African Monsoon Recent Evolution Update

The African Monsoon Recent Evolution and Current Status Include Week-1 and Week-2 Outlooks Update prepared 28 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, southern and eastern Guinea, Sierra Leone, Liberia, C te d Ivoire, southern Mali, western Burkina Faso, many parts of Ghana and Togo, central, eastern and southern Benin, and parts of southwestern and southern Nigeria. In contrast, below-average rainfall was recorded in central, eastern and parts of northwestern Nigeria and central-eastern Burkina Faso. In Central Africa, above-average rainfall was observed in parts of central- southern Central African Republic (CAR), eastern Congo, western Gabon, and parts of northwestern, western, southwestern, southern, central and southeastern Democratic Republic of Congo (DRC). Meanwhile, below-average rainfall was recorded in many parts of Cameroon and Equatorial Guinea, parts of northern, central and eastern Gabon, western Congo, western and southeastern CAR, and northeastern DRC. In Eastern Africa, above-average rainfall was observed in southern, southwestern and isolated areas in central and northern Ethiopia, most of Kenya, some parts of southern Sudan, central and northeastern South Sudan and western Burundi, eastern Uganda, central Eritrea, southern Somalia, and southern, southwestern and northern Tanzania. In contrast, below-average rainfall was noted in western and southwestern South Sudan, northwestern, central, southern and parts of western Uganda, eastern Rwanda, parts of central and eastern Ethiopia, Djibouti, northwestern and central Somalia, and parts of central and northwestern Tanzania. In Southern Africa, above-average rainfall was observed in northern, central, eastern and southern Angola, northern, central, eastern and southeastern Namibia, northern, western, central and southern Botswana, northern Zambia, parts of central and eastern Zimbabwe, northern, eastern and southern Malawi, northern, central, western and eastern Mozambique, western, central, southern and eastern South Africa, Lesotho, southern Eswatini, and central and southern Madagascar. Rainfall deficits are indicated in western Angola, central and southern Zambia, northern Zimbabwe, and some parts of northern South Africa, northern Eswatini and southern Mozambique, and northern and western Madagascar. The Week-1 outlook calls for above-average rainfall in southern Guinea, Sierra Leone, Liberia, C te d Ivoire, Ghana, southern Cameroon, much of western, southwestern and central DRC, northern Angola, southern Tanzania, northern and eastern Mozambique, central-eastern South Africa, Eswatini, and some parts of eastern Madagascar. In contrast, there is an increased chance for below- average in some parts of southern Chad, central-eastern Somalia, and eastern and southeastern Uganda. The Week-2 outlook calls for above-average rainfall in Gabon, western, central and southern Congo, northern Angola, western, central- eastern and northern DRC, and some parts of southwestern South Sudan and western Ethiopia. In contrast, there is an increased chance for below-average in parts of central and eastern Nigeria, northern Cameroon, and some parts of southern Ethiopia, southwestern Kenya and central Somalia.

Rainfall Patterns: Last 90 Days Over the past 90 days, In West Africa, above-average rainfall was observed in central, northern, southern and eastern Guinea, Sierra Leone, Liberia, C te d Ivoire, southern Mali, western Burkina Faso, many parts of Ghana and Togo, central, southern and eastern Benin, and southwestern and southern Nigeria. In contrast, below-average rainfall was recorded in central, eastern and parts of northwestern Nigeria and central-eastern Burkina Faso. In Central Africa, above-average rainfall was observed in some parts of central and southern Central African Republic (CAR), eastern and southeastern Congo, western Gabon, and parts of northwestern, western, southwestern, southern-central, and southeastern Democratic Republic of Congo (DRC). Meanwhile, below-average rainfall was recorded in many parts of Cameroon and Equatorial Guinea, parts of northern, central and eastern Gabon, western and northwestern Congo, western and southeastern CAR, and northeastern DRC. In Eastern Africa, above-average rainfall was observed in parts of southern, western, southwestern and some parts of central Ethiopia, central Eritrea, southern Somali, Kenya, some parts of southern Sudan, central and northeastern South Sudan, eastern Uganda, western Burundi, and parts of northern, western, southwestern and southern Tanzania. In contrast, below-average rainfall was noted in southern parts of South Sudan, northern, central-eastern and southern Uganda, eastern and parts of central and southeastern Ethiopia, Djibouti, central and northwestern Somalia, and some parts of central Tanzania. In Southern Africa, above-average rainfall was observed in northern, central, eastern and southern Angola, northern, central, eastern and southeastern Namibia, northern, western, central and southern Botswana, northern Zambia, eastern and southern Malawi, northern, western, central and eastern Mozambique, some parts of central and eastern Zimbabwe, western, central, eastern and parts of southern South Africa, Lesotho, and central and southeastern Madagascar. In contrast, below-average rainfall was observed in some parts of western Angola, central and southern Zambia, northern and western Zimbabwe, and some parts of southern Mozambique, northern South Africa, northern Eswatini, and northern and northwestern Madagascar.

