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 25 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 • Below-average rainfall was observed across the far western West Africa. • Weekly rainfall surpluses exceeded 100mm over parts of Cote d’Ivoire, southern Nigeria, and western Central African Republic. • Week-1 outlooks call for an increased chance for above-average rainfall over much of Guinea-Conakry, Sierra Leone, western Liberia, parts of southern Mali, western Burkina Faso, northwestern Cote d’Ivoire, northeastern Benin, much of Nigeria, western and northern Cameroon, southern Chad, western Sudan, and northern Central African Republic.

4. Rainfall Patterns: Last 7 Days During the past seven days, below-average rainfall was observed over parts of Senegal, Gambia, Guinea-Bissau, Guinea-Conakry, Sierra Leone, western Liberia, southwestern Mali, and local areas in DRC, parts of South Sudan and Ethiopia. In contrast, central Mali, eastern Liberia, many parts of Cote d’Ivoire, local areas in Ghana, Benin and Togo, parts of Niger and Nigeria, Cameroon, central and southern Chad, portions of CAR and DRC, western and eastern Sudan, parts of South Sudan Republic and Ethiopia, and local areas in Uganda had above-average rainfall.

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

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

7. Rainfall Patterns: Last 180 Days During the past 180 days, rainfall was above-average over southern and eastern Guinea-Conakry, parts of Mali, parts of Sierra Leone and Liberia, much of Cote d’Ivoire, Burkina Faso, parts of Ghana, Togo and Benin, parts of Nigeria, central and 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, portions 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, southern Liberia, parts of Ghana, southern Togo, parts of Nigeria, Gabon, portions of DRC and Angola, northeastern Ethiopia, many parts of Namibia, central and 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 early season moisture deficits are evident over the far western West Africa (bottom left). Light to moderate rainfall sustained moisture surpluses over parts of South Sudan (bottom right) and Ethiopia (top right).

9. Atmospheric Circulation:Last 7 Days Anomalous lower-level anticyclonic circulation and its associated dry easterly flow may have contributed to suppressing rainfall over the far western West Africa.

10. NCEP GEFS Model ForecastsNon-Bias Corrected Probability of precipitation exceedance Week-1: Valid 26 June – 2 July, 2018 Week-2: Valid 3 – 9 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 portions of the Gulf of Guinea and the neighboring areas of the Sahel countries, and western Ethiopia.

11. Week-1 Precipitation Outlooks 26 June – 2 July, 2018 • There is an increased chance for above-average rainfall over much of Guinea-Conakry, Sierra Leone, northern Liberia, parts of southwestern Mali, northern Cote d’Ivoire, and western Burkina Faso: An 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 above-average rainfall over parts of Benin, Nigeria, Cameroon, Chad, western Sudan, and northern Central African Republic: 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 3 - 9 July, 2018 • There is an increased chance for above-average rainfall over much of Guinea-Conakry, Sierra Leone, southern Mali, northern Cote D'Ivoire, parts of Ghana, Burkina Faso, Togo, Benin, Nigeria, southern Niger, Cameroon, Chad, Central African 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, below-average rainfall was observed over parts of Senegal, Gambia, Guinea-Bissau, Guinea-Conakry, Sierra Leone, western Liberia, southwestern Mali, and local areas in DRC, parts of South Sudan and Ethiopia. In contrast, central Mali, eastern Liberia, many parts of Cote d’Ivoire, local areas in Ghana, Benin and Togo, parts of Niger and Nigeria, Cameroon, central and southern Chad, portions of CAR and DRC, western and eastern Sudan, parts of South Sudan Republic and Ethiopia, and local areas in Uganda had above-average rainfall. • During the past 30 days, below-average rainfall was observed over much of Senegal, Gambia, Guinea-Bissau, southwestern Mali, central Liberia, eastern Cote d’Ivoire, parts of Ghana and Benin, portions of Nigeria and Cameroon, Equatorial Guinea, Gabon, local areas in CAR, parts of Congo-Brazzaville and DRC, and local areas in Uganda and South Sudan Republic. In contrast, much of Guinea-Conakry, Sierra Leone, portions of Liberia and Mali, many parts of Cote d’Ivoire, parts of Ghana and Burkina Faso, western Niger, parts of Togo and Benin, portions of Nigeria, central and southern Chad, local areas in Cameroon, northern Congo-Brazzaville, parts of CAR, local areas in DRC, southern Sudan, South Sudan Republic, parts of Uganda, western Kenya, and portions of Ethiopia had above-average rainfall. • During the past 90 days, above-average rainfall was observed over local areas in Guinea-Conakry, western Sierra Leone and eastern Liberia, parts of Cote d’Ivoire and Ghana, central Mali, parts of Burkina Faso, Togo and Benin, southern Niger, portions of Nigeria, eastern Cameroon, central and southern Chad, CAR, South Sudan Republic, Southern Sudan, much of Congo-Brazzaville, many parts of DRC and Angola, much of Ethiopia, Kenya, parts of Uganda, Somalia, Tanzania, Namibia, northern Zambia, parts of Zimbabwe, southern Botswana, Mozambique, South Africa, and western Madagascar. In contrast, rainfall was below-average over much of Senegal, Gambia, Guinea-Bissau, portions of Guinea-Conakry, 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 much of Guinea-Conakry, Sierra Leone, western Liberia, parts of southern Mali, western Burkina Faso, northwestern Cote d’Ivoire, northeastern Benin, much of Nigeria, western and northern Cameroon, southern Chad, western Sudan, and northern CAR.