THE CLIMATE OUTLOOK FORUM

From 18-19 December 1997 a Southern Africa Climate Outlook Forum convened to formulate consensus guidance for the January-March 1998 season in southern Africa. This Forum was a mid-season meeting to update the information provided by an earlier Forum that convened in Kadoma, Zimbabwe, on 8-12 September 1997. The Windhoek Forum reviewed the state of the global climate system and it's implications for southern Africa. One of the principal factors taken into account is the major El Niņo event on-going in the tropical Pacific Ocean. Recent El Niņo occurrences such as in 1982-83, 1991-92 and 1994-95 resulted in below-normal rainfall across much of the SADC region and disrupted climate patterns around the globe.

METHODOLOGY

The regional climate assessment began with consensus agreement that the current El Niņo will remain over the forecast period (January-March 1998). This and other factors affecting southern Africa's climate were assessed using coupled ocean-atmosphere models, physically-based statistical models and expert interpretation. The current status of seasonal to inter-annual forecasting allows prediction of spatial and temporal averages, and may not fully account for all factors that influence regional and national climate variability. This Outlook is relevant only to seasonal time scales and relatively large areas, and local variations may occur. Users are strongly advised to contact their National Meteorological Service for interpretation of this Outlook and for additional guidance.

The experts provided probability distributions to indicate the likelihood of below-, near- or above normal rainfall for each sub-region (see Map). Above-normal rainfall is defined as within the wettest third of recorded precipitation totals in each region over the period 1961 to 1990; below normal rainfall is defined as within the driest third of precipitation totals; near-normal is the third centered around the climatological median.

OUTLOOK

January through March covers much of the remainder of the rainy season for most of SADC. Exceptions are the northern and eastern part of Tanzania, and the far south-western part of South Africa.

Before the Tanzanian Long Rains, which usually start in March, above-normal rains are expected in northern and eastern Tanzania. The guidance on the map for this region is for January and February only and no guidance is provided for March. Near-normal rainfall is expected over the south-western half of Tanzania, northern and eastern Zambia, central and northern Malawi and northern Mozambique. Near-normal rainfall is expected also over north-western Zambia and the far north-western part of Namibia.

Over Mauritius and the south-western tip of South Africa, near-normal to above-normal rainfall conditions are expected.

The rest of continental southern Africa continues to have an increased risk of below-normal rainfall for January-March. Below-normal to near-normal rainfall is expected in northern Namibia and the southern half of Zambia. There is a strong indication of below-normal rainfall in central and southern Namibia, most of Botswana, Lesotho and much of South Africa.

There was some disagreement amongst models presented regarding how far east the strong indication of below-normal rainfall extends into north-eastern South Africa, Swaziland, southern Mozambique, southern Malawi and Zimbabwe. The strong risk of below-normal rainfall for eastern regions of southern Africa is a little less than indicated in the previous Forum Outlook, but is still considerable. Most models show no weakening of the risk of below-normal rainfall in January to March in these regions.

PARTICIPANTS

Participants at the Forum included representatives of Meteorological Services from eleven SADC countries (Botswana, Lesotho, Malawi, Mauritius, Mozambique, Namibia, South Africa, Swaziland, Tanzania, Zambia and Zimbabwe) and climate scientists and other experts from national, regional and international institutes (Drought Monitoring Centres - Harare and Nairobi;

University of Zululand; Clark University; SADC Food Security Technical and Administrative Unit; Southern Africa Transport and Communications Commission; the World Meteorological Organization; the Food and Agriculture Organization; the International Research Institute for Climate Prediction; the US National Oceanic and Atmospheric Administration Office of Global Programs and Climate Prediction Center; the US Agency for International Development; the UK Meteorological Office; IMGA/CNR-Bologna.)

Other Users at the Forum included representatives from the University of Botswana, Namibia Agricultural Union, Namibia Emergency Management Unit, Purdue University, World Vision, Namibia Department of Water Affairs, Namibia Agronomic Board, Zambia Food Reserve Agency,CICERO, Namibia Early Warning and Information System, Malawi Ministry of Agriculture and Irrigation, DFID/University of Greenwich, US Department of Agriculture, and the South Africa Department of Constitutional Development.

MAP CAPTION:

The numbers for each region indicate the probabilities of rainfall in each of the three categories, below, near and above-normal. The top number indicates the probability of rainfall occurring in the above-normal category, the middle number is for near-normal and the bottom for below normal. In the case of Mauritius, for example, there is a 40% probability of rainfall occurring in the above-normal category (i.e., within the range of the wettest third of recorded precipitation totals over the period 1961 to 1990); a 35% chance in the near-normal category; and a 25% chance in the below-normal category. Boundaries between sub-regions should be considered as transition zones.

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