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 TECHNICAL BULLETIN (SOUTH-WEST INDIAN OCEAN) 0.A WARNING NUMBER : 28/12/20082009 1.A TROPICAL DEPRESSION 12 (EX-JADE) 2.A POSITION 2009/04/11 AT 0000 UTC : WITHIN 30 NM RADIUS OF POINT 27.3S / 55.4E (TWENTY SEVEN DECIMAL THREE DEGREES SOUTH AND FIFTY FIVE DECIMAL FOUR DEGREES EAST) MOVEMENT : SOUTH-EAST 22 KT 3.A DVORAK ANALYSIS : 2.5/2.5 /W 0.5/18 H 4.A CENTRAL PRESSURE : 997 HPA 5.A MAX AVERAGE WIND SPEED (10 MN) : 30 KT RADIUS OF MAXIMUM WINDS (RMW) : 90 KM 6.A EXTENSION OF WINDS BY QUADRANTS (KM): 30 KT NE: 180 SE: 470 SO: 180 NO: 090 7.A FIRST CLOSED ISOBARE (PRESSURE / AVERAGE DIAM): 1008 HPA / 900 KM 8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: MEDIUM 1.B FORECASTS: 12H: 2009/04/11 12 UTC: 30.9S/57.6E, MAX WIND=040KT , EXTRATROPICAL. 24H: 2009/04/12 00 UTC: 36.0S/58.2E, MAX WIND=050KT , EXTRATROPICAL. 36H: 2009/04/12 12 UTC: 40.0S/62.2E, MAX WIND=040KT , EXTRATROPICAL. 48H: 2009/04/13 00 UTC: 45.9S/67.2E, MAX WIND=030KT , DISSIPATING. 2.B OTHER INFORMATIONS: T=2.5, CI=2.5 IN RELATIONSHIP WITH THE OWN QUICK MOTION OF THE SYSTEM, RELATIVE WINDSHEAR HAS WEAKENED AND CONVECTIVE ACTIVITY IS CLOSER AGAIN TO THE LLCC ; LOW LEVEL CIRCULATION IS NOW ONLY PARTIALLY EXPOSED. JADE IS HOWEVER PENETRATING IN THE EXTRATROPICAL AREA AND ITS COOLER AND COOLER OCEAN TEMPERATURES AND WILL SOON BEGINNING ITS TRANSITION. ASCAT 1751Z SWATH SHOWS AS FORECASTED GALE FORCE 35/40KT UNFLAGED WINDS IN THE EASTERN SECTOR DUE TO THE GRADIENT EFFECT WITH THE SUBTROPICAL HIGH PRESSURES AND THE OWN MOTION OF THE SYSTEM. WINDS SHOULD TEMPORARELY STRENGHTEN ON AND AFTER THE EXTRATROPICAL TRANSITION BUT THE LOW IS EXPECTED TO DISSIPATE BEYOND TAU 48/60 MERGING IN A POLAR TROUGH.