The African Monsoon Recent Evolution and Current Status Include Week-1 and Week-2 Outlooks Update prepared by Climate Prediction Center / NCEP 26 May 2014 For more information, visit:

Outline Highlights Recent Evolution and Current Conditions NCEP GEFS Forecasts Summary

Highlights: Last 7 Days Above-average rainfall was observed over parts of the western end of West Africa, and Ethiopia, whereas suppressed rainfall prevailed over central and eastern parts of the Gulf of Guinea countries. Week-1 outlooks call for an increased chance for above-average rainfall over eastern Guinea-Conakry and the neighboring places of Mali, Cote d’Ivoire, Liberia and Sierra Leone, southeastern Nigeria, southern Cameroon, southern CAR, Equatorial Guinea, Gabon, northern DRC and western South Sudan.

Rainfall Patterns: Last 7 Days During the past seven days, above-average rainfall was observed over portions of Guinea- Conakry, western Mali, Sierra Leone, parts of Burkina Faso, DRC, Ethiopia and South Africa. In contrast, portions of eastern Guinea-Conakry, Liberia, Cote d’Ivoire, western Burkina Faso, Ghana, Togo, Benin, Nigeria, Cameroon, Equatorial Guinea, Gabon, Congo-Brazzaville, southern Chad, local areas in DRC, South Sudan and the Lake Victoria region had below- average rainfall.

Rainfall Patterns: Last 30 Days During the past 30 days, rainfall was above-average over much of Guinea-Conakry, western Mali, northern Sierra Leone, Liberia, much of Cote d’Ivoire, local areas in Ghana, Burkina Faso, Benin, portions of Nigeria, Cameroon, Gabon, Congo Brazzaville, eastern CAR, parts of DRC, South Sudan and the neighboring places of Sudan, western Ethiopia, local areas in Somalia and costal Tanzania. In contrast, eastern Ghana, local areas in Nigeria, portions of CAR and DRC, Uganda, Rwanda, Burundi, Kenya, southern Ethiopia, many parts of Tanzania, and eastern Madagascar had below-average rainfall.

Rainfall Patterns: Last 90 Days During the past 90 days, portions of Guinea Conakry, Cote d’Ivoire, Ghana, northern Benin, Gabon, eastern CAR, South Sudan, western Ethiopia, local areas in Somalia, coastal Tanzania, local areas in southern DRC, northern Zambia, eastern Namibia, much of Botswana, and local areas in South Africa received above-average rainfall. In contrast, rainfall was below-average over local areas in coastal Nigeria, DRC, many parts of Angola, Uganda, Kenya, portions of Mozambique, and much of Madagascar.

Rainfall Patterns: Last 180 Days During the past 180 days, rainfall was above-average over Liberia, Cote d’Ivoire, parts of Ghana, southern Nigeria, Gabon, local areas in Congo Brazzaville, eastern CAR, South Sudan, western Ethiopia, portions of Tanzania, southeastern Angola, eastern Namibia, Botswana, northern Zambia, much of Zimbabwe, parts of Mozambique and South Africa, and parts of Madagascar. In contrast, much of DRC, Angola, Uganda, portions of Kenya, Rwanda, Burundi, and northern Madagascar 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 resulted in accumulated moisture surpluses over parts of Gabon(bottom panel-left), and Ethiopia (top panel- right). In contrast, seasonal total rainfall remained below-average over parts of Kenya (bottom panel-right).

Atmospheric Circulation: Last 7 Days The 850Pa wind anomalies (left panel) featured anti-cyclonic flow across southern Africa countries.

NCEP GEFS Model Forecasts Non-Bias Corrected Probability of precipitation exceedance Week-1: Valid 27 May – 02 June 2014 Week-2: Valid 03 June – 09 June 2014 For week-1 (left panel) and wek-2 (right-panel), there is an increased chance for rainfall to exceed 50 mm over portions of the Gulf of Guinea, central Africa, and the Greater Horn of Africa regions.

