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 November 2012 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 • Rainfall deficits were observed over the Lake Victoria region and many places of the Southern Africa region. • Weekly total rainfall exceeded 75mm over portions of western Equatorial Africa, including Angola, and local areas in DRC. • Week-1 outlooks call for an increased chance for above-average rainfall over Angola, and the neighboring areas of Zambia, Botswana and Namibia, eastern DRC, Uganda, Rwanda, Burundi, Tanzania, parts of Kenya, eastern South Africa, Lesotho and Swaziland. In contrast, there is an increased chance for below-average rainfall over much of Zimbabwe and the neighboring areas of Mozambique.

4. Rainfall Patterns: Last 7 Days During the past seven days, above-average rainfall was observed over western Guinea, Sierra Leone, southern Cameroon, Equatorial Guinea, Gabon, local areas in CAR, parts of Angola and DRC, local areas in Namibia and Tanzania, Central Kenya, Southern Ethiopia, southern Somalia, and southern Madagascar. In contrast, local areas in Gabon and Congo, local areas in Angola and DRC, much of Uganda, parts of Kenya, Tanzania, Zambia, Zimbabwe, Botswana, portions of South Africa, Mozambique and northern Madagascar received below average rainfall.

5. Rainfall Patterns: Last 30 Days During the past 30 days, above-average rainfall was observed over Morocco, northern Algeria, Guinea, Sierra Leone, Liberia, parts of Cote d’Ivoire, Ghana, local areas in Burkina Faso, Togo, parts of Benin, local areas in Nigeria, Equatorial Guinea, local areas in Gabon, CAR, many parts of DRC, portions of Angola, northern Zambia, South Sudan, parts of Ethiopia, Uganda, western and southern Kenya, much of Tanzania, local areas in Mozambique, coastal South Africa and much of Madagascar. In contrast, local areas in Nigeria, portions of Cameroon and Gabon, Congo, local areas in DRC, southern Angola, local areas in Namibia and Botswana, portions of South Africa, Ethiopia, northern and eastern Kenya, and southern Somalia received below average rainfall.

6. Rainfall Patterns: Last 90 Days During the past 90 days, southern Mauritania, local areas in Senegal, much of Guinea, Guinea-Bissau, Sierra Leone, Mali, Liberia, local areas in Burkina Faso, Nigeria, southern Chad, Cameroon, portions of CAR and DRC, South Sudan, portions of Angola, Uganda, Kenya, portions of Ethiopia, eastern South Africa and portions of Madagascar had above average rainfall. In contrast, rainfall was below average over local areas in Ethiopia and Eritrea.

7. Rainfall Patterns: Last 180 Days During the past 180 days, rainfall was above-average over local areas in Senegal, southern Mauritania, many parts of Mali, Guinea Bissau, Guinea, Sierra Leone, local areas in Liberia, Cote d’Ivoire, Burkina Faso, Ghana and Benin, portions of Nigeria and Niger, southern Chad, northern Cameroon, CAR, portions of Gabon and DRC, northern Angola, South Sudan, Uganda, western Kenya, local areas in Ethiopia, eastern South Africa and local areas in Madagascar. Eastern Liberia, southern Cote d’Ivoire, southern Benin, portions of Nigeria, southern Cameroon, Equatorial Guinea, northern Gabon, Congo, portions of Ethiopia and Eritrea had below average rainfall.

8. Recent Rainfall Evolution Daily evolution of rainfall over the last 90 days at selected stations reflects that rainfall remained above average over Gabon (bottom panel – left). Portions of Southeast Ethiopia received rainfall that helped to erode some of the rainfall deficits (top panel – right). Suppressed rainfall that prevailed over Southern Africa region led to moisture deficits over portions of Zimbabwe (bottom panel –right).

9. Atmospheric Circulation:Last 7 Days The 850hPa wind anomaly (left panel) featured anomalous lower level easterlies across Central African region, which may have contributed to the increase in rainfall across western Equatorial African region, and a decrease in rainfall in the Lake Victoria region. Anomalous lower-level anticyclonic was observed over Southern African region, which may have contributed to the suppressed rainfall in the region.

