Earlier-than-normal to timely onset of long rains, Gu, and Belg seasons in most of East Africa

• Despite rainfall deficits in late March and early April, the onset of the March to May seasonal rains in most of bimodal areas of East Africa has been slightly early or on time. However, although the Belg rains in Ethiopia were timely in the southwest, they are slightly delayed in central and northeastern regions. Current and forecast rainfall is conducive for desert locust breeding and development.

• The western sector of the region experienced a dry spell resulting in early season rainfall deficits in late March and early April. However, cumulative rainfall since early March is above average in most areas. According to the forecast, current deficits are likely to be eliminated with the expected peak of the seasonal rains in April.

• Due to the above-average rainfall received in late 2019 and early 2020, rangeland resources remain significantly above average in many areas. However, recent drier conditions have led to negative vegetation anomalies in some localized areas.

• The rainfall outlook through April 16 indicates an increased likelihood of widespread moderate to locally very heavy rains across the region, with elevated risks of flash floods in flood prone areas.

The Belg rainfall season in southwestern Ethiopia has had a timely onset, while a slight delay is observed in central and northern Ethiopia. The long rains/Gu rainfall season in bimodal areas of the region has generally exhibited a slightly early or timely start, including in Kenya, Uganda, Somalia, Ethiopia, southeastern South Sudan, Burundi, and Rwanda. Cumulative rainfall performance since March 1^st is broadly above average in these areas, though a dry spell occurred in some areas during the late March and early April period (Figures 1 and 2). After heavy rainfall in early and mid-March, rainfall amounts were below average from March 26^th to April 5^th in Uganda, Rwanda, Burundi, southeastern South Sudan, parts of Belg-dependent Ethiopia, and Tanzania. Deficits of 10-100 mm are observed, with the most severe deficits observed in southern Tanzania. With the exception of localized riverine flooding in Kenya, the dryness served to temporarily alleviate previous concerns for elevated flood risk in late March/early April in much of the region.

According to the eMODIS/Normalized Difference Vegetation Index for April 1-10, recent seasonal dryness in parts of unimodal areas of Ethiopia and South Sudan and the recent rainfall deficits in parts of Belg-dependent Ethiopia and bimodal areas of Uganda, Tanzania, Rwanda, and Burundi have led to below-normal vegetation conditions (Figure 2). In contrast, above-normal vegetation conditions continue to persist in northern and central Somalia, parts of Ethiopia, much of northern and central Kenya, northeastern Uganda, and southeastern South Sudan, which is attributed to the lasting effects of prior October to December 2019 rainfall coupled with cumulative rainfall performance since early March. The favorable vegetation in these areas have attracted high concentrations of desert locust. According to satellite-derived data on surface water points, water resources broadly remain in good status across the region, though there are pockets of northwestern South Sudan, Sudan, and northwestern Somalia where water resources are beginning to dry up.

According to FAO Desert Locust Watch and field information, desert locust breeding and formation of new swarms is ongoing in northern and central Somalia, northern and central Kenya, southwestern Belg cropping areas of Ethiopia, and Yemen. In addition, mature swarms have arrived in southeastern bimodal cropping areas of South Sudan and are spreading in unimodal areas of Karamoja sub-region in Uganda. The start of the long rains/Gu season is sustaining conducive ecological conditions for egg-laying, which is expected to lead to the formation of new swarms by late June or July. Conversely, the progressively dry conditions in Sudan is leading to a decline in desert locust presence. Surveillance and control measures are ongoing in Ethiopia and Kenya, and to a lesser extent in Uganda and Yemen.

Current and forecast climatic conditions indicate that enhanced rainfall performance from mid-April through May/June should support favorable crop production and livestock production prospects. However, the forecast at the peak of the seasonal bimodal rains in April indicate an elevated risk of riverine and flash floods in several areas, contrasted with localized rainfall deficits. The following is a country-by-country update on recent seasonal progress to date:

