1. The African Monsoon Recent Evolution and Current Status Update prepared by Climate Prediction Center / NCEP 4 October 2010 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 Local areas in southeastern Senegal, southern Burkina Faso, and northwestern Nigeria received sizable rainfall amounts. However, the flooding threats have subsided significantly over the past week. Dry conditions prevailed over southern Sudan and much of Uganda.

4. Rainfall Patterns: Last 7 Days During the past seven days, rainfall diminished significantly over most areas in the Sahel. However, moderate to heavy rains sustained moisture surpluses in pockets over southeastern Senegal, southern Burkina Faso, and northwestern Nigeria. Rainfall was below average across most areas in the Gulf of Guinea, except for coastal Guinea and localities in along the coast line from Togo to Nigeria. Light rains prevailed over northeastern Nigeria. Also light rains fell over central Africa, except for local areas in western Central Africa and southern Congo that received substantial downpours. Dry conditions prevailed across eastern Africa.

5. Rainfall Patterns: Last 30 Days During the past 30 days, rainfall was above average over most parts of west Africa except for coastal areas in the Gulf of Guinea from Ghana to Guinea. Rainfall was also below average over central Nigeria and most areas in central Africa. Rainfall was above average parts of Ethiopia. However, dry conditions prevailed across much of eastern Africa.

6. Rainfall Patterns: Last 90 Days During the past 90 days, rainfall was above average over much of West Africa, except for local areas in the Groundnut basin of Senegal and The Gambia, Sierra Leone, southern Ghana, and much of central and eastern Nigeria. Rainfall was also above average over southern Chad and CAR, while lighter rains fell over Cameroon and DRC. Rainfall was much above average over northern Ethiopia.

7. Rainfall Patterns: Last 180 Days During the past 180 days, rainfall was above average over much of West Africa, except for local areas in the Groundnut basin of Senegal and The Gambia, Sierra Leone, southern Ghana, and much of central and eastern Nigeria. Rainfall was also above average over southern Chad and CAR, while lighter rains fell over Cameroon and DRC. Rainfall was much above average over northern Ethiopia.

8. Recent Rainfall Evolution Daily evolution of precipitation at selected stations indicates that rainfall has subsided over the western end of the Sahel following a long period of persistent rains (lower panel – left). Steady but lighter than average rains resulted in moisture deficits over Uganda (lower panel – right). Rainfall has been near average over portions of southern Sudan (upper panel – right ).

9. Atmospheric Circulation: Last 7 Days The 850 hPa wind anomaly (left panel) reflected an anomalous anticyclonic circulation over the northeastern Atlantic. The Somali Jet was stronger than normal in the western Indian Ocean and weaker than normal in the continent. The 200 hPa wind anomaly featured an anticyclonic/cyclonic couplet over northern Africa. This pattern combined with the low level conditions as featured in the 850 hPa wind anomaly may have contributed to the suppression of rainfall in East Africa and the reduction of rainfall in West Africa.

10. NCEP GEFS Model Forecasts Non-Bias Corrected Probability of precipitation exceedance Week-1: Valid 5 - 11 October Week-2: Valid 12 - 18 October, 2010 For week-1 and week-2, there is a high chance for precipitation to exceed 50 mm along the coastal areas of the Gulf of Guinea region and portions of central Africa.

11. 1. There is an increased chance for above average precipitation over the eastern parts of the Gulf of Guinea countries: Westerly to southwesterly anomalies from the Atlantic Ocean and their associated convergence across the Gulf area are expected to enhance rainfall in the region. Confidence: Moderate 2.There is an increased chance for above average rainfall over parts of eastern Africa: Southerly anomalies and their associated convergence in the northern parts of the Congo air boundary (CAB) area are expected to enhance rainfall in the region. Confidence: Moderate Experimental Week-1 Precipitation Outlooks Week-1 Outlook 28 September – 04 October, 2010

12. Experimental Week-2 Precipitation Outlooks Week-2 Outlook 12 - 18 October, 2010 1. There is an increased chance for below average rainfall over portions of central Africa: The suppressed phase of the is expected to suppress precipitation in this region. Confidence: Moderate

13. Summary During the past seven days, rainfall diminished significantly over most areas in the Sahel. However, moderate to heavy rains sustained moisture surpluses in pockets over southeastern Senegal, southern Burkina Faso, and northwestern Nigeria. Rainfall was below average across most areas in the Gulf of Guinea, except for coastal Guinea and localities in along the coast line from Togo to Nigeria. Light rains prevailed over northeastern Nigeria. Also light rains fell over central Africa, except for local areas in western Central Africa and southern Congo that received substantial downpours. Dry conditions prevailed across eastern Africa. During the past 30, rainfall was above average over most parts of west Africa except for coastal areas in the Gulf of Guinea from Ghana to Guinea. Rainfall was also below average over central Nigeria and most areas in central Africa. Rainfall was above average parts of Ethiopia. However, dry conditions prevailed across much of eastern Africa. During the past 90 days, rainfall was above average over much of West Africa, except for local areas in the Groundnut basin of Senegal and The Gambia, Sierra Leone, southern Ghana, and much of central and eastern Nigeria. Rainfall was also above average over southern Chad and CAR, while lighter rains fell over Cameroon and DRC. Rainfall was much above average over northern Ethiopia. For week-1, there is an increased chance for above average precipitation over the eastern parts of the Gulf of Guinea countries. There is also an increased chance for above average rainfall over parts of eastern Africa. For week-2, There is an increased chance for below average rainfall over portions of central Africa.