El Nino southern oscillation based rainfall forecasts in southern Africa. 1. seasonal forecasts can help communal farmers manage drought

Drought is the single most important natural disaster affecting some parts of southern Africa virtually every year. Because of the region's heavy dependence on rain-fed agriculture, drought is usually associated with widespread crop failure, livestock deaths, environmental degradation, famine and socio-economic stress. Reliable seasonal rainfall forecasts could lead to proactive drought mitigation strategies. In this study, the utility of probabilistic seasonal forecasts was examined in terms of forecast skill and timeliness for decision making. The Southern Oscillation Index (SOI) in spring was a useful indicator of summer rainfall (Nov-Mar) for c. 50% of stations in southern Africa and of drier than normal conditions for c. 20% of stations. The SOI average would have been useful to forecast severe droughts in parts of southern Africa between 1930 and 1992. The El Nino Southern Oscillation (ENSO) signal was greatest in central South Africa, Zimbabwe, Tanzania and Kenya. Forecast lead-times were 0-2 months, which was considered adequate for decision making by communal farmers - provided the forecasts were relevant and tailored for the local area. The climate analysis package Rainman International with international data is a useful forecasting tool on subcontinental and local scales. Training of agricultural extension officers in the use of climate analysis software like Rainman International is necessary to ensure effective dissemination to, and application of forecasts by, communal farmers