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 : 22/11/20062007 1.A SEVERE TROPICAL STORM 11 (HUMBA) 2.A POSITION 2007/02/26 AT 1200 UTC : 23.2S / 77.4E (TWENTY THREE DECIMAL TWO DEGREES SOUTH AND SEVENTY SEVEN DECIMAL FOUR DEGREES EAST) 3.A DVORAK ANALYSIS : 3.5/3.5 /S 4.A CENTRAL PRESSURE : 980 HPA 5.A MAX AVERAGE WIND SPEED (10 MN) : 50 KT 6.A EXTENSION OF WINDS BY QUADRANTS (KM): 30 KT NE: 300 SE: 450 SO: 350 NO: 250 50 KT NE: 050 SE: 080 SO: 080 NO: 050 7.A FIRST CLOSED ISOBARE (PRESSURE / AVERAGE DIAM): 1004 HPA / 1000 KM 8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP 1.B FORECASTS: 12H: 2007/02/27 00 UTC: 25.0S/77.6E, MAX WIND=050KT, SEVERE TROP. STORM. 24H: 2007/02/27 12 UTC: 26.8S/77.7E, MAX WIND=050KT, SEVERE TROP. STORM. 36H: 2007/02/28 00 UTC: 28.1S/77.1E, MAX WIND=050KT, BECOMING EXTRATROPICAL. 48H: 2007/02/28 12 UTC: 29.3S/77.3E, MAX WIND=050KT, EXTRATROPICAL. 60H: 2007/03/01 00 UTC: 30.6S/78.3E, MAX WIND=050KT, EXTRATROPICAL. 72H: 2007/03/01 12 UTC: 31.5S/81.0E, MAX WIND=050KT, EXTRATROPICAL. 2.B OTHER INFORMATIONS: T=CI=3.5+ "HUMBA" RESISTS RATHER WELL TO THE INCREASING NORTHWESTERLY VERTICAL WIND SHEAR, WITH DEEP CONVECTION WHICH HAS REBUILT NEAR THE CENTER DURING THE LAST 8 HOURS, RESULTING A STATIONNARY INTENSITY OF SEVERE TROPICAL STORM. DUE TO THIS NORTHWESTERLY VERTICAL WINDSHEAR, THE LOW LEVEL CENTER IS LOCATED ON THE NORTHWESTERN EDGE OF DEEP CONVECTION. LOW LEVEL CIRCULATION IS STILL WELL ESTABLISHED, WITH STRONG WINDS MAINLY IN THE SOUTHERN GRADIENT DUE TO GRADIENT EFFECT WITH SUBTROPICAL HIGH PRESSURES. "HUMBA" IS EXPECTED TO KEEP ON TRACKING MAINLY SOUTHWARDS BECOMING EXTRATROPICAL OVER SEAS SOUTH OF 25 SOUTH WHERE SST ARE UNDER 26 DEGRES CELSIUS. UNDER THE OPPOSITE STEERING FLOWS OF A MIDLEVEL RIDGE LOCATED EAST OF THE SYSTEM (SOUTHWARDS STEERING FLOW FOR A WELL STRUCTURED SYSTEM), AND LOW LEVEL SUBTROPICAL HIGH PRESSURES WICH TRANSIT TO THE SOUTH DURING THE NEXT 36 HOURS (WICH SHOULD MAKE THE LOW LEVEL VORTEX TRACK SOUTHWESTWARDS IN CASE OF SHEARING), THE LLCC SHOULD TRACK SOUTH, THEN TEMPORARILLY SOUTHWESTWARDS AT MEDIUM RANGE, BEFORE EVACUATE SOUTHEASTWARDS IN THE WESTERLIES.