• In Somalia, satellite data and field information continue to indicate favorable rangeland conditions in northern and central areas, which persisted throughout the January to March Jilaal dry season despite high temperatures and ongoing breeding of desert locusts in northern and central Somalia. This is attributed to the preceding October to December Deyr rains that extended into early January. Most pastoral communities have benefitted from above-normal pasture and water availability; however, part of northern Somalia began to report that water sources had begun to evaporate in March. The Gu season, which normally begins mid-April in southern regions and slowly spreads to the north, has begun 10-20 days early. As a result, cumulative rainfall anomalies of 10-50 mm are observed in southern Somalia from March 1^st to April 5^th. This has supported land preparation and sowing for the Gu agricultural season.
• In Ethiopia, Belg season rainfall has been timely across the southern and southwestern regions and parts of the Rift Valley. However, rainfall deficits in other parts of the Valley and in Tigray, Afar, and Oromia regions are indicative of a slight delay in the establishment of the rains in northern and northeastern Ethiopia. The below-average rainfall in these areas slightly delayed the start of the Belg season and planting for Belg crops. In April, Gu rainfall in southeastern pastoral areas is indicative of a timely onset. Desert Locust in Belg cropping areas presents an increasing threat to food security, with rising concern for the potential for swarms to migrate further into central and western Belg crop-producing areas. The rainfall forecast indicates that enhanced rainfall in the next 1 – 2 weeks is most likely to alleviate existing rainfall deficits. However, depressed rainfall is expected to persist in northern Afar and eastern Oromia.
• In Kenya, water and rangeland remains broadly favourable in most pastoral areas. The start of the February – September unimodal rainfall season and the March – May bimodal rainfall season have been timely, though some areas had a slightly early onset. Above-average rainfall has persisted since March in many areas, with excessive rainfall resulting in flooding in low-lying, flood-prone areas along western Kenya’s Nyando and Nzoia rivers. In contrast, areas near the Lake Victoria basin exhibit rainfall deficits of up to 50 mm since late March. Land preparation and planting for the long rains season is ongoing in western and central counties. Desert locust breeding and swarm formation are ongoing in northern and central counties, with hoppers recently reported in Marsabit county and its neighbors. A forecast of enhanced rainfall in the next 1 – 2 weeks is expected to elevate the flood risk in western Kenya, especially in low lying and riverine areas.
• In Sudan, conditions remain seasonally dry. Mixed to below-normal vegetation conditions are observed.
• In South Sudan, the bimodal rainfall season started on time in Eastern Equatoria, though slight deficits are indicative of a delay in the onset of rains in parts of Central and Western Equatoria states. Key informants report that farmers are preparing land for first-season planting. The rest of the country, which is dependent on unimodal rainfall, is seasonally dry. Vegetation conditions remain far above normal in most eastern regions and parts of the north, especially in the Nile Sobat and Kapoeta areas. However, pockets of depressed vegetation can be spotted in the southwest.
• In Uganda, the onset of the March – May seasonal rains was established in most parts of country in early March, which triggered crop planting. However, the unusual dry spell in early April has affected crop germination and performance. The Uganda National Meteorological Authority has issued an advisory that the seasonal rains are forecast to resume normally across the country in the coming weeks, with an increased likelihood for localized flash floods in flood prone, lowland and urban areas with poor drainage systems. Some desert locust swarms are reported in Karamoja of northeastern Uganda and pose a threat to the emergence of crops that are likely to reach their vegetative stages in April.

• In Rwanda and Burundi, the late March-early April period has been characterized by rainfall deficits despite the earlier establishment of the rainfall season. However, the preceding rainfall was favorable for crop production and forecasts indicate recovery. As a result, the current deficits are most likely to have little impact on crop production prospects. 

• In Tanzania, vegetation conditions vary from slightly below average to average in southern and central region. This may be due to localized waterlogging from cumulative above-average rainfall over past months or due to earlier-than-normal green harvesting for the Msimu season. The two-week rainfall deficits are likely to be eliminated in the next 1-2 weeks, and the flood risk is elevated in southern, central, and coastal regions.
• In Yemen, satellite-derived information indicates seasonally normal rainfall since early March. Vegetation conditions are above normal in the western coastal strip and range from near normal to slightly below normal elsewhere. Desert locust breeding has been reported along the Red Sea and Gulf of Aden coasts and in the interior near Marib and on the eastern plateau, according to FAO.

The rainfall forecast through April 16^th is indicative of enhanced rain in long rains and Belg rains in the western sector and parts of the Horn (Figure 3). The heaviest rainfall is expected in Tanzania, with possible storms in coastal Tanzania, as well as in western and central Kenya, Uganda, Rwanda, Burundi, and Belg cropping areas of Ethiopia. There is an elevated flood risk in coastal and southern Tanzania, coastal and western Kenya, parts of eastern and northern Uganda, central Ethiopia and northwestern Somalia, Burundi and Rwanda, and parts of western Yemen. With April being the critical month for most of these areas, rainfall is expected to be fully established across the region in the next two weeks, with cumulatively above-average rainfall likely in most of the region from March 1^st to April 20^th (Figure 4). However, deficits are likely to strengthen in parts of Oromia and Afar in Ethiopia. The rest of the region will likely remain typically dry and sunny.