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 27 July 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 • Portions of the Sahel countries received above-average rainfall, whereas suppressed rainfall continued to prevail over northern and eastern Ethiopia. • Week-1 outlooks call for an increased chance for above-average rainfall over southern Senegal, Guinea, Guinea-Bissau, Sierra Leone, southern and central Mali, Burkina Faso, portions of northern Cote d'Ivoire and Ghana, southwestern Niger, western Ethiopia and eastern South Sudan Republic. In contrast, there is an increased chance for below-average rainfall over southern Cameroon, Gabon, Equatorial Africa, Congo, western DRC, and eastern Ethiopia.

4. Rainfall Patterns: Last 7 Days During the past seven days, above-average rainfall was observed over much of Guinea, Sierra Leone, Liberia, portions of Mali and Niger, Nigeria, Cameroon, western CAR, southeastern South Sudan and portions of western Ethiopia. In contrast, parts of Senegal, Cote d’Ivoire, Burkina Faso, Togo, Benin, central and eastern CAR, eastern Chad, portions of Sudan and South Sudan and northern and eastern Ethiopia had below-average rainfall.

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

6. Rainfall Patterns: Last 90 Days During the past 90 days, rainfall was above-average over local areas in southern Mauritania, portions of Mali, Guinea-Conakry, Sierra Leone, Liberia, Cote d’Ivoire, western Gabon, CAR, South Sudan Republic, southern Sudan, portions of DRC, Uganda, much of Ethiopia, Kenya, parts of Somalia, and many parts of Tanzania. In contrast, parts of Senegal, eastern Burkina Faso, Ghana, Togo, Benin, Nigeria, portions of Cameroon, portions of Niger, eastern Chad, local areas in CAR, northwestern Angola, portions of DRC, Eritrea, and local areas in Ethiopia had below-average rainfall.

7. Rainfall Patterns: Last 180 Days During the past 180 days, rainfall was above-average over much of Guinea-Conakry, Sierra Leone, Liberia, Cote d’Ivoire, southern Ghana, local areas in Nigeria, many parts of CAR, Gabon, northern Congo-Brazzaville, much of DRC, South Sudan Republic, southern Sudan, Somalia, portions of Ethiopia, Zambia, northern Mozambique, portions of Botswana and Zimbabwe, and Madagascar. In contrast, Senegal, local areas in southwestern Mali, Burkina Faso, northern Ghana, Togo, Benin, much of Nigeria, Cameroon, Angola, Namibia, South Africa, southern and central Mozambique, Malawi, portions of Tanzania, local areas in DRC, northern Kenya and portions of Ethiopia had below-average rainfall.

8. Recent Rainfall Evolution Daily evolution of rainfall over the last 90 days at selected places reflects that moderate to heavy rainfall sustained moisture surpluses over parts of Sierra Leone (bottom left). In contrast, seasonal total rainfall remained below-average over portions of eastern Chad (bottom right), and eastern Sudan (top right).

9. Atmospheric Circulation:Last 7 Days The 200hpa wind anomalies (right panel) featured a broad area of westerly flow across the Greater Horn of Africa region, associated with weaker than normal Tropical Easterly Jet.

10. NCEP GEFS Model ForecastsNon-Bias Corrected Probability of precipitation exceedance Week-1: Valid 28 July – 3 Aug 2015Week-2: Valid 4 – 10 Aug 2015 For week-1 (left panel) and week-2 (right panel), there is an increased chance for rainfall to exceed 50 mm over many places in the Sahel region, northern Gulf of Guinea and Central Africa countries, and western Ethiopia.

11. Week-1 Precipitation Outlooks • There is an increased chance for above-average rainfall across southern Senegal, Guinea, Guinea-Bissau, Sierra Leone, southern and central Mali, Burkina Faso, portions of northern Cote d'Ivoire and Ghana, and southwestern Niger: 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 southern Cameroon, Gabon, Equatorial Africa, Congo and western DRC: Anomalous lower-level divergence is expected to suppress rainfall in the region. Confidence: Moderate • There is an increased chance for above-average rainfall over western Ethiopia and eastern South Sudan Republic: Anomalous lower-level wind convergence is expected to enhance rainfall in the region. Confidence: Moderate • There is an increased chance for below-average rainfall across eastern Ethiopia: Anomalous lower-level dry northeasterly flow is expected to suppress rainfall in the region. Confidence: Moderate 28 July – 03 Aug, 2015

12. Week-2 Precipitation Outlooks 04 – 10 Aug, 2015 • There is an increased chance for above-average rainfall over southern Mauritania, central and southern Mali and Burkina Faso: 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 Guinea, Sierra Leone and Liberia: Anomalous lower-level wind divergence is expected to suppress rainfall in the region. Confidence: Moderate • There is an increased chance for below-average rainfall over northern DRC, northern Congo-Brazzaville and portions of southern CAR: Anomalous lower-level divergence and upper-level convergence is expected to suppress rainfall in the region. Confidence: Moderate

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