The African Monsoon Recent Evolution and Current Status Include Week-1 and Week-2 Outlooks

1. The African Monsoon Recent Evolution and Current StatusInclude Week-1 and Week-2 Outlooks Update prepared by Climate Prediction Center / NCEP 22 August 2016 For more information, visit: http://www.cpc.ncep.noaa.gov/products/Global_Monsoons/African_Monsoons/precip_monitoring.shtml

2. Outline • Highlights • Recent Evolution and Current Conditions • NCEP GEFS Forecasts • Summary

3. Highlights:Last 7 Days • Moderate to heavy rainfall resulted in moisture surpluses over many areas of the Sahel region of West Africa and partial areas of the Greater Horn of Africa. • Week-1 outlooks call for an increased chance for above-average rainfall over central Mali, Burkina Faso, western and southern Niger, northern Nigeria, and western Ethiopia. In contrast, there is an increased chance for below-average rainfall portions of Senegal, The Gambia, Guinea-Bissau, eastern Sudan, and South Sudan.

4. Rainfall Patterns: Last 7 Days During the past seven days, above-average rainfall was observed over portions of Senegal, Mali, Guinea-Conakry, Cote d’Ivoire, Burkina Faso, Togo, Benin, Nigeria, CAR, DRC, Sudan, South Sudan, Eritrea, and Ethiopia. In contrast, below-average rainfall was registered over localized areas of Guinea-Bissau, Sierra Leone, Burkina Faso, Nigeria, portions of Chad, Uganda, and Ethiopia.

5. Rainfall Patterns: Last 30 Days During the past 30 days, rainfall was above-average throughout portions of Mauritania, Senegal, Guinea-Conakry, Sierra Leone, Liberia, Mali, Cote d’Ivoire, Burkina Faso, Ghana, Togo, Benin, Niger, Nigeria, Cameroon, Chad, CAR, DRC, Sudan, South Sudan, Eritrea, Ethiopia, and parts of South Africa. In contrast, localized areas of Guinea-Conakry, Cote d’Ivoire, Nigeria, Niger, Nigeria, Chad, DRC, South Sudan, Uganda, Kenya, and Ethiopia received below-average rainfall.

6. Rainfall Patterns: Last 90 Days During the past 90 days, rainfall was above-average over portions of southern Mauritania, Senegal, Gambia, Guinea-Bissau, Guinea-Conakry, Sierra Leone, portions of Liberia, many parts of Cote d’Ivoire, Mali, Burkina Faso, portions of Niger and Ghana, Togo, Benin, portions of Nigeria, Cameroon, CAR, southern and central Chad, South Sudan, southern and eastern Sudan, northern Congo Brazzaville, parts of northern DRC, many parts of Ethiopia, Eritrea, portions of western Kenya, and portions of South Africa. In contrast, below-average rainfall was observed over local areas in Cote d’Ivoire, Ghana, portions of Nigeria, local areas in southern Cameroon, Equatorial Guinea, much of Gabon, southern Congo-Brazzaville, central and eastern DRC, much of Uganda and parts of Kenya, southern Ethiopia, southern Somalia, and portions of northern Tanzania.

7. Rainfall Patterns: Last 180 Days During the past 180 days, rainfall was above-average across portions of southern Mauritania, Senegal, Gambia, Guinea-Bissau, much of Mali, Guinea Conakry, Burkina Faso, Sierra Leone, parts of Cote d’Ivoire, portions of northern Ghana, western and central Niger, portions of Togo and Benin, portions of Nigeria, much of Cameroon, southern Chad, CAR, South Sudan, southern and eastern Sudan, many parts of Ethiopia, portions of Somalia, local areas in Gabon, Congo-Brazzaville, portions of DRC and Kenya, Tanzania, northern Mozambique, western Zambia, parts of Botswana, Zimbabwe, and portions of Madagascar, and South Africa. In contrast, below-average rainfall was observed over portions of Liberia and Cote d’Ivoire, southern Ghana, portions of Nigeria, local areas in southern Cameroon, eastern and southern Gabon, local areas in Congo Brazzaville, southern and eastern DRC, local areas in southern Ethiopia and southern Somalia, local areas in northern and eastern Kenya, Uganda, Angola, much of Namibia, portions of Zambia, central Malawi, southern Mozambique, and portions of South Africa and Madagascar.

8. Recent Rainfall Evolution Daily evolution of rainfall over the last 90 days at selected locations shows sustained moisture surpluses over parts of southern Mauritania (bottom left) and eastern Sudan (top right). In contrast, an erratic rainfall distribution resulted in rainfall deficits over southeastern South Sudan (bottom right).