Rainfall Patterns: Last 30 Days Over the past 30 days, In West Africa, above-average rainfall was observed in central, northern, southern and eastern Guinea, Sierra Leone, Liberia, C te d Ivoire, southern Mali, western Burkina Faso, parts of western, southern and southeastern Ghana, Togo, many parts of Benin, and southwestern and southern Nigeria. In contrast, below-average rainfall was recorded in central, eastern and parts of northwestern Nigeria and central-eastern Burkina Faso. In Central Africa, above- average rainfall was observed in parts of western, central, southern and northern Central African Republic (CAR), northeastern and southeastern Congo, western Gabon, and parts of northwestern, western, southwestern, southern, and southeastern Democratic Republic of Congo (DRC). Meanwhile, below-average rainfall was recorded in many parts of Cameroon and Equatorial Guinea, parts of northern, central and eastern Gabon, western and southwestern Congo, pockets of region in southeastern CAR, and parts of central and northeastern DRC. In Eastern Africa, above-average rainfall was observed in parts of western, southwestern and southern Ethiopia, central Eritrea, most of Kenya, central, eastern and northwestern South Sudan, some parts of southern Sudan and southern Somalia, many parts of Rwanda and Burundi, and parts of northern, western, southwestern and southern Tanzania. In contrast, below-average rainfall was noted in southern parts of South Sudan, northern, central-eastern and southern Uganda, eastern and parts of central and southeastern Ethiopia, southern Eritrea, Djibouti, central Somalia, and some parts of central-southern Tanzania. In Southern Africa, above-average rainfall was observed in northern, central, eastern and southern Angola, northern, central-eastern and southeastern Namibia, many parts of Botswana, western, northern and eastern Zambia, western and eastern Zimbabwe, eastern and southern Malawi, parts of northern, western, central and eastern Mozambique, western, central, eastern and parts of southern South Africa, Lesotho, Eswatini, and central and southeastern Madagascar. In contrast, below-average rainfall was observed in some parts of northwestern and southwestern Angola, western-central Namibia, central Zambia, western Zimbabwe, and northern and southwestern Madagascar.

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

Atmospheric Circulation: Last 7 Days At 700-hPa level (left panel), lower-level anomalous cyclonic circulation was observed in parts of South Africa which may have contributed to the observed rainfall increases across many parts of central and eastern South Africa.

NCEP GEFS Model Forecasts Non-Bias Corrected Probability of precipitation exceedance Week-1, Valid: 29 April 05 May, 2025 Week-2, Valid: 06 12May, 2025 For week-1 (left panel) the NCEP GEFS indicates a moderate to high chance (over 70%) for rainfall to exceed 50 mm in parts of central and eastern Liberia, parts of southwestern and southern Cameron, Equatorial Guinea, southeastern Congo, eastern DRC, many parts of Rwanda and Burundi, parts of northern and western Angola, southern Ethiopia, eastern Tanzania, and some coastal regions in eastern Madagascar. For week-2 (right panel), NCEP GEFS indicates a moderate to high chance (over 70%) for rainfall to exceed 50 mm in southwestern and southern Cameroon, Equatorial Guinea, many parts of Gabon, southwestern Congo, eastern DRC, many parts of Rwanda and Burundi, and some coastal regions in eastern Tanzania.

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 29 April 05 May, 2025 1. The probabilistic forecasts indicate a greater than 50% chance of above-normal weekly total rainfall (above the upper tercile) over much of Liberia, eastern Guinea, most of southern Cameroon, eastern Gabon, the Republic of the Congo, western and central DRC, northern Angola, southern Tanzania, southern Mozambique, eastern South Africa, and northeastern Madagascar. Additionally, there is a greater than 80% chance of above-normal rainfall over parts of southwestern Tanzania. C te d Ivoire, Ghana, northern and far DRC and eastern 2. The forecasts also predict a greater than 50% chance of below-normal weekly rainfall (below the lower tercile) over southern and eastern Uganda, western Kenya, and central Somalia, with a greater than 65% chance of below-normal rainfall over central Somalia.

