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 08 April 2013 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 • Another week of heavy rainfall sustained moisture surpluses over portions of Ethiopia, Somalia, much of Kenya and northern Tanzania. • Southern Gabon, southern Congo, Angola, and western DRC also continued to receive moderate to locally heavy rainfall. • Week-1 outlooks call for an increased chance for above-average rainfall over portions of Tanzania and Kenya, Burundi, Rwanda, southern Uganda, eastern DRC, portions of southern Somalia, and southern Ethiopia. In contrast, there is an increased chance for below-average rainfall over parts of South Sudan, Central African Republic, and northern DRC.

4. Rainfall Patterns: Last 7 Days During the past seven days, above-average rainfall was observed over local areas in Sierra Leone and Liberia, southern Benin, parts of CAR, southern Gabon, southern Congo, portions of DRC, Angola, Ethiopia, much of Kenya and Tanzania, parts of Somalia, local areas in South Sudan, and parts of South Africa. In contrast, southern Ghana, parts of Nigeria, local areas in CAR and Gabon, Equatorial Guinea, northern Congo, portions of DRC and Angola, much of Zambia, southern Tanzania, northern Mozambique and much of Madagascar had below-average rainfall.

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

6. Rainfall Patterns: Last 90 Days During the past 90 days, local areas in Togo, Benin and Nigeria, portions of Cameroon, Equatorial Guinea, western Gabon, southern CAR, parts of Angola and DRC, southeastern Ethiopia, central and southern Mozambique, local areas in southern Zimbabwe, northeastern South Africa, southern Mozambique and southern Madagascar received above-average rainfall. In contrast, rainfall was below-average over southern and eastern Angola, local areas in DRC, portions of Zambia, many parts of Namibia, Botswana, southern Tanzania, northern Mozambique and northern Madagascar.

7. Rainfall Patterns: Last 180 Days During the past 180 days, rainfall was above-average over Guinea, Sierra Leone, Liberia, Cote d’Ivoire, Ghana, portions of Nigeria, Cameroon, and CAR, much of Gabon, portions of DRC, local areas in Angola, Uganda, local areas in Kenya and Ethiopia, parts of Zambia Mozambique, northeastern South Africa, and southern Madagascar. Portions of DRC, local areas in Ethiopia and Tanzania, much of Namibia, parts of Botswana and South Africa, and northern Madagascar had below-average rainfall.

8. Recent Rainfall Evolution Daily evolution of rainfall over the last 90 days at selected places reflects moisture deficits that prevailed over parts of southern Angola (bottom panel-left). The recent moderate to heavy rainfall sustained rainfall surpluses over southern Ethiopia (top panel-right) and Kenya (bottom panel right).

9. Atmospheric Circulation:Last 7 Days The 850hPa wind anomaly (left panel) featured lower-level wind convergence near the Horn of Africa, which may have contributed to the observed rainfall surpluses portions of Tanzania, Kenya, southern Ethiopia and Somalia.

10. NCEP GEFS Model ForecastsNon-Bias Corrected Probability of precipitation exceedance Week-1: Valid April 9 – April 15, 2013Week-2: Valid April 16 – April 22, 2013 For week-1 (left panel), there is an increased chance for rainfall to exceed 50 mm over Northeast Angola, southern and eastern DRC, Rwanda, Burundi, parts of Uganda, Tanzania, Kenya, southern Ethiopia and Somalia. The probability of exceedance tends to decrease over Kenya, Ethiopia and Somalia during week-2 (right panel).

11. Experimental Week-1 Precipitation Outlooks 09 April – 15 April 2013 • There is an increased chance for below-average rainfall over South Sudan, eastern CAR, and northern DRC: Dry and anomalous lower-level northerly winds are expected to suppress rainfall in the region. Confidence: Moderate • There is an increased chance for above-average rainfall over portions of Tanzania, southwestern Kenya, Burundi, Rwanda, southern Uganda and eastern DRC: Anomalous lower-level westerly wind and its associated convergence is expected to enhance rainfall in the region. Confidence: Moderate • There is an increased chance for above-average rainfall over portions of southern Somalia, southern Ethiopia and northeastern Kenya: Anomalous lower-level convergence and upper-level divergence is expected to enhance rainfall in the region. Confidence: Moderate

12. Experimental Week-2 Precipitation Outlooks 16 April – 22 April 2013 • There is an increased chance for below-average rainfall over northern DRC, northern Uganda, southern South Sudan, and southern CAR: Anomalous northerly winds are expected to suppress rainfall in the region. Confidence: Moderate • There is an increased chance for above-average rainfall over portions of Tanzania, southwestern Kenya, Burundi, Rwanda, southern Uganda and eastern DRC: Anomalous lower-level westerly wind and 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 local areas in Sierra Leone and Liberia, southern Benin, parts of CAR, southern Gabon, southern Congo, portions of DRC, Angola, Ethiopia, much of Kenya and Tanzania, parts of Somalia, local areas in South Sudan, and parts of South Africa. In contrast, southern Ghana, parts of Nigeria, local areas in CAR and Gabon, Equatorial Guinea, northern Congo, portions of DRC and Angola, much of Zambia, southern Tanzania, northern Mozambique and much of Madagascar had below-average rainfall. During the past 30 days, above-average rainfall was observed over parts of Cote d’Ivoire, northern Ghana, Togo, Benin, local areas in Nigeria, much of Cameroon, western Gabon, parts of CAR, local areas in Congo, many parts of DRC, western and northern Angola, Uganda, southern Ethiopia, Somalia, Kenya, parts of Tanzania, local areas in Zimbabwe and Botswana, parts of South Africa, and local areas in Namibia and parts of Madagascar. In contrast, southern Ghana, eastern Gabon, local areas in DRC and Congo, western Ethiopia, southern Tanzania, southern and eastern Angola, Namibia, much of of Zambia, Botswana, Zimbabwe, much of Mozambique, and portions of Madagascar received below-average rainfall. During the past 90 days, local areas in Togo, Benin and Nigeria, portions of Cameroon, Equatorial Guinea, western Gabon, southern CAR, parts of Angola and DRC, southeastern Ethiopia, central and southern Mozambique, local areas in southern Zimbabwe, northeastern South Africa, southern Mozambique and southern Madagascar received above-average rainfall. In contrast, rainfall was below-average over southern and eastern Angola, local areas in DRC, portions of Zambia, many parts of Namibia, Botswana, southern Tanzania, northern Mozambique and northern Madagascar. Week-1 outlooks call for an increased chance for above-average rainfall over portions of Tanzania and Kenya, Burundi, Rwanda, southern Uganda, eastern DRC, portions of southern Somalia, and southern Ethiopia. In contrast, there is an increased chance for below-average rainfall over parts of South Sudan, Central African Republic, and northern DRC.