African Monsoon: Recent Evolution and Current Status

1. The African Monsoon Recent Evolution and Current StatusInclude Week-1 and Week-2 Outlooks Update prepared by Climate Prediction Center / NCEP 17 October 2011 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 • Southern Somalia, portions of Southeast Ethiopia and Northeast Kenya saw their heaviest rainfall since the start of the current rainfall season. Moderate to locally heavy rains continued to fall across central African region and western Equatorial Africa. • Week-1 outlooks call for an increased chance for above average rainfall over much of the central African and portions of the Horn of Africa countries.

4. Rainfall Patterns: Last 7 Days During the past seven days, much of the Gulf of Guinea countries, Gabon, eastern CAR, many parts of DRC, portions of Uganda, local areas of northern Tanzania, central Mozambique and portions of Madagascar received above average rainfall. Heavy rains also resulted in moisture surpluses over southern Somalia, portions of Southeast Ethiopia and eastern Kenya. Below average rainfall was observed over southern Chad, western CAR, central Angola, southeastern DRC and portions of Ethiopia.

5. Rainfall Patterns: Last 30 Days During the past 30 days, much of the Gulf of Guinea and central African countries, southern Somalia, parts of southern Ethiopia, eastern Kenya, western Uganda, Rwanda, Burundi, western Tanzania, local areas of Mozambique and Madagascar had above average rainfall. Moisture deficits were observed over southern Senegal, parts of southern Mauritania, central Nigeria, southern Chad, portions of CAR, Sudan, Ethiopia and central Angola.

6. Rainfall Patterns: Last 90 Days During the past 90 days, above average rainfall was observed across the Senegal-Mali-Guinea border, central Mali, Ghana, eastern Burkina Faso, western Chad, portions of CAR, Cameroon, Gabon, northern Congo Brazzaville, eastern DRC, Uganda, western Kenya and southern Somalia. In contrast, coastal Guinea Conakry, Sierra Leone, parts of Cote D’Ivoire, western Burkina Faso, many parts of Nigeria, eastern Sudan, Eritrea and Ethiopia had below average rainfall.

7. Rainfall Patterns: Last 180 Days During the past 180 days, rainfall was below average Southern Senegal, coastal Guinea Conakry, Sierra Leone, Cote D’Ivoire, western Niger, Much of Nigeria, portions of Cameroon, eastern Sudan, Eritrea and Ethiopia. Moisture surpluses were observed over northern Guinea Conakry, parts of southern and central Mali, Ghana, local areas of Chad and CAR, northern Congo Brazzaville, central and eastern DRC, Uganda, western Kenya, southern Somalia, southeastern Ethiopia and costal South Africa.

8. Recent Rainfall Evolution Daily evolution of rainfall over the last 90 days at selected stations reflects the gradual increase in rainfall across central and East Africa; DRC (bottom panel – left), Uganda (bottom panel-right), and the recent heavy rainfall in southern Somalia (top panel – right).

9. Atmospheric Circulation:Last 7 Days The 850hPa wind anomaly (left panel) featured westerly anomalies across Gulf of Guinea coast and easterly anomalies in the Congo Air boundary (CAB) region. The 200hpa wind anomaly (right panel) featured anomalous easterlies across East Africa and Southeast Africa.

10. NCEP GEFS Model ForecastsNon-Bias Corrected Probability of precipitation exceedance Week-1: Valid 18 – 24 October 2011Week-2: Valid 25 – 31 October 2011 For week-1 (left panel) and week-2 (right panel), there is an increased chance for rainfall to exceed 50 mm over Gulf of Guinea coast, central African region and portions of the Horn of Africa countries.

11. Experimental Week-1 Precipitation Outlooks Week-1 Outlook 18 – 24 October 2011 • There is an increased chance for above average precipitation over Southeast Nigeria, southern Cameroon, southern CAR, much of DRC, Equatorial Guinea, Gabon and Congo Brazzaville, western Uganda, Rwanda, Burundi and western Tanzania: The combination of anomalous wind convergences across central African region and the projected phase of the MJO are expected to enhance rainfall in the region. Confidence: Moderate • There is an increased chance for above average precipitation over southeastern Ethiopia, northeastern Kenya and portions of Somalia: The combination of anomalous wind convergences over the Horn of Africa and the projected phase of the MJO are expected to enhance rainfall in the region. Confidence: Moderate

12. Experimental Week-2 Precipitation Outlooks Week-2 Outlook 25 - 31 October 2011 • There is an increased chance for above average rainfall over Equatorial Guinea, Gabon, Congo Brazzaville, northern Angola and much of DRC: The projected phase of the MJO is expected to enhance rainfall in the region. Confidence: Moderate

13. Summary During the past seven days, much of the Gulf of Guinea countries, Gabon, eastern CAR, many parts of DRC, portions of Uganda, local areas of northern Tanzania, central Mozambique and portions of Madagascar received above average rainfall. Heavy rains also resulted in moisture surpluses over southern Somalia, portions of Southeast Ethiopia and eastern Kenya. Below average rainfall was observed over southern Chad, western CAR, central Angola, southeastern DRC and portions of Ethiopia. During the past 30 days, much of the Gulf of Guinea and central African countries, southern Somalia, parts of southern Ethiopia, eastern Kenya, western Uganda, Rwanda, Burundi, western Tanzania, local areas of Mozambique and Madagascar had above average rainfall. Moisture deficits were observed over southern Senegal, parts of southern Mauritania, central Nigeria, southern Chad, portions of CAR, Sudan, Ethiopia and central Angola. During the past 90 days, above average rainfall was observed across the Senegal-Mali-Guinea border, central Mali, Ghana, eastern Burkina Faso, western Chad, portions of CAR, Cameroon, Gabon, northern Congo Brazzaville, eastern DRC, Uganda, western Kenya and southern Somalia. In contrast, coastal Guinea Conakry, Sierra Leone, parts of Cote D’Ivoire, western Burkina Faso, many parts of Nigeria, eastern Sudan, Eritrea and Ethiopia had below average rainfall. Week-1 outlooks call for an increased chance for above average rainfall over much of the central African and portions of the Horn of Africa countries.