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 23 May 2016 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 surpluses exceeded 200mm over portions of western Ethiopia. • Above-average rainfall was observed over local areas in West and Central Africa, whereas suppressed rainfall prevailed over Equatorial Guinea, Gabon, central DRC and Uganda. • Week-1 outlooks call for an increased chance for above-average rainfall over Liberia, Cote d’Ivoire, Ghana, southern Togo, Benin, southern Benin, portions of Nigeria, Cameroon, CAR and western South Sudan. In contrast, there is an increased chance for below-average rainfall over northern Guinea, parts of southern Mali, and central DRC.

4. Rainfall Patterns: Last 7 Days During the past seven days, above-average rainfall was observed over local areas in Guinea and Mali, southern Cote d’Ivoire, Ghana, local areas in Niger, parts of Nigeria, Cameroon and Chad, local areas in Congo-Brazzaville, northwestern DRC, southern Sudan, much of South Sudan Republic, western Ethiopia, and southwestern Kenya. In contrast, parts of Guinea, Sierra Leone, Liberia, Burkina Faso, portions of Nigeria and Cameroon, Equatorial guinea, much of Gabon, southern Congo-Brazzaville, central and eastern DRC, Uganda, and portions of Ethiopia had below-average rainfall.

5. Rainfall Patterns: Last 30 Days During the past 30 days, rainfall was above-average over portions of Guinea, southern Mali, Burkina Faso, portions of Ghana, southern Togo, central Benin, parts of Nigeria and Cameroon, Equatorial Guinea, Gabon, portions of CAR, South Sudan, Congo Brazzaville, portions DRC, Uganda, much of Ethiopia and Somalia, Djibouti, Tanzania, and South Africa. In contrast, below-average was observed over Liberia, much of Cote d’Ivoire, parts of Ghana and Nigeria, northwestern Angola, portions of DRC and CAR, local areas in southern Ethiopia and southern Kenya, northeastern Tanzania, and portions of Madagascar.

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

7. Rainfall Patterns: Last 180 Days During the past 180 days, rainfall was above-average over portions of eastern Mauritania, Mali, northern Guinea Conakry, Burkina Faso, Togo, Benin, western Niger, local areas in Nigeria, Cameroon, CAR, South Sudan, Ethiopia, portions of Somalia, local areas in Gabon, portions of DRC, eastern Uganda, Kenya, Tanzania, Rwanda, Burundi, northern Mozambique, portions of Zambia, northern Botswana, portions of Madagascar, and southwestern South Africa. In contrast, below-average rainfall was observed over portions of southern Guinea Conakry, Sierra Leone, Liberia, much of Cote d’Ivoire, Ghana, southern Nigeria, Equatorial Guinea, portions of Gabon, central Congo Brazzaville, portions of DRC, local areas in southern Ethiopia and southern Somalia, local areas in northern and eastern Kenya, Angola, much of Namibia, eastern Zambia, southern Malawi, portions of Zimbabwe, central and southern Mozambique, portions of South Africa, and coastal Madagascar.

8. Recent Rainfall Evolution Daily evolution of rainfall over the last 90 days at selected locations shows sustained rainfall deficits over parts of Ghana (bottom left) and Uganda (bottom right). Moderate to heavy rainfall sustained moisture surpluses over western Ethiopia (top right).

9. Atmospheric Circulation:Last 7 Days At 700hPa level (left panel), anomalous lower-level westerly flow from the Atlantic Ocean into the Equatorial Africa with its associated cyclonic turning may have contributed to the observed rainfall surpluses over West and Central African countries.

10. NCEP GEFS Model ForecastsNon-Bias Corrected Probability of precipitation exceedance Week-1: Valid 24 – 30 May, 2016 Week-2: Valid 31 May – 06 June, 2016 For week-1 (left panel), there is an increased chance for weekly rainfall totals to exceed 50mm over local areas in Guinea, Ghana, coastal Nigeria, Cameroon, northern and northeastern DRC and western Ethiopia.

11. Week-1 Precipitation Outlooks 24 – 30 May, 2016 • There is an increased chance for below-average rainfall over northern Guinea and portions of southern Mali: An area of lower-level divergence and upper-level convergence is expected to suppress rainfall. Confidence: Moderate • There is an increased chance for above-average rainfall across Liberia, Cote d’Ivoire, Ghana, southern Togo, Benin, portions of Nigeria, CAR and western South Sudan: Stronger than normal westerly flow, combined with anomalous lower-level convergence and upper-level divergence across West and Central Africa is expected to enhance rainfall in the region. Confidence: Moderate • There is an increased chance for below-average rainfall over parts of central DRC: An area of anomalous lower-level divergence and upper-level convergence is expected to suppress rainfall in the region. Confidence: Moderate

12. Week-2 Precipitation Outlooks 31 May – 06 June, 2016 • There is an increased chance for above-average rainfall over much of Guinea, Sierra Leone, and western Liberia: Stronger than normal southwesterly flow, combined with anomalous lower-level convergence and upper-level divergence is expected to enhance rainfall in the region. Confidence: Moderate • There is an increased chance for above-average rainfall over eastern Nigeria and Cameroon: An area of anomalous lower-level convergence and upper-level divergence is expected to enhance rainfall in the region. Confidence: Moderate • There is an increased chance for below-average rainfall over central and northern DRC, parts of South Sudan and Uganda: An area of anomalous lower-level divergence and upper-level convergence is expected to suppress rainfall in the region. Confidence: Moderate

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