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 29 May 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 • Moderate to heavy rainfall sustained moisture surpluses across eastern Sudan and South Sudan, western Ethiopia, western Kenya, Uganda and parts of DRC. • Week-1 outlooks call for an increased chance for below-average rainfall over parts of Cote d'Ivoire, Ghana, Togo, Benin, western Nigeria, and parts of central DRC. In contrast, there is an increased chance for above-average rainfall over parts of northeastern DRC, CAR, South Sudan Republic, Uganda, western Kenya, southeastern Sudan, and Ethiopia.

4. Rainfall Patterns: Last 7 Days During the past seven days, rainfall was below-average over parts of Guinea-Conakry, Nigeria, portions of Cameroon and Gabon, parts of CAR, and southern Congo-Brazzaville. In contrast, Liberia, Cote d’Ivoire, southern Ghana, western Niger, parts of Chad, eastern CAR, local areas in Congo-Brazzaville, DRC, parts of Sudan, South Sudan Republic, parts of Ethiopia, Uganda, parts of Kenya, and local areas in southern Somalia had above-average rainfall.

5. Rainfall Patterns: Last 30 Days During the past 30 days, much of Guinea-Conakry, Sierra Leone, parts of Liberia, southeastern Mali, local areas in Cote d’Ivoire, parts of Burkina Faso, northern Ghana, parts of Togo and Benin, portions of Nigeria, western Cameroon, many parts of Gabon, local areas in South Sudan, and portions of Ethiopia, and local areas in Kenya and Somalia had below-average rainfall. In contrast, many parts of Cote d’Ivoire, southern Ghana, portions of Nigeria, eastern Cameroon, much of CAR, northern Angola, DRC, Rwanda, Burundi, parts of Uganda and South Sudan, parts of Kenya, parts of Ethiopia, parts of southern Somalia, and local areas in Tanzania had above-average rainfall.

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

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

8. Recent Rainfall Evolution Daily evolution of rainfall over the last 90 days at selected locations shows that seasonal total rainfall remained below-normal over parts of Guinea (bottom left) and Gabon (bottom right). In contrast, moderate to heavy rainfall sustained moisture surpluses over parts of western Ethiopia (top right).

9. Atmospheric Circulation:Last 7 Days An area of anomalous lower-level southwesterly flow was observed in the area between Gabon and Sudan.

10. NCEP GEFS Model ForecastsNon-Bias Corrected Probability of precipitation exceedance Week-1: Valid 30 May – 5 June, 2018 Week-2: Valid 6 – 12 June, 2018 For week-1 (left panel) and week-2 (right panel), there is an increased chance for weekly rainfall totals to exceed 50mm parts of Nigeria and Cameroon, northeastern DRC, and western Kenya and Ethiopia.

11. Week-1 Precipitation Outlooks 30 May – 5 June, 2018 • There is an increased chance for below-average rainfall over parts of Cote d'Ivoire, Ghana, Togo, Benin and Nigeria: An area of anomalous lower level divergence is expected to suppress rainfall in the region. Confidence: Moderate • There is an increased chance for below-average rainfall over parts of central DRC: An area of anomalous lower-level divergence and upper-level convergence is expected to suppress rainfall in the region.. Confidence: Moderate • There is an increased chance for above -average rainfall over parts of northeastern DRC, CAR, South Sudan, Uganda, Kenya, Sudan, and Ethiopia:An area of anomalous lower-level convergence, upper-level divergence, and the associated phase of the MJO is expected to enhance rainfall in the region. Confidence: Moderate

12. Week-2 Precipitation Outlooks 6 – 12 June, 2018 • There is an increased chance for above-average rainfall over parts of Cote d'Ivoire, Ghana, Togo, Benin, Burkina Faso, Niger, Nigeria, Cameroon, Chad and CAR: A broad area of anomalous lower-level convergence and upper-level divergence is expected to enhance rainfall in the region. Confidence: Moderate • There is an increased chance for below-average rainfall over parts of Congo and DRC: An area of anomalous lower-level divergence and upper-level convergence is expected to suppress rainfall in the region. Confidence: Moderate • There is an increased chance for above-average rainfall over parts of eastern DRC, Uganda, South Sudan, Sudan, Kenya and Ethiopia: An area of anomalous lower-level convergence and pockets of upper-level divergence is expected to enhance rainfall in the region. Confidence: Moderate

13. Summary • During the past seven days, rainfall was below-average over parts of Guinea-Conakry, Nigeria, portions of Cameroon and Gabon, parts of CAR, and southern Congo-Brazzaville. In contrast, Liberia, Cote d’Ivoire, southern Ghana, western Niger, parts of Chad, eastern CAR, local areas in Congo-Brazzaville, DRC, parts of Sudan, South Sudan Republic, parts of Ethiopia, Uganda, parts of Kenya, and local areas in southern Somalia had above-average rainfall • During the past 30 days, much of Guinea-Conakry, Sierra Leone, parts of Liberia, southeastern Mali, local areas in Cote d’Ivoire, parts of Burkina Faso, northern Ghana, parts of Togo and Benin, portions of Nigeria, western Cameroon, many parts of Gabon, local areas in South Sudan, and portions of Ethiopia, and local areas in Kenya and Somalia had below-average rainfall. In contrast, many parts of Cote d’Ivoire, southern Ghana, portions of Nigeria, eastern Cameroon, much of CAR, northern Angola, DRC, Rwanda, Burundi, parts of Uganda and South Sudan, parts of Kenya, parts of Ethiopia, parts of southern Somalia, and local areas in Tanzania had above-average rainfall. • During the past 90 days, above-average rainfall was observed over eastern Guinea-Conakry, much of Cote d’Ivoire, parts of Ghana, southwestern Burkina Faso, Togo, Benin, portions of Nigeria, much of Cameroon, CAR, South Sudan, much of Congo-Brazzaville, many parts of DRC, portions of Angola, western and southern Ethiopia, Kenya, Uganda, Somalia, Tanzania, Zambia, much of Zimbabwe, Botswana, many parts of Mozambique and South Africa, and northwestern Madagascar. In contrast, rainfall was below-average over much of Guinea, southern Mali, southern Sierra Leone and southern Liberia, parts of Nigeria, much of Gabon, local areas in Congo-Brazzaville, western and northern Angola, local areas in DRC and Ethiopia, western and southern Namibia, parts of South Africa, and southeastern Madagascar. • Week-1 outlooks call for an increased chance for below-average rainfall over parts of Cote d'Ivoire, Ghana, Togo, Benin, western Nigeria, and parts of central DRC. In contrast, there is an increased chance for above-average rainfall over parts of northeastern DRC, CAR, South Sudan Republic, Uganda, western Kenya, southeastern Sudan, and Ethiopia.