1. The African Monsoon Recent Evolution and Current Status Include Week-1 and Week-2 Outlooks Update prepared by Climate Prediction Center / NCEP 18 May 2015 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 Guinea-Conakry, Sierra Leone, Gabon, and portions of DRC and western Ethiopia, whereas suppressed rainfall prevailed over Uganda and parts of southern Ethiopia. Week-1 outlooks call for an increased chance for above-average rainfall over southern and eastern Guinea-Conakry, Sierra Leone, Liberia, western Cote d'Ivoire, southern Cameroon, Equatorial Guinea, Gabon, Congo-Brazzaville, and portions of western DRC. In contrast, there is an increased chance for below-average rainfall over eastern Conte d'Ivoire, southern Ghana, Togo, southern Benin and southern Nigeria.

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

5. Rainfall Patterns: Last 30 Days During the past 30 days, rainfall was above-average over portions of Guinea and Cote d’Ivoire, southeastern Cameroon, Equatorial Guinea, much of Gabon, western CAR, central and southern DRC, eastern Angola, parts of Botswana, Zimbabwe, Zambia, portions of Ethiopia, local areas in Somalia, Uganda, Kenya, and Tanzania. In contrast, local areas in in southern Mali, Burkina Faso, southern Cote d’Ivoire, Ghana, Togo, Benin, much of Nigeria and Cameroon, eastern CAR, Congo-Brazzaville, western Angola, northern DRC, parts of southern Ethiopia, northeastern Kenya, and northern Madagascar had below-average rainfall.

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

7. Rainfall Patterns: Last 180 Days During the past 180 days, rainfall was above-average over parts of Liberia, Cote d’Ivoire, southern Ghana, southern Nigeria, many parts of CAR, western Gabon, northern Congo- Brazzaville, portions DRC, southern Malawi, much of Mozambique, Botswana, Zimbabwe, and Madagascar. In contrast, portions of southeastern Mali, Burkina Faso, northern Ghana, northern Nigeria, portions of Cameroon, southern Gabon, southern Congo-Brazzaville, Angola, portions of DRC, Namibia, local areas in Zambia, and portions of South Africa had below-average rainfall.

8. Recent Rainfall Evolution Daily evolution of rainfall over the last 90 days at selected places reflects that seasonal total rainfall remained below-average over portions of Nigeria (bottom left) and eastern Ethiopia (top right). In contrast, portions of southern Somalia had above average rainfall (bottom right).

9. Atmospheric Circulation: Last 7 Days The 850hpa wind anomalies featured stronger than normal sub-tropical anti-cyclone over Northwest Africa and the neighboring areas.

10. NCEP GEFS Model Forecasts Non-Bias Corrected Probability of precipitation exceedance Week-1: Valid 19 May – 25 May 2015 Week-2: Valid 26 May – 01 June 2015 For week-1 (left panel) and week-2 (right-panel), there is an increased chance for rainfall to exceed 50 mm over Sierra Leone, Liberia, portions of Cameroon, Gabon, southern Congo-Brazzaville, and western Ethiopia.

11. Week-1 Precipitation Outlooks 19 May – 25 May 2015 1.There is an increased chance for above-average rainfall over southern and eastern Guinea-Conakry, Sierra Leone, Liberia and western Cote d'Ivoire: Anomalous lower-level southwesterly flow from the Atlantic Ocean, with its associated lower-level convergence is expected to enhance rainfall in the region. Confidence: Moderate 2.There is an increased chance for below-average rainfall over eastern Conte d'Ivoire, southern Ghana, Togo, southern Benin and southern Nigeria: Anomalous lower- level wind divergence is expected to suppress rainfall in the region. Confidence: Moderate 3.There is an increased chance for above-average rainfall over southern Cameroon, Equatorial Guinea, Gabon, Congo-Brazzaville, and portions of western DRC: Anomalous lower level-convergence combined with a broad area of upper -level divergence is expected to enhance rainfall in the region. Confidence: Moderate

12. Week-2 Precipitation Outlooks 26 May – 01 June 2015 1.There is an increased chance for below-average rainfall over southern and eastern Cote d'Ivoire, southern Ghana, Togo, southern Benin and southeastern Nigeria: Anomalous lower-level northerly flow with its associated lower-level divergence is expected to suppress rainfall in the region. Confidence: Moderate 2.There is an increased chance for above-average rainfall over portions of southeastern Nigeria, Cameroon, western CAR, Equatorial-Guinea, Gabon, and Congo- Brazzaville: Anomalous lower-level southwesterly flow from the Atlantic Ocean, combined with lower-level convergence and a broad area of 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 Guinea-Conakry, Sierra Leone, local areas in Benin and western Nigeria, much of Gabon, southern Congo-Brazzaville, southwestern DRC, local areas in southern Chad, portions of CAR and South Sudan, and western Ethiopia. In contrast, parts of Liberia and Cote d’Ivoire, Ghana, many parts of Nigeria, northern Congo- Brazzaville, northern and eastern DRC, southern South Sudan Republic, much of Uganda, portions of southern Ethiopia and southern Somalia had below-average rainfall. During the past 30 days, rainfall was above-average over portions of Guinea and Cote d’Ivoire, southeastern Cameroon, Equatorial Guinea, much of Gabon, western CAR, central and southern DRC, eastern Angola, parts of Botswana, Zimbabwe, Zambia, portions of Ethiopia, local areas in Somalia, Uganda, Kenya, and Tanzania. In contrast, local areas in in southern Mali, Burkina Faso, southern Cote d’Ivoire, Ghana, Togo, Benin, much of Nigeria and Cameroon, eastern CAR, Congo-Brazzaville, western Angola, northern DRC, parts of southern Ethiopia, northeastern Kenya, and northern Madagascar had below-average rainfall. During the past 90 days, rainfall was above-average over Guinea-Conakry, Sierra Leone, Cote d’Ivoire, southwestern Ghana, Benin, southern Nigeria, portions of Cameroon, Equatorial Guinea, much of Gabon, Congo-Brazzaville, central and southern CAR, South Sudan Republic, many parts of DRC, parts of Uganda and Ethiopia, Kenya, southern Somalia, many parts of Tanzania, Zambia, Botswana, Zimbabwe, central and northern Mozambique and many parts of Madagascar. In contrast, Sierra Leone, Liberia, portions of southern Mali, Burkina Faso, northern Nigeria, northern Cameroon, southern Gabon, Angola, Namibia, many parts of South Africa, southern Mozambique, Malawi, portions of Tanzania, many parts of Ethiopia and northern Madagascar had below-average rainfall. Week-1 outlooks call for an increased chance for above-average rainfall over southern and eastern Guinea-Conakry, Sierra Leone, Liberia, western Cote d'Ivoire, southern Cameroon, Equatorial Guinea, Gabon, Congo-Brazzaville, and portions of western DRC. In contrast, there is an increased chance for below-average rainfall over eastern Conte d'Ivoire, southern Ghana, Togo, southern Benin and southern Nigeria.