10. NCEP GEFS Model ForecastsNon-Bias Corrected Probability of precipitation exceedance Week-1: Valid 20 – 26 November 2012Week-2: Valid 27 – 03 December 2012 For week-1 (left panel), there is an increased chance for rainfall to exceed 50 mm across western Equatorial Africa, including Angola, DRC, the Lake Victoria region, eastern South Africa and Madagascar. For week-2 (right-panel), the moderate to higher probabilities of exceedance are expected to expand towards Southeast Africa and portions of the Horn of Africa.

11. Experimental Week-1 Precipitation Outlooks 20 – 26 November 2012 • There is an increased chance for above average rainfall over parts of Angola, and the neighboring areas of Zambia, Botswana and Namibia: Anomalous lower-level wind convergence is expected to enhance rainfall in the region. Confidence: Moderate • There is an increased chance for above average rainfall over eastern DRC, Uganda, Rwanda, Burundi, Tanzania and parts of Kenya: Stronger than normal lower-level wind convergence in the Congo Basin is expected to enhance rainfall in the region. Confidence: Moderate • There is an increased chance for below average rainfall over much of Zimbabwe and the neighboring areas of Mozambique: Anomalous lower level divergence is expected to suppress rainfall in the region. Confidence: Moderate • There is an increased chance for above average rainfall over eastern South Africa, Lesotho and Swaziland: Anomalous lower level southerlies and their associated convergence are expected to enhance rainfall in the region.. Confidence: Moderate

12. Experimental Week-2 Precipitation Outlooks 27 November – 03 December 2012 • There is an increased chance for above average rainfall over Equatorial Guinea, Gabon, Congo, western DRC and northern Angola: Anomalous lower level easterlies from the Congo Basin are expected to enhance rainfall in the region. Confidence: Moderate • There is an increased chance for above average rainfall over southern Angola and northern Namibia: Anomalous lower-level wind convergence is expected to enhance rainfall in the region. Confidence: Moderate • There is an increased chance for above average rainfall over eastern Zimbabwe, parts of Mozambique, and the neighboring areas of South Africa: Anomalous southeasterlies and their associated convergence are expected to enhance rainfall in the region. Confidence: Moderate • There is an increased chance for above average rainfall over Eastern Ethiopia and the neighboring areas of Somalia: Anomalous southeasterlies from the Indian Ocean are expected to enhance rainfall in the region. Confidence: Moderate

13. Summary During the past seven days, above-average rainfall was observed over western Guinea, Sierra Leone, southern Cameroon, Equatorial Guinea, Gabon, local areas in CAR, parts of Angola and DRC, local areas in Namibia and Tanzania, Central Kenya, Southern Ethiopia, southern Somalia, and southern Madagascar. In contrast, local areas in Gabon and Congo, local areas in Angola and DRC, much of Uganda, parts of Kenya, Tanzania, Zambia, Zimbabwe, Botswana, portions of South Africa, Mozambique and northern Madagascar received below average rainfall. During the past 30 days, above-average rainfall was observed over Morocco, northern Algeria, Guinea, Sierra Leone, Liberia, parts of Cote d’Ivoire, Ghana, local areas in Burkina Faso, Togo, parts of Benin, local areas in Nigeria, Equatorial Guinea, local areas in Gabon, CAR, many parts of DRC, portions of Angola, northern Zambia, South Sudan, parts of Ethiopia, Uganda, western and southern Kenya, much of Tanzania, local areas in Mozambique, coastal South Africa and much of Madagascar. In contrast, local areas in Nigeria, portions of Cameroon and Gabon, Congo, local areas in DRC, southern Angola, local areas in Namibia and Botswana, portions of South Africa, Ethiopia, northern and eastern Kenya, and southern Somalia received below average rainfall. During the past 90 days, southern Mauritania, local areas in Senegal, much of Guinea, Guinea-Bissau, Sierra Leone, Mali, Liberia, local areas in Burkina Faso, Nigeria, southern Chad, Cameroon, portions of CAR and DRC, South Sudan, portions of Angola, Uganda, Kenya, portions of Ethiopia, eastern South Africa and portions of Madagascar had above average rainfall. In contrast, rainfall was below average over local areas in Ethiopia and Eritrea. Week-1 outlooks call for an increased chance for above-average rainfall over Angola, and the neighboring areas of Zambia, Botswana and Namibia, eastern DRC, Uganda, Rwanda, Burundi, Tanzania, parts of Kenya, eastern South Africa, Lesotho and Swaziland. In contrast, there is an increased chance for below-average rainfall over much of Zimbabwe and the neighboring areas of Mozambique.