African Monsoon Recent Evolution & Outlooks Update

The African Monsoon Recent Evolution and Current Status Include Week-1 and Week-2 Outlooks Update prepared 21 April 2025 For more information, visit: http://www.cpc.ncep.noaa.gov/products/Global_Monsoons/African_Monsoons/precip_monitoring.shtml

Outline Highlights Recent Evolution and Current Conditions NCEP GEFS Forecasts Summary

Highlights: Last 7 Days During the past 7 days in West Africa, above-average rainfall was observed over central and eastern Guinea, eastern Sierra Leone, northern Liberia, southern and northern C te d Ivoire, southern parts of Mali and Burkina Faso, parts of western Ghana, central parts of Togo and Benin, and southwestern Nigeria. In contrast, below- average rainfall was recorded along the coastal areas of Ghana and many parts of southern and eastern Nigeria. In Central Africa, above-average rainfall was observed in parts of central CAR, northern Congo, and most parts of DRC. Meanwhile, below-average rainfall was recorded in many parts of Cameroon, Equatorial Guinea, Gabon, southern Congo, and over the far western and northeastern DRC. In Eastern Africa, above-average rainfall was observed in southeastern South Sudan, southern, southeastern and isolated areas in central and northern Ethiopia, most of Kenya, northeastern Uganda, parts of central Somalia, and the far northwestern and southeastern Tanzania. In contrast, below-average rainfall was noted in most of South Sudan, isolated areas in southwestern Ethiopia, southeastern Uganda, southeastern Kenya, southern Somalia, and southeastern Tanzania. In Southern Africa, above-average rainfall was observed in northwestern Angola, northern Zambia, most of Mozambique, central Zimbabwe, western Botswana and isolated areas in eastern Namibia, Lesotho, southeastern South Africa, and central Madagascar. Rainfall deficits are indicated in northwestern Angola and central Namibia. Week 1 forecasts indicate an increased chance of above-normal rainfall over the far southeastern Guinea, western and southern Cameroon, northern Gabon, isolated areas in central and eastern CAR, isolated areas in northwestern, central and southern DRC, northern and eastern Angola, western and northern Zambia, western and southeastern Tanzania, eastern Kenya, isolated areas in northern Mozambique, Lesotho and eastern South Africa, and over isolated areas in central Madagascar. In contrast, there is an increased chance of below-normal rainfall over the far southeastern areas of C te d Ivoire, southern areas of Ghana, Togo and Benin, central Nigeria, central Cameroon, coastal areas of Gabon, Congo and DRC, most of Uganda, southern, southeastern and isolated northeastern areas of Ethiopia, central and northern Somalia, and isolated areas in central Tanzania. Week 2 forecasts indicate an increased chance of above-normal rainfall in southern parts of the Gulf of Guinea extending from Liberia to Cameroon, over central CAR, northern, central and southern DRC, most of Angola, northern parts of Zambia, southern Tanzania and northern Mozambique, isolated areas in western Ethiopia, and isolated areas in central Madagascar. On the other hand, there is an increased chance of below-normal rainfall over Rwanda, Burundi and bordering areas of DRC, most of Uganda, northern Tanzania, western Kenya, southern and southeastern Ethiopia, and most of Somalia.

Rainfall Patterns: Last 90 Days In West Africa, above-average rainfall was observed in central and eastern Guinea, eastern Sierra Leone, Liberia, C te d'Ivoire, southern Mali, southwestern Burkina Faso, Ghana, Togo, Benin, and parts of southwestern Nigeria. In contrast, below-average rainfall was recorded in parts of eastern Nigeria. In Central Africa, below-average rainfall was observed over much of Cameroon, the Central African Republic (CAR), the far northern Congo, much of Gabon, and the northeastern parts of the Democratic Republic of Congo (DRC). In contrast, above-average rainfall was recorded in southern and central Congo and most of the DRC. In Eastern Africa, below-average rainfall was noted in the western and southern parts of South Sudan, parts of northeastern Ethiopia, western Uganda, and northwestern and coastal Tanzania. In contrast, parts of central and eastern South Sudan, southern and southwestern Ethiopia, eastern Uganda, much of Kenya, southern Somalia, and many parts of Tanzania received above-average rainfall. In Southern Africa, moisture deficits were observed over parts of western Angola, many areas of Zambia, western and northern borders of Zimbabwe, far eastern Botswana, Eswatini and northeastern South Africa, pockets of southern Mozambique, and northern Madagascar. In contrast, 90-day total rainfall remained above-average in many parts of Angola, much of Namibia, much of Botswana, central and eastern Zimbabwe, much of Mozambique, Malawi, many parts of South Africa, Lesotho, and central and southern Madagascar.

