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 18 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 • Over the past week, moderate rains sustained moisture surpluses over the southern areas of Sudan and Chad. Southwestern Cote d'Ivoire received over 100 mm of rainfall over a two-day period this past week, bringing the last 30 day cumulative rainfall total to above 180% of normal rainfall. • Forecasts indicate that moisture surpluses will be sustained over southwestern Sudan and southern Chad over the next two weeks.

4. Rainfall Patterns: Last 7 Days During the past seven days, above-average rainfall was observed over much of Guinea-Conakry, Sierra Leone, parts of Liberia, western Cote d’Ivoire, southwestern Burkina Faso, parts of Togo and Benin, southern, south-central Niger, southern Chad, parts of northwestern DRC, parts of South Sudan Republic, western Kenya, western Eritrea, and central Ethiopia. In contrast, parts of Mali, eastern Cote d’Ivoire, parts of Ghana, eastern Burkina Faso, central and northern parts of Nigeria, Cameroon, Equatorial Guinea, Gabon, parts of Congo-Brazzaville, CAR, many portions of DRC, and Uganda had below-average rainfall.

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

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, 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, southern and eastern Angola, many parts of Ethiopia, Kenya, 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 Guinea-Conakry, southwestern Mali, parts of Sierra Leone and Liberia, local areas in Cote d’Ivoire and Ghana, parts of Nigeria, western Cameroon, much of Gabon, western and northern Angola, local areas in DRC, northeastern Ethiopia, parts of Botswana, Zimbabwe and Mozambique, and southeastern Madagascar.

7. Rainfall Patterns: Last 180 Days During the past 180 days, rainfall was above-average over portions of Guinea-Conakry, Sierra Leone, much of Cote d’Ivoire, Burkina Faso, parts of Ghana, Togo, Benin, parts of Nigeria, CAR, much of South Sudan, many parts of Ethiopia, southern Somalia, much of Kenya and Tanzania, Rwanda, Burundi, Uganda, Equatorial-Guinea, much of Congo-Brazzaville, DRC, many parts of Angola, Zambia, South Africa, northern Namibia, northern Botswana, many parts of Mozambique, Malawi, much of Zimbabwe, and northern and eastern Madagascar. In contrast, below-average rainfall was observed over the far western West Africa, coastal Sierra Leone and 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 reduce accumulated rainfall deficits over parts of Sierra Leone (bottom left). Many places in South Sudan 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 westerly flow was prevalent across in far Western Africa (left).

10. NCEP GEFS Model ForecastsNon-Bias Corrected Probability of precipitation exceedance Week-1: Valid 19 – 26 June, 2018 Week-2: Valid 27 June – 3 July, 2018 For week-1 (left panel), there is an increased chance for weekly rainfall totals to exceed 50mm across many parts of West Africa, and especially Nigeria. For week-2 (right panel), there is an increased chance for weekly rainfall totals to exceed 50mm across parts of most West African nations, as well as Chad, CAR, and western parts of Sudan.

11. Week-1 Precipitation Outlooks 19 – 25 June, 2018 • There is an increased chance for below-average rainfall over parts of Guinea, Guinea-Bissau, Senegal, and western Mali: An area of anomalous dry northerly flow is expected to supress 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 June, 2018 • There is an increased chance for above-average rainfall over Guinea, 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 much of Guinea-Conakry, Sierra Leone, parts of Liberia, western Cote d’Ivoire, southwestern Burkina Faso, parts of Togo and Benin, southern, south-central Niger, southern Chad, parts of northwestern DRC, parts of South Sudan Republic, western Kenya, western Eritrea, and central Ethiopia. In contrast, parts of Mali, eastern Cote d’Ivoire, parts of Ghana, eastern Burkina Faso, central and northern parts of Nigeria, Cameroon, Equatorial Guinea, Gabon, parts of Congo-Brazzaville, CAR, many portions of DRC, and Uganda had below-average rainfall. • During the past 30 days, parts of Guinea-Bissau, western Liberia, southwestern Mali, central and eastern Cote d’Ivoire, local areas in Ghana and Togo, southern and eastern Nigeria, western and central Cameroon, much of Gabon, local areas in Congo-Brazzaville and DRC, parts of Uganda, eastern and southern Ethiopia, parts of Somalia, and parts of northern Tanzania had below-average rainfall. In contrast, Guinea, Sierra Leone, local areas in Mali, western Cote d’Ivoire, parts of Ghana, Burkina Faso, northern Togo and Benin, western Niger, western and southern Nigeria, eastern Cameroon, southern Chad, parts of CAR, southern Sudan, South Sudan Republic, Congo-Brazzaville, northern Angola, DRC, parts of Uganda, Kenya, western Ethiopia, and parts of southern Somalia had above-average rainfall. • 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, 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, southern and eastern Angola, many parts of Ethiopia, Kenya, 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 Guinea-Conakry, southwestern Mali, parts of Sierra Leone and Liberia, local areas in Cote d’Ivoire and Ghana, parts of Nigeria, western Cameroon, much of Gabon, western and northern Angola, local areas in DRC, northeastern Ethiopia, parts of Botswana, Zimbabwe and Mozambique, and southeastern Madagascar. • Week-1 outlooks call for an increased chance for above-average rainfall over parts of Cote D'Ivoire, Burkina Faso, Ghana, Togo Benin, Nigeria, Cameroon, Chad, and western Sudan. In contrast, there is an increased chance for below-average rainfall over Guinea-Conakry, Guinea-Bissau, southern Senegal, and western Mali.