Increasing flood risk with forecasted above-average rains in parts of the northern sector

• The onset of the June to September rains has been mixed over the northern unimodal sector of the region. Across northern South Sudan, northwestern Ethiopia, and parts of south-central Sudan, rains were delayed by up to 10 to 20 days, while parts of southeastern South Sudan, southwestern Ethiopia, and much of Sudan saw a timely to early start to the rains. 
• Given ongoing and forecasted above-average seasonal rains, combined with high river levels and flows, there is an elevated risk of flooding at the peak of the seasonal rains in the northern sector of the region. In South Sudan and Sudan, this is likely to be worsened by the release of a high volume of water from the Jinja Dam in Uganda into the Nile basin starting in May due to record high water levels in Lake Victoria and the Nile River basin.
• Mixed crop production prospects are expected across most bimodal regions of South Sudan, Uganda, Kenya, Somalia, and in the belg cropping regions of Ethiopia following the slow rainfall onset and mixed cumulative rainfall. 
• Concern remains over the expected below-average production in the eastern sector of the region, including southeast Kenya and coastal and southern regions of Somalia, despite the largely above-average March to May rainfall.
• Current exceptional vegetation conditions and surface water pans levels in pastoral areas of northern Kenya, most parts of Somalia, and Somali Region of Ethiopia were supported by the extremely above-average mid-April to May rainfall.

Context: Between June and September, the following are the areas and names of the rainy seasons underway in parts of East Africa: kiremt rains (June to September) in western and northern Ethiopia; main rainy season (June to September) in the  unimodal zones of South Sudan and Sudan; long rains in unimodal Uganda and Kenya; karan/karma rains (July to September) in northern pastoral areas of Ethiopia and Sitti and Fafan zones of Somalia; and second rains (July to November) in South Sudan bimodal zone.

Generally, the start of the June through September rainy season has been favorable for both crops and vegetation across the region. The season is currently underway in the northern sector of the region – covering western, northern, and central parts of Ethiopia and most of Sudan and South Sudan – and has thus far been characterized by mixed onset but average to above-average rainfall (Figure 1). In southeastern Sudan and northwestern Ethiopia, rainfall through June in some areas has been 200-300 percent above average (Figure 1). However, central Ethiopia has experienced a slower onset with parts of the region already reporting rainfall deficits. In areas of Ethiopia that benefit from the kiremt rainfall season, onset has been varied: the eastern areas have had a slow and below-average start, while the western areas have received a timely and above-average start. Farmers who have started planting are benefiting from these rains, especially given the favorable belg season in areas that overlap the two seasons, such as central Oromia. 

In June, the eastern regions of South Sudan have received largely average rainfall. This trend also spread across some bimodal areas, easing some of the earlier deficits from the March to May season, particularly in the greenbelt areas of southern South Sudan. The western parts of South Sudan have continued to experience localized rainfall deficits, leading to concern as the June to September season sets in.  

The March to May season for the bimodal regions was characterized by a delayed onset with below-average rainfall. As the season progressed, rainfall increased and eased some deficits. This benefited the pastoral sector (Figure 2) with exceptional vegetation conditions across the eastern sector of the regions including eastern to northeastern Kenya, and most parts of Somalia and Somali Region in Ethiopia. This has also improved the surface water pan levels leading to improved livestock body conditions across these regions. However, the benefits are likely to be short-lived given the sustained extreme temperatures across these regions. 

In terms of crop status, the bimodal regions are already at the reproductive stage with favorable conditions across most of the regions (Figure 3), especially in the central highlands and western Kenya; most of Uganda, bimodal South Sudan, and Rwanda, despite the early seasonal deficits; and Burundi and northern Tanzania, despite the early seasonal flooding incidents. In eastern, southeastern, and coastal Kenya and central Somalia, the season was short-lived despite the cumulatively above-average rainfall and dry spells are leading to depressed soil moisture at a critical cropping stage. The crops are at reproductive stage, but harvest is expected to be below average. 

For the unimodal March to May season, the crops are at late vegetative to reproductive stages and mostly favorable despite the early seasonal deficits. These regions include Karamoja in Uganda and the long rains season in the North Rift Valley areas in Kenya. The season continues through November in the Rift Valley region and the forecast indicates a slight decrease in rainfall within the coming month, so a close watch is needed. 

The July rainfall outlook, based on NMME one-month forecasts (Figure 5), indicates continued above-average rains over western Ethiopia, Sudan, South Sudan, Uganda, western and coastal Kenya, and coastal Somalia. 

Given expectations for La Niña-driven above-average rainfall over the northern sector, the risk of flooding is high for large parts of South Sudan, Sudan, and Ethiopia. In South Sudan and Sudan, this is exacerbated by the release of large volumes of water from the Jinja Dam earlier in May by the Uganda government, which is expected to contribute to severe flooding worse than that of 2020 and 2022. Flood risks also persist in parts of the Darfur Region, Kassala, and Blue Nile of Sudan.

Short-term forecasts (one to two weeks) indicate a likelihood of localized below-average rainfall across parts of western Kenya, eastern Ethiopia, and parts of Uganda, suggesting potential dry spells within the ongoing season.