Rainfall Patterns: Last 30 Days Over the past 30 days in West Africa, above-average rainfall was observed across much of the Gulf of Guinea region, while parts of eastern Nigeria received below-average rainfall. In Central Africa, rainfall was below-average over much of Cameroon, the far eastern parts of the Central African Republic (CAR), most of Gabon excluding the western regions, northern and coastal Congo, and parts of coastal, northern, and northeastern Democratic Republic of the Congo (DRC). In contrast, above-average rainfall was observed in Equatorial Guinea, western Gabon, central Congo, and many parts of the DRC. In Eastern Africa, rainfall was below-average in parts of eastern/northeastern Ethiopia, western Uganda, Rwanda, parts of Burundi, and central and eastern Tanzania. Conversely, many parts of South Sudan, eastern Uganda, western and southern Ethiopia, central and southern Somalia, Kenya, and most parts of Tanzania received above-average rainfall. In Southern Africa, moisture deficits prevailed in the far western Angola, western and central Zambia, northern Zimbabwe, over isolated areas scattered across southern and northern Mozambique, northeastern South Africa, and western and northern parts of Madagascar. In contrast, 30-day total rainfall was above-average over much of Angola, Namibia, western and southern Botswana, many parts of South Africa, Lesotho, northern Zambia, northern and far southern Malawi, and pockets of Madagascar.

Rainfall Patterns: Last 7 Days During the past 7 days in West Africa, above-average rainfall was observed over central and eastern Guinea, eastern Sierra Leone, northern Liberia, southern and northern C te d Ivoire, southern parts of Mali and Burkina Faso, parts of western Ghana, central parts of Togo and Benin, and southwestern Nigeria. In contrast, below-average rainfall was recorded along the coastal areas of Ghana and many parts of southern and eastern Nigeria. In Central Africa, above-average rainfall was observed in parts of central CAR, northern Congo, and most parts of DRC. Meanwhile, below-average rainfall was recorded in many parts of Cameroon, Equatorial Guinea, Gabon, southern Congo, and over the far western and northeastern DRC. In Eastern Africa, above-average rainfall was observed in southeastern South Sudan, southern, southeastern and isolated areas in central and northern Ethiopia, most of Kenya, northeastern Uganda, parts of central Somalia, and the far northwestern and southeastern Tanzania. In contrast, below-average rainfall was noted in most of South Sudan, isolated areas in southwestern Ethiopia, southeastern Uganda, southeastern Kenya, southern Somalia, and southeastern Tanzania. In Southern Africa, above- average rainfall was observed in northwestern Angola, northern Zambia, most of Mozambique, central Zimbabwe, western Botswana and isolated areas in eastern Namibia, Lesotho, southeastern South Africa, and central Madagascar. northwestern Angola and central Namibia. Rainfall deficits are indicated in

Atmospheric Circulation: Last 7 Days Enhanced lower-level anomalous inland flow and supporting upper-level divergence contributed to the observed rainfall surplus in Mozambique. Southeasterly lower-level flow into Kenya and southerly to southeasterly moist flow into southern Ethiopia contributed to the observed rainfall surpluses in parts of eastern Africa.

NCEP GEFS Model Forecasts Non-Bias Corrected Probability of precipitation exceedance Week-1, Valid: 22 - 28 April 2025 Week-2, Valid: 29 April 05 May 2025 For Week-1 (left panel), GEFS forecasts indicate a high likelihood (over 70%) of rainfall exceeding 50 mm western Cameroon, Equatorial Guinea, northern Gabon, northeastern Angola and bordering areas of the DRC, northeastern DRC, Rwanda and Burundi, northwestern and northeastern Tanzania, southern Kenya, Lesotho, northeastern South Africa, and central Madagascar. Week-2 forecasts (right panel) indicate high exceedance probabilities in Liberia, southern Cameroon, Equatorial Guinea, Gabon, northern Angola, parts of Tanzania, and isolated places in southwestern Ethiopia.

Rainfall Evolution The daily evolution of rainfall over the past 90 days at selected locations shows that recent moderate to heavy rains have sustained moisture surpluses in parts of C te d'Ivoire (bottom left). In contrast, although a mild increase in precipitation slightly reduced the deficits, seasonal total rainfall remained below average in parts of Cameroon (bottom right) and northern Madagascar (top right).

Week-1 Precipitation Outlook 22 - 28 April 2025 1. The probabilistic forecasts predict a greater than 50% chance of weekly rainfall being below normal (below the lower tercile) across southern C te d Ivoire, southern Ghana, southern eastern Benin, western Nigeria, far northern Congo, southwestern Central African northeastern Democratic Republic of the Congo (DRC), southern South Sudan, central and northern Uganda, northeastern, Ethiopia, central and southeastern Mozambique. There is a greater than 80% chance of below-normal rainfall over parts of central Somalia. Togo, southern and Republic (CAR), central, northern and Somalia, southern and 2. The forecasts also indicate a greater than 50% chance of above-normal weekly total rainfall (above the upper tercile) over northern and central CAR, central and northern southwestern DRC, and including Lesotho, eastern Kenya, eastern Tanzania, and northern Mozambique. Additionally, there is a greater than 65% chance of above-normal rainfall over central and northern Angola, southwestern DRC, parts of South Africa, Lesotho, southeastern Kenya, eastern Tanzania, and northern Mozambique. Angola, parts central South and of Africa,

