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 : 22/12/20082009 1.A TROPICAL DEPRESSION 12 (EX-JADE) 2.A POSITION 2009/04/09 AT 1200 UTC : WITHIN 20 NM RADIUS OF POINT 22.6S / 50.2E (TWENTY TWO DECIMAL SIX DEGREES SOUTH AND FIFTY DECIMAL TWO DEGREES EAST) MOVEMENT : SOUTH-SOUTH-EAST 3 KT 3.A DVORAK ANALYSIS : 1.5/2.5 /W 1.0/24 H 4.A CENTRAL PRESSURE : 999 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: 060 SE: 250 SO: 150 NO: 040 7.A FIRST CLOSED ISOBARE (PRESSURE / AVERAGE DIAM): 1008 HPA / 400 KM 8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: SHALLOW 1.B FORECASTS: 12H: 2009/04/10 00 UTC: 24.1S/50.9E, MAX WIND=025KT, TROP. DISTURBANCE. 24H: 2009/04/10 12 UTC: 25.5S/52.7E, MAX WIND=030KT, BECOMING EXTRATROPICAL. 36H: 2009/04/11 00 UTC: 28.2S/55.0E, MAX WIND=030KT, EXTRATROPICAL. 48H: 2009/04/11 12 UTC: 32.7S/56.8E, MAX WIND=040KT, EXTRATROPICAL. 60H: 2009/04/12 00 UTC: 37.7S/58.3E, MAX WIND=045KT, EXTRATROPICAL. 72H: 2009/04/12 12 UTC: 40.2S/60.8E, MAX WIND=050KT, EXTRATROPICAL. 2.B OTHER INFORMATIONS: T=1.5+, CI=2.5- THE SYSTEM IS EXPECTED TO KEEPS ON TRACKING GLOBALLY SOUTHEASTWARDS SPEEDING UP TOWARDS A POLAR TROUGH WHICH WILL PROGRESSIVELY TAKING PLACE OF THE SUBTROPICAL HIGH PRESSURE BELT. ENVIRONMENTAL CONDITIONS ARE EXPECTED TO DEGRADE AS THE WEST-NORTHWESTERLY VERTICAL WINDSHEAR INCREASE AND AS SST DECREASE. WITHIN THE NEXT 24 HOURS, WINDS ARE EXPECTED TO WEAKEN NEAR TH CENTER BUT REMAIN STRONG (LOCALLY REACHING GALE FORCE WINDS) IN THE SOUTHERN SEMI-CIRCLE DUE TO THE GRADIENT EFFECT WITH THE SUBTROPICAL HIGH PRESSURES. THUNDERY AND HEAVY RAINY ACTIVITY EXTENDS UP TO 500NM IN THE EASTERN SEMI-CIRCLE PUSHED AWAY BY THE WINDSHEAR AND CONCERNS LA REUNION AND MAURITIUS (BUT SLIGHTEST FOR THE SECOND ONE) THIS INTABILITY OVER MASCARENES IS SUPPORTED BY THE CONVERGENCE BETWEEN NORTH-NORTHEASTERLY FLOW IN THE WAKE OF JADE AND EAST-NORTHEASTERLY TRADE WINDS FLOW AND BOOSTED BY UPPER LEVEL DIVERGENCE GENERATED BY THE ACCELERATING OF THE UPPER LEVEL JET (SEE 200 HPA WINDS AT 25KT OVER THE CENTER NEAR 23S GROWING UP TO MORE THAN 80KT NEAR 28S). THIS DISTURBED WAETHER SHOULD PERSIST UNTIL SATURDAY MORNING. IT SHOULD BEYOND TAU 36 MAKING ITS EXTRATROPICAL TRANSITION, WINDS COULD STRENGHTEN AGAIN AS THE LOW MERGE WITH THE POLAR TROUGH.