The African Monsoon Recent Evolution and Current Status Update prepared by Climate Prediction Center / NCEP 09 November 2009 For more information, visit:

Outline Highlights Recent Evolution and Current Conditions NCEP GEFS Forecasts Summary

Highlights: Last 7 Days During the past seven days moderate rains continued over southern Somalia and southern Ethiopia while much of CAR had experienced moderate to heavy rainfall. Rainfall was below average over the rest of Greater Horn of Africa except for some local rainfall events. On the other hand, Coastal Gulf of Guinea had experienced near average to above average rainfall. Rainfall was near or above average over much of the DRC and northern Angola. Rainfall was below average over parts of Zimbabwe and Mozambique while parts of South Africa Republic and southeastern Madagascar had experienced above average rainfall.

Rainfall Patterns: Last 7 Days During the past seven days moderate rains continued over southern Somalia and southern Ethiopia while much of CAR had experienced moderate to heavy rainfall. Rainfall was below average over the rest of Greater Horn of Africa except for some local rainfall events. On the other hand, Coastal Gulf of Guinea had experienced near average to above average rainfall. Rainfall was near or above average over much of the DRC and northern Angola. Rainfall was below average over parts of Zimbabwe and Mozambique while parts of South Africa Republic and southeastern Madagascar had experienced above average rainfall.

Rainfall Patterns: Last 30 Days During the past 30 days rainfall was above average over parts of the Sahel and interior Gulf of Guinea while the rainfall was 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 northern Congo and much of the DRC. Rainfall was below average over southern Sudan, Uganda, western Tanzania, much of Zambia, Zimbabwe and Mozambique. Moisture surpluses were evident over much of Angola, northern Namibia, portions of southern Africa and Botswana.

Recent Rainfall Evolution Daily evolution of precipitation during the last 90 days at selected regions shows that season-to- date totals are above average over the Guinea highlands (lower panel –left) while the deficits continued along the coastal Gulf of Guinea region (lower panel – right). Heavy rains during later part of October over southern Somalia and eastern Kenya erased the deficits and caused flooding in some areas (upper panel – right).

Atmospheric Circulation: Last 7 Days The 850 hPa wind anomaly (left panel) reflected an anticyclonc circulation over the northern Atlantic a southerly flow over the Mozambique Channel. The 200hpa wind anomaly reflected southerly flow over west Africa and a northwesterly flow in the southern Atlantic extending into southern Africa.

NCEP GEFS Model Forecasts Non-Bias Corrected Probability of precipitation exceedance Week-1: Valid 10 – 16 November, 2009 Week-2: Valid 17–23 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 over parts of central Africa.

Experimental Week-1 Precipitation Outlooks Week-1 Outlook 10 – 16 November, There is an increased chance for above average precipitation over southern and eastern parts of DRC, Rwanda, Burundi, western Tanzania, northern parts of Zambia and eastern Angola: The anomalous westerly wind from southern Atlantic Ocean and it associated convergence over the CAB region and adjacent areas is expected to increase precipitation in the region. Confidence: Moderate

Experimental Week-2 Precipitation Outlooks Week-2 Outlook November, No Forecast: Weak signal. Confidence: Moderate

Summary During the past seven days moderate rains continued over southern Somalia and southern Ethiopia while much of CAR had experienced moderate to heavy rainfall. Rainfall was below average over the rest of Greater Horn of Africa except for some local rainfall events. On the other hand, Coastal Gulf of Guinea had experienced near average to above average rainfall. Rainfall was near or above average over much of the DRC and northern Angola. Rainfall was below average over parts of Zimbabwe and Mozambique while parts of South Africa Republic and southeastern Madagascar had experienced above average rainfall. During the past 30 days rainfall was above average over parts of the Sahel and interior Gulf of Guinea while the rainfall was 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 northern Congo and much of the DRC. Rainfall was below average over southern Sudan, Uganda, western Tanzania, much of Zambia, Zimbabwe and Mozambique. Moisture surpluses were evident over much of Angola, northern Namibia, portions of southern Africa and Botswana. For week1, the anomalous westerly wind from southern Atlantic Ocean and it associated convergence over the CAB region and adjacent areas is expected to increase precipitation in the region. For week2, due to weak signal climatology is expected and hence no forecast is issued.