The African Monsoon Recent Evolution and Current Status

The African Monsoon Recent Evolution and Current Status Include Week-1 and Week-2 Outlooks Update prepared by Climate Prediction Center / NCEP 13 July 2015 For more information, visit: http: //www. cpc. ncep. noaa. gov/products/Global_Monsoons/African_Monsoons/precip_monitoring. shtml

Outline • Highlights • Recent Evolution and Current Conditions • NCEP GEFS Forecasts • Summary

Highlights: Last 7 Days • Above-average rainfall was observed over many places in West Africa, whereas suppressed rainfall prevailed over portions of the Central Africa and the Greater Horn of Africa countries. • Week-1 outlooks call for an increased chance for above-average rainfall over Guinea, Sierra Leone, and much of Liberia. In contrast, there is an increased chance for below-average rainfall over much of Burkina Faso, northeastern Cote d'Ivoire, portions of Ghana, Togo, Benin, western Nigeria, southwestern Niger, and northern DRC.

Rainfall Patterns: Last 7 Days During the past seven days, above-average rainfall was observed over southern Mauritania, portions of Senegal, Guinea-Bissau, Guinea-Conakry, Sierra Leone, Liberia, portions of Mali, western Burkina Faso, parts of Cote d’Ivoire and Ghana, western Niger, southern Nigeria, southern Cameroon, portions of western South Sudan Republic, and western Ethiopia. In contrast, rainfall was below-average over northern Nigeria, southern Chad, parts of CAR, northern DRC, southern Sudan, parts of South Sudan Republic, and northern and central Ethiopia.

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

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

Rainfall Patterns: Last 180 Days During the past 180 days, rainfall was above-average over much of Guinea-Bissau, Guinea. Conakry, Sierra Leone, Liberia, Cote d’Ivoire, southern Ghana, southwestern 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.

Recent Rainfall Evolution Daily evolution of rainfall over the last 90 days at selected places reflects that moderate to heavy rainfall helped to erode some of the accumulated rainfall deficits over parts of Senegal (bottom left), and sustained moisture surpluses over portions of western Ethiopia (top right). In contrast, seasonal total rainfall continued to be below-average over portions of Nigeria (bottom right).

Atmospheric Circulation: Last 7 Days The 850 hpa wind anomalies (left panel) featured a broad area of easterly flow across the Central Africa and the Gulf of Guinea countries, with its associated lower levelconvergence over the western end of West Africa, which may have contributed to the observed above-average rainfall in the region.

NCEP GEFS Model Forecasts Non-Bias Corrected Probability of precipitation exceedance Week-1: Valid 14 July – 20 July 2015 Week-2: Valid 21 July – 27 July 2015 For week-1 (left panel), there is an increased chance for rainfall to exceed 50 mm over Guinea, portions of Nigeria and Cameroon, and western Ethiopia. For week-2 (right panel), there is an increased chance for rainfall to exceed 50 mm over many places in West Africa and western Ethiopia.

Week-1 Precipitation Outlooks 14 – 20 July, 2015 1. There is an increased chance for above-average rainfall over Guinea, Sierra Leone, and much of Liberia: Anomalous lower-level convergence is expected to enhance rainfall in the region. Confidence: Moderate 2. There is an increased chance for below-average rainfall over much of Burkina-Faso, northeastern Cote d'Ivoire, portions of Ghana, Togo, Benin, western Nigeria and southwestern Niger: Anomalous lower-level divergence is expected to suppress rainfall in the region. Confidence: Moderate 3. There is an increased chance for below-average rainfall over northern DRC: Anomalous lower-level divergence is expected to suppress rainfall in the region. Confidence: Moderate

Week-2 Precipitation Outlooks 21 - 27 July, 2015 1. There is an increased chance for above-average rainfall over southern Mali, portions of northern Guinea, northern Cote d'Ivoire, northern Ghana, much of Burkina Faso, southern Niger, northern Togo, northern Benin, portions of Nigeria, and northern Cameroon: A broad area of anomalous lower-level convergence is expected to enhance rainfall in the region. Confidence: Moderate 2. There is an increased chance for below-average rainfall over northern DRC and Uganda: An anomalous area of lower-level divergence and upper-level convergence is expected to suppress rainfall in the region. Confidence: Moderate

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