The African Monsoon Recent Evolution and Current Status Include Week-1 and Week-2 Outlooks Update prepared by Climate Prediction Center / NCEP 15 July 2013 For more information, visit:

Outline Highlights Recent Evolution and Current Conditions NCEP GEFS Forecasts Summary

Highlights: Last 7 Days Moderate to locally heavy rainfall resulted in moisture surpluses over southeastern Nigeria, southwestern Cameroon, and many parts of Ethiopia. Rainfall continued to be below-average over portions of Sudan and Eritrea, western South Sudan Republic and CAR. Week-1 outlooks call for an increased chance for above-average rainfall over portions of eastern Burkina Faso, southern Niger and northern Nigeria.

Rainfall Patterns: Last 7 Days During the past seven days, rainfall was below-average over western Guinea, local areas in Sierra Leone and Mali, portions of Burkina Faso, southern Togo, southern Benin, local areas in Nigeria, central Chad, much of CAR, portions of Sudan and Eritrea, western South Sudan, northern DRC, and local areas in Uganda. In Contrast, local areas in southern Mauritania, eastern Guinea, Liberia, parts of Cote d’Ivoire and Mali, western Burkina Faso, southwestern Ghana, local areas in Benin, southern Nigeria, Cameroon, local areas in southern Chad, eastern South Sudan, and many places in Ethiopia received above-average rainfall.

Rainfall Patterns: Last 30 Days During the past 30 days, below-average rainfall was observed over southern Senegal, Gambia, much of Liberia, Cote d’Ivoire, Ghana, local areas in Burkina Faso, much of Togo, southern Benin, local areas in Nigeria, northern Cameroon, Equatorial Guinea, parts of Gabon and Congo, local areas in DRC, the Lake Victoria region, southern and eastern Sudan, northwestern Ethiopia, and portions of Eritrea. In contrast, much of Guinea and Sierra Leone, portions of Mali, local areas in Burkina Faso, western Niger, southern Chad, portions of Cameroon, northern Congo, much of CAR, northern DRC, eastern South Sudan, and portions of Ethiopia had above-average rainfall.

Rainfall Patterns: Last 90 Days During the past 90 days, parts of Guinea Conakry, Sierra Leone, eastern Liberia, local areas in eastern Burkina Faso and Cote D’Ivoire, northern Benin, many parts of CAR, northern DRC, parts of South Sudan and western Ethiopia received above-average rainfall. In contrast, rainfall was below-average over many parts of Nigeria, local areas in Cameroon and Congo, eastern Sudan, northwestern Ethiopia, southwestern Kenya and eastern Uganda.

Rainfall Patterns: Last 180 Days During the past 180 days, rainfall was above-average over portions of Guinea, Sierra Leone, parts of Cote D’Ivoire, Togo, Benin, much of CAR, portions of DRC, local areas in South Sudan, parts of Ethiopia, western Kenya, southern Somalia, local areas in Tanzania, central and southern Mozambique, and local areas in Zimbabwe, Angola and Madagascar. In contrast, parts of Nigeria, eastern Gabon, local areas in DRC and Congo, eastern and southern Angola, many parts of Namibia and Botswana, southern Tanzania, northern Mozambique, and many parts of Madagascar had below-average rainfall.

Recent Rainfall Evolution Daily evolution of rainfall over the last 90 days at selected places reflects another week of suppressed rainfall over coastal Cote d’Ivoire (bottom panel-left). Moderate to heavy rains helped to erode some of the accumulated rainfall deficits over parts of Northwest Ethiopia (top panel-right). Moderate to heavy rains resulted in rainfall surpluses over parts of Cameroon (bottom panel-right.).

Atmospheric Circulation: Last 7 Days The 850hPa wind anomaly (left panel) featured anomalous dry northerly winds over Sudan and neighboring places, which may have contributed to the observed rainfall deficits in the region.

NCEP GEFS Model Forecasts Non-Bias Corrected Probability of precipitation exceedance Week-1: Valid July 16 – July 22, 2013 Week-2: Valid July 23 – July 29, 2013 For week-1 (left panel) there is an increased chance for rainfall to exceed 50 mm over parts Guinea, northern and southeastern Nigeria, parts of Cameroon, southern Chad, South Sudan and Ethiopia. For week-2 (right panel), higher probabilities of exceedance tend to increase southwestern West Africa.

Experimental Week-1 Precipitation Outlooks 1.There is an increased chance for above-average rainfall over northern Benin, portions of eastern Burkina Faso, southern Niger and northern Nigeria: Anomalous lower-level southwesterly flow, with its associated convergence is expected to enhance rainfall in the region. Confidence: Moderate July 16 – July 22, 2013

Experimental Week-2 Precipitation Outlooks July 23 – Jul 29, There is an increased chance for above-average rainfall over portions of Senegal, Gambia, Guinea-Bissau, Guinea, Sierra Leone, southern Mali, northwestern Cote d'Ivoire, Burkina Faso and portions of northern Ghana: Anomalous lower-level southwesterly winds, with their associated convergence are expected to enhance rainfall in the region.. Confidence: Moderate

Summary During the past seven days, rainfall was below-average over western Guinea, local areas in Sierra Leone and Mali, portions of Burkina Faso, southern Togo, southern Benin, local areas in Nigeria, central Chad, much of CAR, portions of Sudan and Eritrea, western South Sudan, northern DRC, and local areas in Uganda. In Contrast, local areas in southern Mauritania, eastern Guinea, Liberia, parts of Cote d’Ivoire and Mali, western Burkina Faso, southwestern Ghana, local areas in Benin, southern Nigeria, Cameroon, local areas in southern Chad, eastern South Sudan, and many places in Ethiopia received above-average rainfall. During the past 30 days, below-average rainfall was observed over southern Senegal, Gambia, much of Liberia, Cote d’Ivoire, Ghana, local areas in Burkina Faso, much of Togo, southern Benin, local areas in Nigeria, northern Cameroon, Equatorial Guinea, parts of Gabon and Congo, local areas in DRC, the Lake Victoria region, southern and eastern Sudan, northwestern Ethiopia, and portions of Eritrea. In contrast, much of Guinea and Sierra Leone, portions of Mali, local areas in Burkina Faso, western Niger, southern Chad, portions of Cameroon, northern Congo, much of CAR, northern DRC, eastern South Sudan, and portions of Ethiopia had above-average rainfall. During the past 90 days, parts of Guinea Conakry, Sierra Leone, eastern Liberia, local areas in eastern Burkina Faso and Cote D’Ivoire, northern Benin, many parts of CAR, northern DRC, parts of South Sudan and western Ethiopia received above-average rainfall. In contrast, rainfall was below-average over many parts of Nigeria, local areas in Cameroon and Congo, eastern Sudan, northwestern Ethiopia, southwestern Kenya and eastern Uganda. Week-1 outlooks call for an increased chance for above-average rainfall over portions of eastern Burkina Faso, southern Niger and northern Nigeria.