Experimental Week-1 Precipitation Outlooks May 27 – June 02, There is an increased chance for above-average rainfall over eastern Guinea-Conakry and the neighboring places of Mali, Cote d’Ivoire, Liberia and Sierra Leone: Anomalous lower-level moist westerly flow combined with upper-level divergence is expected to enhance rainfall in the region. Confidence: Moderate 2.There is an increased chance for above-average rainfall over southeastern Nigeria, southern Cameroon, southern CAR, Equatorial Guinea, Gabon, northern DRC and western South Sudan: Anomalous lower-level moist southwesterly flow combined with upper-level divergence is expected to enhance rainfall in the region. Confidence: Moderate

Experimental Week-2 Precipitation Outlooks June 03 – June 09, There is an increased chance for below-average rainfall over southern Senegal, Gambia, Guinea-Bissau, western Guinea- Conakry, and portions of western Mali: Anomalous lower-level dry northerly flow with its associated divergence is expected to suppress rainfall in the region. Confidence: Moderate 2.There is an increased chance for above-average rainfall over southwestern Mali, eastern Guinea-Conakry, northern Cote d’Ivoire, and western Burkina Faso: Anomalous lower-level cyclonic flow with its associated convergence is expected to enhance rainfall in the region. Confidence: Moderate 3.There is an increased chance for above-average rainfall over parts of Nigeria and Cameroon: Anomalous lower-level moist southwesterly flow combined with upper-level divergence is expected to enhance rainfall in the region. Confidence: Moderate 4.There is an increased chance for below-average rainfall over parts of Chad: Anomalous lower-level dry northerly flow with its associated divergence is expected to suppress rainfall in the region. Confidence: Moderate 5.There is an increased chance for above-average rainfall over portions of Somalia, and neighboring places of Southeast Ethiopia: Anomalous lower-level onshore flow with its associated convergence is expected to enhance rainfall in the region. Confidence: Moderate

Summary During the past seven days, above-average rainfall was observed over portions of Guinea-Conakry, western Mali, Sierra Leone, parts of Burkina Faso, DRC, Ethiopia and South Africa. In contrast, portions of eastern Guinea-Conakry, Liberia, Cote d’Ivoire, western Burkina Faso, Ghana, Togo, Benin, Nigeria, Cameroon, Equatorial Guinea, Gabon, Congo-Brazzaville, southern Chad, local areas in DRC, South Sudan and the Lake Victoria region had below-average rainfall. During the past 30 days, rainfall was above-average over much of Guinea-Conakry, western Mali, northern Sierra Leone, Liberia, much of Cote d’Ivoire, local areas in Ghana, Burkina Faso, Benin, portions of Nigeria, Cameroon, Gabon, Congo Brazzaville, eastern CAR, parts of DRC, South Sudan and the neighboring places of Sudan, western Ethiopia, local areas in Somalia and costal Tanzania. In contrast, eastern Ghana, local areas in Nigeria, portions of CAR and DRC, Uganda, Rwanda, Burundi, Kenya, southern Ethiopia, many parts of Tanzania, and eastern Madagascar had below-average rainfall. During the past 90 days, portions of Guinea Conakry, Cote d’Ivoire, Ghana, northern Benin, Gabon, eastern CAR, South Sudan, western Ethiopia, local areas in Somalia, coastal Tanzania, local areas in southern DRC, northern Zambia, eastern Namibia, much of Botswana, and local areas in South Africa received above-average rainfall. In contrast, rainfall was below-average over local areas in coastal Nigeria, DRC, many parts of Angola, Uganda, Kenya, portions of Mozambique, and much of Madagascar. Week-1 outlooks call for an increased chance for above-average rainfall over eastern Guinea- Conakry and the neighboring places of Mali, Cote d’Ivoire, Liberia and Sierra Leone, southeastern Nigeria, southern Cameroon, southern CAR, Equatorial Guinea, Gabon, northern DRC and western South Sudan.