9. Atmospheric Circulation:Last 7 Days The 700 hPa (left panel) wind anomalies featured an anomalous low-level cyclonic circulation over portions of the Sahel and strong low-level convergence from the Congo Air Boundary over parts of CAR, South Sudan, and southern Sudan.

10. NCEP GEFS Model ForecastsNon-Bias Corrected Probability of precipitation exceedance Week-1: Valid 23 – 29 August, 2016 Week-2: Valid 30 August – 5 September, 2016 For week-1 (left panel) and week-2 (right panel), there is an increased chance for weekly rainfall totals to exceed 50mm across portions of West and Central Africa, localized areas of western Sudan, parts of Eritrea and western Ethiopia.

11. Week-1 Precipitation Outlooks 23 – 29 August, 2016 • There is an increased chance for below-average rainfall across much of Senegal, The Gambia, and Guinea-Bissau: An area of anomalous lower-level divergence is expected to suppress rainfall in the region. Confidence: Moderate • There is an increased chance for above-average rainfall over southern Mali, Burkina Faso, northern Cote d’Ivoire, northern Ghana, northern Togo and Benin, southern Niger, and northern Nigeria: Anomalous lower-level convergence, combined with upper-level divergence is expected to enhance rainfall in the region. Confidence: Moderate • There is an increased chance for below-average rainfall over eastern Sudan and eastern South Sudan: An area of anomalous upper-level convergence is expected to suppress rainfall in the region. Confidence: Moderate • There is an increased chance for above-average rainfall over Eritrea and western Ethiopia: Stronger than normal southwesterly flow across DRC and South Sudan, with its associated lower-level convergence is expected to enhance rainfall in the region. Confidence: Moderate

12. Week-2 Precipitation Outlooks 30 August – 5 September, 2016 • There is an increased chance for above-average rainfall over portions of Senegal, The Gambia, southern Mali, Guinea-Bissau, Guinea-Conakry, Sierra Leone, portions of Cote d’Ivoire and Liberia: Anomalous lower-level convergence, coupled with anomalous upper-level divergence is expected to enhance rainfall in the region. Confidence: Moderate • There is an increased chance for below-average rainfall over eastern portions of Sudan and South Sudan: An area of anomalous upper-level convergence is expected to suppress rainfall in the region. Confidence: Moderate • There is an increased chance for above-average rainfall over western Ethiopia and Eritrea: A broad area of anomalous lower-level convergence, combined with upper-level divergence is expected to enhance rainfall in the region. Confidence: Moderate

13. Summary • During the past seven days, above-average rainfall was observed over portions of Senegal, Mali, Guinea-Conakry, Cote d’Ivoire, Burkina Faso, Togo, Benin, Nigeria, CAR, DRC, Sudan, South Sudan, Eritrea, and Ethiopia. In contrast, below-average rainfall was registered over localized areas of Guinea-Bissau, Sierra Leone, Burkina Faso, Nigeria, portions of Chad, Uganda, and Ethiopia. • During the past 30 days, rainfall was above-average throughout portions of Mauritania, Senegal, Guinea-Conakry, Sierra Leone, Liberia, Mali, Cote d’Ivoire, Burkina Faso, Ghana, Togo, Benin, Niger, Nigeria, Cameroon, Chad, CAR, DRC, Sudan, South Sudan, Eritrea, Ethiopia, and parts of South Africa. In contrast, localized areas of Guinea-Conakry, Cote d’Ivoire, Nigeria, Niger, Nigeria, Chad, DRC, South Sudan, Uganda, Kenya, and Ethiopia received below-average rainfall. • During the past 90 days, rainfall was above-average over portions of southern Mauritania, Senegal, Gambia, Guinea-Bissau, Guinea-Conakry, Sierra Leone, portions of Liberia, many parts of Cote d’Ivoire, Mali, Burkina Faso, portions of Niger and Ghana, Togo, Benin, portions of Nigeria, Cameroon, CAR, southern and central Chad, South Sudan, southern and eastern Sudan, northern Congo Brazzaville, parts of northern DRC, many parts of Ethiopia, Eritrea, portions of western Kenya, and portions of South Africa. In contrast, below-average rainfall was observed over local areas in Cote d’Ivoire, Ghana, portions of Nigeria, local areas in southern Cameroon, Equatorial Guinea, much of Gabon, southern Congo-Brazzaville, central and eastern DRC, much of Uganda and parts of Kenya, southern Ethiopia, southern Somalia, and portions of northern Tanzania. • Week-1 outlooks call for an increased chance for above-average rainfall over central Mali, Burkina Faso, western and southern Niger, northern Nigeria, and western Ethiopia. In contrast, there is an increased chance for below-average rainfall portions of Senegal, The Gambia, Guinea-Bissau, eastern Sudan, and South Sudan.