Direction Interrégionale de LA REUNION
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RSMC / TROPICAL CYCLONE CENTRE / LA REUNION TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN) 0.A WARNING NUMBER : 18/4/20082009 1.A MODERATE TROPICAL STORM 4 (CINDA) 2.A POSITION 2008/12/20 AT 0600 UTC : WITHIN 20 NM RADIUS OF POINT 13.8S / 62.9E (THIRTEEN DECIMAL EIGHT DEGREES SOUTH AND SIXTY TWO DECIMAL NINE DEGREES EAST) MOVEMENT : WEST 7 KT 3.A DVORAK ANALYSIS : 2.5/3.0 /W 0.5/6 H 4.A CENTRAL PRESSURE : 992 HPA 5.A MAX AVERAGE WIND SPEED (10 MN) : 40 KT RADIUS OF MAXIMUM WINDS (RMW) : NIL 6.A EXTENSION OF WINDS BY QUADRANTS (KM): 30 KT NE: 060 SE: 200 SO: 200 NO: 060 7.A FIRST CLOSED ISOBARE (PRESSURE / AVERAGE DIAM): 1010 HPA / 800 KM 8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: MEDIUM 1.B FORECASTS: 12H: 2008/12/20 18 UTC: 14.8S/61.4E, MAX WIND=035KT, MODERATE TROP. STORM. 24H: 2008/12/21 06 UTC: 15.6S/60.2E, MAX WIND=035KT, MODERATE TROP. STORM. 36H: 2008/12/21 18 UTC: 16.1S/59.8E, MAX WIND=035KT, MODERATE TROP. STORM. 48H: 2008/12/22 06 UTC: 16.6S/59.8E, MAX WIND=030KT, TROP. DEPRESSION. 60H: 2008/12/22 18 UTC: 17.1S/59.7E, MAX WIND=030KT, TROP. DEPRESSION. 72H: 2008/12/23 06 UTC: 17.1S/59.7E, MAX WIND=030KT, TROP. DEPRESSION. 2.B OTHER INFORMATIONS: T=2.5 CI=3.0 CINDA SHOWS A SHEAR PATTERN. ON THE VERY LAST VISIBLE IMAGERY, THE LLCC APPEAR CLEARLY AT ABOUT 45/50 NM NORTH OF THE MAIN CONVECTIVE ACTIVITY. SO T NUMBER IN DOWNGRADED TO 2.5. THE SYSTEM CURRENTLY EVOLVES WITHIN A NEUTRAL TO UNFAVORABLE ENVIRONMENT. NORTHERLY VERTICAL WINDSHEAR STILL EXISTS BUT HAS WEAKENED A LITTLE BIT (ACCORDIND TO CIMSS DATA). LOW LEVEL INFLOW IS ESTABLISHED POLEWARD BUT NOT EQUATORWARD. THE SYSTEM TRACKS WESTWARDS, ALONG THE NORTHERN EDGE OF THE SUBTROPICAL RIDGE. BEYOND TAU 24, FIELDS AT 700 HPA BECOME WEAK, AND THE SYSTEM SHOULD SLOW DOWN. BEYOND THE FIRST STEP OF THE FORECAST, AVAILABLE DYNAMIC FORECAST STRONGLY DISAGREE. SOME OF THEM KEEP ON TRACKING WEST-SOUTHWESTWARDS (ARPEGE, UKMO, ALADIN), SOME CURVE SOUTHWARDS, EVEN SOUTHEASTWARDS (ECMWF, AND THE CONSENSUS MADE WITH THE AMERICAN MODELS). RSMC FORECAST IS A CONSENSUS, THAT HAS BEEN DISPLACED EASTWARDS AT THE END OF THE FORCAST TO BETTER FIT WITH THE ECMWF AND CONW (US MODELS CONSENSUS) SOLUTIONS. IT IS IMPORTANT TO NOTICE THAT THERE IS A STRONGER THAN USUAL UNCERTAINTY FOR BOTH TRACK AND INTENSITY FORCAST.