Seasonal forecasts for the forthcoming rainy season have been issued for southern Africa and the Greater Horn of Africa – regions which were impacted by the strong 2015-2016 El Niño.
The bulk of Southern African Development Community (SADC) is likely to receive normal to above-normal rainfall for most of the rainy season from October 2016 to March 2017. However, northern Democratic Republic of Congo, northern Angola, most of Tanzania, northern Mozambique, the Seychelles and eastern Madagascar are more likely to receive normal to below-normal rainfall.
There is an increased likelihood of below normal rainfall in the October to December rainy season over most of the equatorial parts of the Greater Horn of Africa, including central and eastern Ethiopia, Kenya, Tanzania, Somalia, Burundi, Rwanda and northern Uganda. Above normal rainfall is likely over the western parts of the equatorial sector, including much of South Sudan and western Ethiopia, and northwestern Sudan. There is also increased likelihood of warmer that average mean temperatures over much of the Greater Horn of Africa.
The respective outlooks were issued by the Southern Africa Regional Climate Outlook Forum and the Greater Horn of Africa Climate Outlook Forum. National meteorological services downscale the regional outlooks into national and local forecasts on sub-seasonal scales. WMO supports these efforts as part of its drive to improve user-friendly climate services to protect lives and livelihoods.
Thanks to scientific advances, seasonal climate outlooks have become an important planning tool for agriculture and food security, water and energy management, disaster risk reduction, and for the health sector. The climate outlook forums bring together weather and climate experts, development agencies and representatives of climate-sensitive sectors like water management.
The outlooks are based on expert opinion of climate scientists and a variety of forecast models of oceanic and atmospheric factors that influence the regional climate, including the El Niño-Southern Oscillation (ENSO).
Large parts of southern Africa were badly impacted by drought associated with the strong 2015-2016 El Niño, which has now ended. The warm phase (El Niño) is foreseen to shift through neutral to the cold phase, also referred to as La Niña, during the bulk of the rainfall season, according to the SADC outlook.
Some parts of the Greater Horn of Africa (such as Kenya and Uganda) received above average rainfall as a result of the El Niño episode, which – conversely – aggravated drought in parts of Ethiopia. The Greater Horn of Africa outlook took into account the likely negative phase of the Indian Ocean Dipole (IOD) mode and forecast weak to moderate La Niña conditions over the tropical Pacific Ocean during the forecast period. It said the influence of these ocean processes will be modulated by regional circulation systems, topography and large inland water bodies.
Above-normal rainfall is defined as lying within the wettest third of recorded 30 year average rainfall amounts; below-normal is defined as within the driest third of rainfall amounts and normal is the middle third, centred on the climatological median.