Period: 10 - 20 March 2001
Synoptic review
The middle (500 hPa) level cyclonic circulations centred over the northern Botswana and Zambia were the dominant features during the second dekad of the month of March. At the same time, the southern limit of the Inter-Tropical-Convergence Zone (ITCZ) was oscillating over Zambia and Angola. This resulted in convective activity over the northern area of the sub-region for most of the period under review. Meanwhile the effect of the Inter-Tropical-Convergence Zone (ITCZ) over the southwest Indian Ocean remained active along the ten degrees latitude with westward and south-westward migrating tropical disturbances from time to time.
Figure 1 illustrates the typical middle (500hPa) level average circulation pattern over the sub-region during most of the period under review.
Rainfall summary
During the second dekad of March generally wet conditions prevailed across the eastern and central areas of the sub-region while dry conditions prevailed over the south-western and the north-eastern parts of the sub-region. The rainfall distribution and percentage of normal across the sub-region during the third dekad of the month are illustrated in Figures 2(a) and 2(b) .
Countries of the sub-region including, most of Tanzania, extreme north-eastern and southern part of Mozambique, Botswana, Seychelles, most of Zimbabwe, south of Angola, most of South Africa, Swaziland, Lesotho, south-western and eastern Zambia and Mauritius received 60 mm or less rainfall during the period under review. North and eastern Zimbabwe, most of Mozambique, Lesotho, north and central Zambia, south-western and southern tip of Tanzania, eastern interior of South-Africa, northern Angola and Malawi received more than 60 mm rainfall during this period. The highest rainfall (>150mm) was recorded in central Mozambique extending northwards and over the northeast of South Africa, Figure 2(a) .
Meanwhile, Figure 2(b) shows that normal to above normal rainfall was recorded over the eastern, south-western and central part of the SADC region. Below normal conditions prevailed over northern and southern tip of South Africa, central Botswana, most of Tanzania, north-eastern and southern Mozambique, Mauritius and Seychelles with less than 65 % of their average for the period under review.
Outlook for the period 1 to 15 April 2001
Most forecast models are anticipating a middle level (500hPa) high-pressure system over the south-western sector coupled with periodic westerly troughs over the south eastern tip of South Africa. The ITCZ is expected to remain active over the northern most part of the sub-region. An intense Tropical depression over the Indian Ocean is expected to traverse the eastern sector of Mauritius during the beginning of the outlook period. This is consistent with the current trends in the circulation pattern.
As a result of the anticipated synoptic patterns, dry conditions are expected over the sub-region covering most of Namibia, most of Botswana and most of Zimbabwe, most of South Africa, Lesotho, southern and central Mozambique. Occasional outbreaks of rainfall are likely to occur over the northern tip of Namibia, northern Botswana and northern Zimbabwe, southern Zambia, northern Mozambique, Swaziland, Mauritius and Seychelles towards the beginning of the outlook period. Meanwhile, wet conditions are anticipated over the northern parts of the sub-region covering DRC, Angola, most of Tanzania, Malawi, northern Zambia, and northern Mozambique during the outlook period.
Issued by:
Drought Monitoring Centre
P.O Box BE150
Belvedere, Harare, Zimbabwe
Tel/Fax: +263 4 778172
Email: dmcgen@dmc.co.zw
Web: www.dmc.co.zw