The African Monsoon Recent Evolution and Current Status

1. The African Monsoon Recent Evolution and Current Status Update prepared by Climate Prediction Center / NCEP 26 October 2009 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 rains persisted over Ethiopia and extended to other areas in the Greater Horn of Africa, where the rainfall season is off to a good start. • Heavy rains soaked parts of central Africa.

4. Rainfall Patterns: Last 7 Days During the past seven days moderate rains continued over portions of the Greater Horn of Africa, including parts of southern Ethiopia, southern Somalia, northern Kenya, central Sudan. Rain fall was above average over much of Nigeria, Benin and eastern parts of Cameroon, southern Chad and much of CAR. Rainfall was above average over much of DRC, western Angola and western Namibia. Rainfall was, however, below average over much of Uganda, Congo, southern Sudan, western Tanzania, Zambia, Zimbabwe and parts of South Africa Republic and Madagascar.

5. Rainfall Patterns: Last 30 Days During the past 30 days rainfall was above average over parts of the Sahel, and below average along the Guinean coast. Rainfall was also above average over much of Ethiopia and Somalia, parts of Kenya, parts of central Africa, including Cameroon , northern Congo, and southern DRC. Rainfall was below average over Gabon, southern Congo, parts of northern DRC, and CAR. Moisture surpluses were evident over portions of southern Africa, including central Angola, Botswana, and local areas in South Africa.

6. Recent Rainfall Evolution Daily evolution of precipitation during the last 90 days at selected regions shows that season-to-date totals are below average over the Gulf of Guinea region (lower panel – left). The rainfall season was off to a good start in the vicinity of the Lake Victoria. (lower panel – right). Persistent rains over the past several days erased long term rainfall deficits over western Ethiopia (upper panel – right).

7. Atmospheric Circulation:Last 7 Days The 850 hPa wind anomaly (left panel) reflected equatorial westerly wind anomalies over the central and eastern Atlantic, and easterly anomalies over the central Indian Ocean. The 200 hPa wind anomaly featured an anomalous upper level anticyclonic circulation off the coast of northwestern Africa and an anticyclonic circulation over southern Atlantic Ocean.

8. NCEP GEFS Model ForecastsNon-Bias Corrected Probability of precipitation exceedance Week-1: Valid 27 October – 02 November, 2009Week-2: Valid 03–09 November, 2009 For week-1 and week-2, the global ensemble forecast system (GEFS) suggests over a 90% chance for precipitation to exceed 25 mm along portions of the Guinean coast line, portions of central Africa, and parts of eastern Africa (week-1 only).

9. Experimental Week-1 Precipitation Outlooks Week-1 Outlook 27 October – 02 November, 2009 • There is an increased chance for above average precipitation over southern Nigeria, southern Cameroon, Gabon, Congo, western DRC and northwest Angola: The projected enhanced phase of the MJO over Africa and anomalous easterly winds converging into the western parts of the Equatorial Africa are expected to increase precipitation in the region. Confidence: Moderate • There is an increased chance for above average precipitation over southeastern Ethiopia, southern Somalia and eastern Kenya: The anomalous easterlies over western Indian Ocean and their associated convergence are expected to enhance precipitation in the region. Confidence: Moderate

10. Experimental Week-2 Precipitation Outlooks Week-2 Outlook 03 -09 November, 2009 • There is an increased chance for above average precipitation over western and central parts of Equatorial Africa, parts of CAB and the Horn of Africa region: The projected enhanced phase of the MJO over Africa isexpected to increase precipitation in the region. Confidence: Moderate

11. Summary • During the past seven days moderate rains continued over portions of the Greater Horn of Africa, including parts of southern Ethiopia, southern Somalia, northern Kenya, central Sudan. Rain fall was above average over much of Nigeria, Benin and eastern parts of Cameroon, southern Chad and much of CAR. Rainfall was above average over much of DRC, western Angola and western Namibia. Rainfall was, however, below average over much of Uganda, Congo, southern Sudan, western Tanzania, Zambia, Zimbabwe and parts of South Africa Republic and Madagascar. • During the past 30 days rainfall was above average over parts of the Sahel, and below average along the Guinean coast. Rainfall was also above average over much of Ethiopia and Somalia, parts of Kenya, parts of central Africa, including Cameroon , northern Congo, and southern DRC. Rainfall was below average over Gabon, southern Congo, parts of northern DRC, and CAR. Moisture surpluses were evident over portions of southern Africa, including central Angola, Botswana, and local areas in South Africa. • For week-1, the strengthening of the MJO is expected to increase precipitation along the east coast of the Gulf of Guinea, Congo, Gabon and parts of western DRC, northern Angola and along coastal East Africa. For week-2 the projected enhanced phase of the MJO is expected to increase precipitation in most areas over central Africa and parts of eastern Africa.