Week-2 Precipitation Outlook 29 April 05 May, 2025 1. The forecasts also indicate a greater than 50% chance of weekly total rainfall being above normal (above the upper tercile) over eastern Liberia, C te d Ivoire, southern Burkina Faso, Ghana, Togo, Benin, southern Nigeria, southern Gabon, southern Congo, southwestern Democratic Republic of the Congo (DRC), northern Central African Republic (CAR), southwestern Sudan, and parts of western, central, and southern Ethiopia, northeastern Mozambique, eastern South Lesotho, and northern Mozambique. There is a greater than 65% chance of above-normal rainfall over southern Gabon, southern Congo, southwestern DRC, southeastern Tanzania, Mozambique. southeastern Tanzania, Africa, and northeastern 2. The forecasts predict a greater than 50% chance of weekly rainfall being below normal (below the lower tercile) in parts of southeastern eastern Uganda, western Kenya, and parts of central and southern Somalia, with a greater than 65% chance of below-normal rainfall over parts of central Somalia. South Sudan,

Summary Over the past 30 days in West Africa, above-average rainfall was observed across much of the Gulf of Guinea region, while parts of eastern Nigeria received below-average rainfall. In Central Africa, rainfall was below-average over much of Cameroon, the far eastern parts of the Central African Republic (CAR), most of Gabon excluding the western regions, northern and coastal Congo, and parts of coastal, northern, and northeastern Democratic Republic of the Congo (DRC). In contrast, above-average rainfall was observed in Equatorial Guinea, western Gabon, central Congo, and many parts of the DRC. In Eastern Africa, rainfall was below-average in parts of eastern/northeastern Ethiopia, western Uganda, Rwanda, parts of Burundi, and central and eastern Tanzania. Conversely, many parts of South Sudan, eastern Uganda, western and southern Ethiopia, central and southern Somalia, Kenya, and most parts of Tanzania received above-average rainfall. In Southern Africa, moisture deficits prevailed in the far western Angola, western and central Zambia, northern Zimbabwe, over isolated areas scattered across southern and northern Mozambique, northeastern South Africa, and western and northern parts of Madagascar. In contrast, 30-day total rainfall was above-average over much of Angola, Namibia, western and southern Botswana, many parts of South Africa, Lesotho, northern Zambia, northern and far southern Malawi, and pockets of Madagascar. During the past 7 days in West Africa, above-average rainfall was observed over central and eastern Guinea, eastern Sierra Leone, northern Liberia, southern and northern C te d Ivoire, southern parts of Mali and Burkina Faso, parts of western Ghana, central parts of Togo and Benin, and southwestern Nigeria. In contrast, below-average rainfall was recorded along the coastal areas of Ghana and many parts of southern and eastern Nigeria. In Central Africa, above-average rainfall was observed in parts of central CAR, northern Congo, and most parts of DRC. Meanwhile, below-average rainfall was recorded in many parts of Cameroon, Equatorial Guinea, Gabon, southern Congo, and over the far western and northeastern DRC. In Eastern Africa, above-average rainfall was observed in southeastern South Sudan, southern, southeastern and isolated areas in central and northern Ethiopia, most of Kenya, northeastern Uganda, parts of central Somalia, and the far northwestern and southeastern Tanzania. In contrast, below-average rainfall was noted in most of South Sudan, isolated areas in southwestern Ethiopia, southeastern Uganda, southeastern Kenya, southern Somalia, and southeastern Tanzania. In Southern Africa, above-average rainfall was observed in northwestern Angola, northern Zambia, most of Mozambique, central Zimbabwe, western Botswana and isolated areas in eastern Namibia, Lesotho, southeastern South Africa, and central Madagascar. Rainfall deficits are indicated in northwestern Angola and central Namibia. Week 1 forecasts indicate an increased chance of above-normal rainfall over the far southeastern Guinea, western and southern Cameroon, northern Gabon, isolated areas in central and eastern CAR, isolated areas in northwestern, central and southern DRC, northern and eastern Angola, western and northern Zambia, western and southeastern Tanzania, eastern Kenya, isolated areas in northern Mozambique, Lesotho and eastern South Africa, and over isolated areas in central Madagascar. In contrast, there is an increased chance of below-normal rainfall over the far southeastern areas of C te d Ivoire, southern areas of Ghana, Togo and Benin, central Nigeria, central Cameroon, coastal areas of Gabon, Congo and DRC, most of Uganda, southern, southeastern and isolated northeastern areas of Ethiopia, central and northern Somalia, and isolated areas in central Tanzania. Week 2 forecasts indicate an increased chance of above-normal rainfall in southern parts of the Gulf of Guinea extending from Liberia to Cameroon, over central CAR, northern, central and southern DRC, most of Angola, northern parts of Zambia, southern Tanzania and northern Mozambique, isolated areas in western Ethiopia, and isolated areas in central Madagascar. On the other hand, there is an increased chance of below-normal rainfall over Rwanda, Burundi and bordering areas of DRC, most of Uganda, northern Tanzania, western Kenya, southern and southeastern Ethiopia, and most of Somalia.