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 19 June 2018 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 • Above-average rainfall was observed over parts of Guinea-Conakry, Sierra Leone, western Burkina Faso, portions of Cote d’Ivoire, southern Nigeria, southern Chad, southern Sudan, and parts of Ethiopia. • Week-1 outlooks call for an increased chance for above-average rainfall over parts of Guinea-Conakry, Guinea-Bissau, Senegal, and western Mali. In contrast, there is an increased chance for below-average rainfall over parts of Ghana, Burkina Faso, Togo, Benin, Nigeria, southern Niger, Cameroon, Chad, Central Africa Republic, and western Sudan.

4. Rainfall Patterns: Last 7 Days During the past seven days, above-average rainfall was observed over parts of Guinea-Conakry, Sierra Leone, western Burkina Faso, portions of Cote d’Ivoire, southern Nigeria, southern Chad, southern Sudan, and parts of Ethiopia. In contrast, parts of Burkina Faso and Ghana, parts of central and northern Nigeria, parts of Cameroon, CAR, northern DRC, portions of South Sudan and local areas in Ethiopia had below-average rainfall.

5. Rainfall Patterns: Last 30 Days During the past 30 days, much of Guinea-Conakry, Sierra Leone, Liberia, western Cote d’Ivoire, parts of Ghana and Burkina Faso, western Niger, northern Benin, western and southern Nigeria, southern Chad, parts of Congo-Brazzaville, CAR, northern Angola, portions of DRC, southern Sudan, South Sudan Republic, parts of Uganda, western Kenya, protons of Ethiopia, and local areas in Somalia had above-average rainfall. In contrast, below-average rainfall was observed local areas in Mali, eastern Cote d’Ivoire, local areas in Ghana, Togo and Benin, portions of Nigeria, Equatorial Guinea, Gabon, local areas in CAR and Congo-Brazzaville, portions of DRC, and local areas in Uganda and Ethiopia.

6. Rainfall Patterns: Last 90 Days During the past 90 days, above-average rainfall was observed over parts of Guinea-Conakry, western Sierra Leone and eastern Liberia, parts of Cote d’Ivoire and Ghana, parts of Burkina Faso, northern Togo and Benin, portions of Nigeria, eastern Cameroon, CAR, South Sudan Republic, parts of Southern Sudan, much of Congo-Brazzaville, many parts of DRC, many parts of Angola, many parts of Ethiopia, Kenya, parts of Uganda, Somalia, Tanzania, northern Namibia, northern Zambia, parts of Zimbabwe and Botswana, Mozambique, South Africa, and many parts of Madagascar. In contrast, rainfall was below-average over local areas in Senegal, southwestern Mali, portions of Liberia, eastern Cote d’Ivoire, parts of Ghana, Togo and Benin, portions of Nigeria, western Cameroon, much of Gabon, northwestern and northern Angola, local areas in DRC, northeastern Ethiopia, and southeastern Madagascar.

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

8. Recent Rainfall Evolution Daily evolution of rainfall over the last 90 days at selected locations shows that light to moderate rainfall helped to offset accumulated rainfall deficits over parts of Guinea-Conakry (bottom left). Many places in western Ethiopia continued to receive above-average rainfall (top right). In contrast, seasonal total rainfall remained below-normal over parts of Gabon (bottom right).

9. Atmospheric Circulation:Last 7 Days Anomalous lower-level onshore-flow with its associated convergence was observed across portions of West Africa (left).

10. NCEP GEFS Model ForecastsNon-Bias Corrected Probability of precipitation exceedance Week-1: Valid 20 – 26 June, 2018 Week-2: Valid 27 June – 3 July, 2018 For week-1 (left panel), and week-2 (right panel), there is an increased chance for weekly rainfall totals to exceed 50mm across the Gulf of Guinea and the neighboring areas of the Sahel countries, parts of the Lake Victoria region, and western Ethiopia.

11. Week-1 Precipitation Outlooks 19 – 26 June, 2018 • There is an increased chance for below-average rainfall over parts of Guinea-Conakry, Guinea-Bissau, Senegal, and western Mali: An area of anomalous dry northerly flow is expected to suppress rainfall in the region. Confidence: Moderate • There is an increased chance for above-average rainfall over parts of Cote D'Ivoire, Burkina Faso, Ghana, Togo Benin, Nigeria, Cameroon, Chad, and western Sudan: An area of anomalous lower-level convergence and upper-level divergence is expected to enhance rainfall in the region. Confidence: Moderate

12. Week-2 Precipitation Outlooks 27 June – 3 July, 2018 • There is an increased chance for above-average rainfall over Guinea-Conakry, Sierra Leone, Liberia and southwestern Mali: An area of 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 above-average rainfall over parts of Ghana, Burkina Faso, Togo, Benin, Nigeria, southern Niger, Cameroon, Chad, Central Africa Republic, and western Sudan: An area of anomalous lower-level convergence and 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 parts of Guinea, Sierra Leone, western Burkina Faso, portions of Cote d’Ivoire, southern Nigeria, southern Chad, southern Sudan, and parts of Ethiopia. In contrast, parts of Burkina Faso and Ghana, parts of central and northern Nigeria, parts of Cameroon, CAR, northern DRC, portions of South Sudan and local areas in Ethiopia had below-average rainfall. • During the past 30 days, much of Guinea-Conakry, Sierra Leone, Liberia, western Cote d’Ivoire, parts of Ghana and Burkina Faso, western Niger, northern Benin, western and southern Nigeria, southern Chad, parts of Congo-Brazzaville, CAR, northern Angola, portions of DRC, southern Sudan, South Sudan Republic, parts of Uganda, western Kenya, protons of Ethiopia, and local areas in Somalia had above-average rainfall. In contrast, below-average rainfall was observed local areas in Mali, eastern Cote d’Ivoire, local areas in Ghana, Togo and Benin, portions of Nigeria, Equatorial Guinea, Gabon, local areas in CAR and Congo-Brazzaville, portions of DRC, and local areas in Uganda and Ethiopia. • During the past 90 days, above-average rainfall was observed over parts of Guinea-Conakry, western Sierra Leone and eastern Liberia, parts of Cote d’Ivoire and Ghana, parts of Burkina Faso, northern Togo and Benin, portions of Nigeria, eastern Cameroon, CAR, South Sudan Republic, parts of Southern Sudan, much of Congo-Brazzaville, many parts of DRC, many parts of Angola, many parts of Ethiopia, Kenya, parts of Uganda, Somalia, Tanzania, northern Namibia, northern Zambia, parts of Zimbabwe and Botswana, Mozambique, South Africa, and many parts of Madagascar. In contrast, rainfall was below-average over local areas in Senegal, southwestern Mali, portions of Liberia, eastern Cote d’Ivoire, parts of Ghana, Togo and Benin, portions of Nigeria, western Cameroon, much of Gabon, northwestern and northern Angola, local areas in DRC, northeastern Ethiopia, and southeastern Madagascar. • Week-1 outlooks call for an increased chance for above-average rainfall over parts of Guinea-Conakry, Guinea-Bissau, Senegal, and western Mali. In contrast, there is an increased chance for below-average rainfall over parts of Ghana, Burkina Faso, Togo, Benin, Nigeria, southern Niger, Cameroon, Chad, Central Africa Republic, and western Sudan.