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 03 January 2012 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 • Heavy rainfall in excess of 120mm was observed across portions of eastern Zimbabwe. • Suppressed rainfall prevailed over much of Tanzania and neighboring areas after several weeks of enhanced rain. • Week-1 outlooks call for an increased chance for above average rainfall over southeastern Africa including Madagascar, while suppressed rainfall is expected across portions of southern Africa countries.

4. Rainfall Patterns: Last 7 Days During the past seven days, below average rainfall was observed over Equatorial Guinea, much of Gabon, southern and central Congo, many parts of DRC, northern Angola, northeastern Zambia, Malawi, Burundi, portions of Uganda and Rwanda, southwestern Kenya, many parts of Tanzania, northern and southern Mozambique, local areas in northeastern South Africa and western Madagascar. In contrast, moisture surpluses were observed over local areas in northern DRC and eastern Tanzania, central and southern Angola, northeastern Namibia, local areas in Botswana and South Africa, many parts of Zimbabwe and Zambia, local areas in southern Mozambique and eastern Madagascar.

5. Rainfall Patterns: Last 30 Days During the past 30 days, southern Cameroon, Gabon, Equatorial Guinea, much of Congo, many parts of DRC, portions of northern and western Angola, eastern Zambia, Malawi, portions of South Africa, Swaziland, many parts of Mozambique and Madagascar, Kenya, Uganda, southern Somalia and southern Ethiopia received below average rainfall. In contrast, above average rainfall was observed over local areas in central Congo, portions of southern DRC, many parts of Angola, western Zambia, northern Namibia, Botswana, many parts of Zimbabwe and much of Tanzania.

6. Rainfall Patterns: Last 90 Days During the past 90 days, coastal Cote D’Ivoire, central Congo, local areas in CAR, western and southern DRC, Uganda, much of Tanzania, Kenya, southern Somalia, southern Ethiopia, western Zambia, portions of Angola, northern Botswana and local areas in eastern Zimbabwe received above average rainfall. Below average rainfall was observed across southern Cameroon, much of Gabon, Equatorial Guinea, local areas in DRC, portions of Mozambique, many parts of South Africa and Madagascar.

7. Rainfall Patterns: Last 180 Days During the past 180 days, rainfall was above average across northern Guinea, central Mali, eastern Ghana, local areas in Chad, parts of Congo, CAR, portions of DRC, southern South Sudan Republic, Uganda, much of Kenya, Rwanda, Burundi, southern Ethiopia, central and southern Somalia, many parts of Tanzania, northern and eastern Angola, western Zambia and northern Botswana. Moisture deficits were observed across southern Mauritania, southern Senegal, coastal Guinea Conakry, Sierra Leone, local areas in Liberia, western Burkina Faso and western Niger, many parts of Nigeria, southern Cameroon, northern Gabon, eastern Sudan, Eritrea, Ethiopia, portions of South Africa, northern Mozambique, southern Malawi and Madagascar.

8. Recent Rainfall Evolution Daily evolution of rainfall over the last 90 days at selected stations reflects rainfall deficits that prevailed over northeastern South Africa (bottom panel-left) and southern Malawi(top panel – right). The recent heavy rainfall sustained above average rainfall across portions of Zimbabwe(bottom panel – right).

9. Atmospheric Circulation:Last 7 Days The 850hPa wind anomaly (left panel) featured anomalous moist westerlies, with their convergence across Angola and neighboring areas may have contributed to the observed moisture surpluses in the region. Anomalous southerlies were also observed across southeastern Africa including Madagascar. The 200hPa wind anomaly (right panel) featured stronger than normal sub-tropical westerly jet across northwestern Africa.

10. NCEP GEFS Model ForecastsNon-Bias Corrected Probability of precipitation exceedance Week-1: Valid 04 – 10 January 2012Week-2: Valid 11 – 17 January 2012 For week-1 (left panel), there is an increased chance for rainfall to exceed 50 mm over eastern Angola, portions of central and southern DRC, northern Zambia, southern Tanzania, Malawi, northern Mozambique and Madagascar. The probabilities of exceedence tend to decrease for week 2 (right panel) over many of these areas.

11. Experimental Week-1 Precipitation Outlooks Week-1 Outlook 04 – 10 January 2012 • There is an increased chance for above average rainfall over Malawi, northern Mozambique, and northwestern Madagascar: Anomalous cyclonic circulation, with its eastward propagation is expected to enhance rainfall in the region. Confidence: Moderate • There is an increased chance for below average rainfall over eastern Namibia, Botswana and portions of South Africa: Anomalous low-level divergent flow is expected to suppress rainfall in the region. Confidence: Moderate

12. Experimental Week-2 Precipitation Outlooks Week-2 Outlook 11 – 17 January 2012 • There is an increased chance for above average rainfall over eastern Madagascar: The eastward propagation of an anomalous cyclonic shear is expected to enhance rainfall in the region. Confidence: Moderate

13. Summary During the past seven days, below average rainfall was observed over Equatorial Guinea, much of Gabon, southern and central Congo, many parts of DRC, northern Angola, northeastern Zambia, Malawi, Burundi, portions of Uganda and Rwanda, southwestern Kenya, many parts of Tanzania, northern and southern Mozambique, local areas in northeastern South Africa and western Madagascar. In contrast, moisture surpluses were observed over local areas in northern DRC and eastern Tanzania, central and southern Angola, northeastern Namibia, local areas in Botswana and South Africa, many parts of Zimbabwe and Zambia, local areas in southern Mozambique and eastern Madagascar. During the past 30 days, southern Cameroon, Gabon, Equatorial Guinea, much of Congo, many parts of DRC, portions of northern and western Angola, eastern Zambia, Malawi, portions of South Africa, Swaziland, many parts of Mozambique and Madagascar, Kenya, Uganda, southern Somalia and southern Ethiopia received below average rainfall. In contrast, above average rainfall was observed over local areas in central Congo, portions of southern DRC, many parts of Angola, western Zambia, northern Namibia, Botswana, many parts of Zimbabwe and much of Tanzania. During the past 90 days, coastal Cote D’Ivoire, central Congo, local areas in CAR, western and southern DRC, Uganda, much of Tanzania, Kenya, southern Somalia, southern Ethiopia, western Zambia, portions of Angola, northern Botswana and local areas in eastern Zimbabwe received above average rainfall. Below average rainfall was observed across southern Cameroon, much of Gabon, Equatorial Guinea, local areas in DRC, portions of Mozambique, many parts of South Africa and Madagascar. Week-1 outlooks call for an increased chance for above average rainfall over southeastern Africa including Madagascar, while suppressed rainfall is expected across portions of southern Africa countries.