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 19 May 2014 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 • Suppressed rainfall prevailed over much of Nigeria, Burkina Faso, Ghana, and the Lake Victoria region, whereas above average rainfall was observed over much of Guinea-Conakry, Liberia, and portions of the central African countries. • Week-1 outlooks call for an increased chance for above-average rainfall over parts of Guinea-Conakry, Sierra Leone, Liberia, many parts of Ethiopia, and coastal Kenya and Tanzania. In contrast, there is an increased chance for below-average rainfall over parts of Nigeria.

4. Rainfall Patterns: Last 7 Days During the past seven days, above-average rainfall was observed over much of Guinea-Conakry, northern Sierra Leone, Liberia, local areas in Mali and Cote d’Ivoire, southern Cameroon, Gabon, Congo-Brazzaville, eastern CAR, portions of DRC and South Sudan, local areas in Ethiopia and Somalia, and coastal Kenya and Tanzania. In contrast, portions of Burkina Faso and Ghana, much of Nigeria, northern Cameroon, Uganda, northern Tanzania, Rwanda, Burundi, Kenya, and portions of Ethiopia had below-average rainfall.

5. Rainfall Patterns: Last 30 Days During the past 30 days, rainfall was above-average over eastern Guinea, northern Sierra Leone, Liberia, much of Cote d’Ivoire, parts of 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 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.

6. 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.

7. Rainfall Patterns: Last 180 Days During the past 180 days, rainfall was above-average over Liberia, Cote d’Ivoire, Ghana, southern Nigeria, Cameroon, 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, and northern Madagascar 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 resulted in accumulated moisture surpluses over parts of Cote d’Ivoire (bottom panel-left), and South Sudan (top panel-right). In contrast, seasonal total rainfall remained below-average over parts of Kenya (bottom panel-right).

9. Atmospheric Circulation:Last 7 Days The 850Pa wind anomalies (left panel) featured westerlies across equatorial eastern Atlantic. Upper-level anti-cyclonic anomaly was observed across Northeast Atlantic and the neighboring places of Europe and Northwest Africa (right panel).

10. NCEP GEFS Model ForecastsNon-Bias Corrected Probability of precipitation exceedance Week-1: Valid 20 – 26 May 2014Week-2: Valid 27 May – 02 June 2014 For week-1 (left panel) and wek-2 (right-panel), there is an increased chance for rainfall to exceed 50 mm over western end of the Gulf of Guinea region, Cameroon, Gabon, Northeast DRC, western Kenya and Ethiopia.

11. Experimental Week-1 Precipitation Outlooks • There is an increased chance for above-average rainfall over Guinea-Conakry, Sierra Leone, and Liberia: Anomalous lower-level moist southwesterly flow combined with upper-level divergence is expected to enhance rainfall in the region. Confidence: Moderate • There is an increased chance for below-average rainfall over northern Nigeria: Anomalous lower-level dry northerly flow with its associated divergence is expected to suppress rainfall in the region. Confidence: Moderate • There is an increased chance for above-average rainfall over western Ethiopia: Anomalous lower-level convergence, and interaction between mid-latitude and tropical systems across Northeast Africa is expected to enhance rainfall in the region. Confidence: Moderate • There is an increased chance for above-average rainfall along coastal Kenya and Tanzania: Anomalous onshore flow with its associated convergence is expected to enhance rainfall in the region. Confidence: Moderate May 20 – May 26, 2014

12. Experimental Week-2 Precipitation Outlooks May 27 – June 02, 2014 • There is an increased chance for above-average rainfall over much of South Sudan: Anomalous lower-level convergence combined with upper-level divergence is expected to enhance rainfall in the region. Confidence: Moderate • There is an increased chance for above-average rainfall over portions of southern Somalia and coastal Kenya: Anomalous onshore flow with its associated convergence is expected to enhance rainfall in the region. Confidence: Moderate

13. Summary During the past seven days, above-average rainfall was observed over much of Guinea-Conakry, northern Sierra Leone, Liberia, local areas in Mali and Cote d’Ivoire, southern Cameroon, Gabon, Congo-Brazzaville, eastern CAR, portions of DRC and South Sudan, local areas in Ethiopia and Somalia, and coastal Kenya and Tanzania. In contrast, portions of Burkina Faso and Ghana, much of Nigeria, northern Cameroon, Uganda, northern Tanzania, Rwanda, Burundi, Kenya, and portions of Ethiopia had below-average rainfall. During the past 30 days, rainfall was above-average over eastern Guinea, northern Sierra Leone, Liberia, much of Cote d’Ivoire, parts of 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 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 parts of Guinea-Conakry, Sierra Leone, Liberia, many parts of Ethiopia, and coastal Kenya and Tanzania. In contrast, there is an increased chance for below-average rainfall over parts of Nigeria.