE LOW LEVEL AND THE UPPER LEVEL CENTRE. THIS SHOWS THE SYSTEM IS UNDERGOING A NORTHERLY CONSTRAINT. THE ENVIRONMENT REMAINS HOWEVER SLIGHTLY FAVOURABLE. LOCATED BENEATH THE WESTERN PERIPHERY OF THE UPPER LEVEL RIDGE, THE SYSTEM BENEFITS FROM STILL RATHER WEAK VERTICAL WINDSHEAR, WHILE THE UPPER OUTFLOW IS RESTRICTED TO A MODERATELY POTENT POLEWARD CHANNEL (AHEAD OF AN UPPER TROUGH TO THE WEST). THIS ENVIRONMENT IS STILL FORECAST TO BECOME LESS AND LESS FAVORABLE WITH THE STRENGTHENING OF NORTHERN TO NORTHWESTERN WINDS AND THE LOSS OF THE UPPER LEVEL RIDGE. ABOUT THE FORCAST TRACK, IT SEEMS THAT CURRENT STEERING FLOW ARE FROM THE MID-LEVEL (700/500 HPA)- WHERE THEY ARE SOMEWHAT WEAK - AS THE SYSTEM IS LOCATED ON THE WESTERN EDGE OF A MID LEVEL RIDGE (THIS EXPLAINS THE CURRENT SOUTHWARDS MOTION). AS THE SYSTEM SHOULD GRADUALLY WEAKEN, IT SHOULD BE STEERED BY A MORE LOW LEVEL STEERING FLOW AND THEN TRACK WESTSOUTHWESTWARDS.