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 14 November 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 • Weekly total rainfall exceeded 120mm over parts of Gabon, southern Congo and northwestern DRC, while much of the southern Africa countries received little or no rainfall. • Above average rainfall continued across many places of the Horn of Africa. • Week-1 outlooks call for an increased chance for above average rainfall over southern Gabon, southern Congo, many parts of DRC, western Angola, portions of southern Somalia, southeastern Kenya, eastern Tanzania, eastern Botswana, much of Zimbabwe, central and southern Mozambique, northeastern South Africa and Swaziland.

4. Rainfall Patterns: Last 7 Days During the past seven days, above average rainfall was observed over portions over southern Gabon, Congo, western and southern DRC, northern Angola, northern Uganda, northern and eastern ends of Tanzania, many parts of Kenya, southern Somalia, portions of Ethiopia and Madagascar. In contrast, moisture deficits prevailed over many places of the Southern Africa countries, parts of Cameroon, CAR and southern parts of South Sudan Republic.

5. Rainfall Patterns: Last 30 Days During the past 30 days, above average rainfall was observed across coastal Gulf of Guinea, portions of Cote D’Ivoire, western CAR, Congo, much of DRC, South Sudan Republic, Uganda, much of Kenya, portions of Ethiopia, southern Somalia and parts of Madagascar, with rainfall surpluses exceeding 100mm over southern Congo, southwestern DRC, northern Angola, parts of Uganda, many parts of Uganda, southern Somalia and southern Ethiopia. Parts of Senegal, Guinea Bissau, southwestern Mali, central and southeastern Nigeria, Cameroon, eastern CAR, local areas of central DRC, southern Angola, northeastern Namibia, Botswana, central Zimbabwe, many parts of South Africa and Lesotho had below average rainfall.

6. Rainfall Patterns: Last 90 Days During the past 90 days, below average rainfall was observed over southern Senegal, Guinea Bissau, coastal areas of Guinea, central Nigeria, western Ethiopia and parts of Angola. Eastern Guinea, portions of Liberia, Cote D’Ivoire, southern Ghana, southern, Togo and Benin, local areas of Nigeria, central and eastern Cameroon, CAR, Gabon, Congo, much of DRC, Uganda, parts of South Sudan Republic, much of Kenya, southern Ethiopia, central and southern Somalia, costal Tanzania, local areas of central Mozambique and Madagascar received above average rainfall.

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

8. Recent Rainfall Evolution Daily evolution of rainfall over the last 90 days at selected stations reflects the suppressed rainfall over central Angola, despite the recent increase in rainfall over the region (bottom panel-left). Rainfall continued to be suppressed over many parts of South Africa (bottom panel – right). In contrast, another week of heavy rainfall sustained moisture surpluses in the GHA region (top panel – right).

9. Atmospheric Circulation:Last 7 Days The 850hPa wind anomaly (left panel) featured convergence between northwesterly and southwesterly anomalies across the GHA region, which may have contributed to the observed moisture surplus in this region. The 200hpa wind anomaly (right panel) featured strong easterly anomalies in the region between Madagascar and Angola, and stronger than normal Subtropical Westerly Jet across southern Atlantic Ocean and the southern end of South Africa..

10. NCEP GEFS Model ForecastsNon-Bias Corrected Probability of precipitation exceedance Week-1: Valid 15 – 21 November 2011Week-2: Valid 22 – 28 November 2011 For week-1 (left panel) and week-2 (right panel), there is an increased chance for rainfall to exceed 50 mm over Equatorial Guinea, Gabon, Congo, much of DRC, northern Angola, western Zambia and eastern Kenya.

11. Experimental Week-1 Precipitation Outlooks Week-1 Outlook 15 – 21 November 2011 • There is an increased chance for above average precipitation over southern Gabon, southern Congo, much of DRC and Angola: The combination of moist westerly anomalies from the Atlantic Ocean and the projected phase of the MJO is expected to enhance rainfall in the region. Confidence: Moderate • There is an increased chance for above average rainfall over portions of southern Somalia, southeastern Kenya and eastern Tanzania: Moist easterly anomalies from the Indian Ocean, with their convergence across coastal East Africa are expected to enhance rainfall in the region. Confidence: Moderate • There is an increased chance for above average precipitation over eastern Botswana, much of Zimbabwe, central and southern Mozambique, northeastern South Africa and Swaziland: Anomalous cyclonic shear across Southeast Africa is expected to enhance rainfall in the region. Confidence: Moderate

12. Experimental Week-2 Precipitation Outlooks Week-2 Outlook 22 – 28 November 2011 • There is an increased chance for above average rainfall over Equatorial Guinea, Gabon, Congo Brazzaville, much of Angola and DRC: The projected phase of the MJO is expected to enhance rainfall in the region. Confidence: Moderate

13. Summary During the past seven days, above average rainfall was observed over southern Gabon, Congo, western and southern DRC, northern Angola, northern Uganda, northern and eastern ends of Tanzania, many parts of Kenya, southern Somalia, portions of Ethiopia and Madagascar. In contrast, moisture deficits prevailed over many places of the Southern Africa countries, parts of Cameroon, CAR and southern parts of South Sudan Republic. During the past 30 days, above average rainfall was observed across coastal Gulf of Guinea, portions of Cote D’Ivoire, western CAR, Congo, much of DRC, South Sudan Republic, Uganda, much of Kenya, portions of Ethiopia, southern Somalia and parts of Madagascar, with rainfall surpluses exceeding 100mm over southern Congo, southwestern DRC, northern Angola, parts of Uganda, many parts of Uganda, southern Somalia and southern Ethiopia. Parts of Senegal, Guinea Bissau, southwestern Mali, central and southeastern Nigeria, Cameroon, eastern CAR, local areas of central DRC, southern Angola, northeastern Namibia, Botswana, central Zimbabwe, many parts of South Africa and Lesotho had below average rainfall. During the past 90 days, below average rainfall was observed over southern Senegal, Guinea Bissau, coastal areas of Guinea, central Nigeria, western Ethiopia and parts of Angola. Eastern Guinea, portions of Liberia, Cote D’Ivoire, southern Ghana, southern, Togo and Benin, local areas of Nigeria, central and eastern Cameroon, CAR, Gabon, Congo, much of DRC, Uganda, parts of South Sudan Republic, much of Kenya, southern Ethiopia, central and southern Somalia, costal Tanzania, local areas of central Mozambique and Madagascar received above average rainfall. Week-1 outlooks call for an increased chance for above average rainfall over southern Gabon, southern Congo, many parts of DRC, western Angola, portions of southern Somalia, southeastern Kenya, eastern Tanzania, eastern Botswana, much of Zimbabwe, central and southern Mozambique, northeastern South Africa and Swaziland.