Week-2 Precipitation Outlook 06 12 May, 2025 1. The probabilistic forecasts predict a greater than 50% chance of below-normal weekly rainfall (below the lower tercile) in parts of northeastern Cameroon, and central Somalia. Nigeria, northern 2. The forecasts also indicate a greater than 50% chance of above-normal weekly total rainfall (above the upper tercile) over much of Equatorial Guinea, Gabon, the Republic of the Congo, the Democratic Republic of the Congo (DRC), southwestern South Sudan, far western Ethiopia, southeastern Tanzania, Madagascar. There is also a greater than 80% chance of above-normal rainfall over southwestern DRC. and far northern southern Congo and

Summary Over the past 30 days, In West Africa, above-average rainfall was observed in central, northern, southern and eastern Guinea, Sierra Leone, Liberia, C te d Ivoire, southern Mali, western Burkina Faso, parts of western, southern and southeastern Ghana, Togo, many parts of Benin, and southwestern and southern Nigeria. In contrast, below-average rainfall was recorded in central, eastern and parts of northwestern Nigeria and central-eastern Burkina Faso. In Central Africa, above-average rainfall was observed in parts of western, central, southern and northern Central African Republic (CAR), northeastern and southeastern Congo, western Gabon, and parts of northwestern, western, southwestern, southern, and southeastern Democratic Republic of Congo (DRC). Meanwhile, below-average rainfall was recorded in many parts of Cameroon and Equatorial Guinea, parts of northern, central and eastern Gabon, western and southwestern Congo, pockets of region in southeastern CAR, and parts of central and northeastern DRC. In Eastern Africa, above-average rainfall was observed in parts of western, southwestern and southern Ethiopia, central Eritrea, most of Kenya, central, eastern and northwestern South Sudan, some parts of southern Sudan and southern Somalia, many parts of Rwanda and Burundi, and parts of northern, western, southwestern and southern Tanzania. In contrast, below-average rainfall was noted in southern parts of South Sudan, northern, central-eastern and southern Uganda, eastern and parts of central and southeastern Ethiopia, southern Eritrea, Djibouti, central Somalia, and some parts of central-southern Tanzania. In Southern Africa, above-average rainfall was observed in northern, central, eastern and southern Angola, northern, central-eastern and southeastern Namibia, many parts of Botswana, western, northern and eastern Zambia, western and eastern Zimbabwe, eastern and southern Malawi, parts of northern, western, central and eastern Mozambique, western, central, eastern and parts of southern South Africa, Lesotho, Eswatini, and central and southeastern Madagascar. In contrast, below-average rainfall was observed in some parts of northwestern and southwestern Angola, western-central Namibia, central Zambia, western Zimbabwe, and northern and southwestern Madagascar. During the past 7 days in West Africa, above-average rainfall was observed over central, southern and eastern Guinea, Sierra Leone, Liberia, C te d Ivoire, southern Mali, western Burkina Faso, many parts of Ghana and Togo, central, eastern and southern Benin, and parts of southwestern and southern Nigeria. In contrast, below-average rainfall was recorded in central, eastern and parts of northwestern Nigeria and central-eastern Burkina Faso. In Central Africa, above-average rainfall was observed in parts of central-southern Central African Republic (CAR), eastern Congo, western Gabon, and parts of northwestern, western, southwestern, southern, central and southeastern Democratic Republic of Congo (DRC). Meanwhile, below-average rainfall was recorded in many parts of Cameroon and Equatorial Guinea, parts of northern, central and eastern Gabon, western Congo, western and southeastern CAR, and northeastern DRC. In Eastern Africa, above-average rainfall was observed in southern, southwestern and isolated areas in central and northern Ethiopia, most of Kenya, some parts of southern Sudan, central and northeastern South Sudan and western Burundi, eastern Uganda, central Eritrea, southern Somalia, and southern, southwestern and northern Tanzania. In contrast, below-average rainfall was noted in western and southwestern South Sudan, northwestern, central, southern and parts of western Uganda, eastern Rwanda, parts of central and eastern Ethiopia, Djibouti, northwestern and central Somalia, and parts of central and northwestern Tanzania. In Southern Africa, above-average rainfall was observed in northern, central, eastern and southern Angola, northern, central, eastern and southeastern Namibia, northern, western, central and southern Botswana, northern Zambia, parts of central and eastern Zimbabwe, northern, eastern and southern Malawi, northern, central, western and eastern Mozambique, western, central, southern and eastern South Africa, Lesotho, southern Eswatini, and central and southern Madagascar. Rainfall deficits are indicated in western Angola, central and southern Zambia, northern Zimbabwe, and some parts of northern South Africa, northern Eswatini and southern Mozambique, and northern and western Madagascar. The Week-1 outlook calls for above-average rainfall in southern Guinea, Sierra Leone, Liberia, C te d Ivoire, Ghana, southern Cameroon, much of western, southwestern and central DRC, northern Angola, southern Tanzania, northern and eastern Mozambique, central-eastern South Africa, Eswatini, and some parts of eastern Madagascar. In contrast, there is an increased chance for below-average in some parts of southern Chad, central-eastern Somalia, and eastern and southeastern Uganda. The Week-2 outlook calls for above-average rainfall in Gabon, western, central and southern Congo, northern Angola, western, central-eastern and northern DRC, and some parts of southwestern South Sudan and western Ethiopia. In contrast, there is an increased chance for below-average in parts of central and eastern Nigeria, northern Cameroon, and some parts of southern Ethiopia, southwestern Kenya and central Somalia.