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Timely onset of Belg season in Ethiopia and long rains in western sector of East Africa

  • Seasonal Monitor
  • East Africa
  • March 10, 2019
Timely onset of Belg season in Ethiopia and long rains in western sector of East Africa

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  • Key Messages
  • Seasonal Progress
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    Key Messages
    • January marked a timely to slightly early onset of seasonal rains in parts of Ethiopia’s Belg-dependent cropping zones and the western sector of East Africa.

    • Meanwhile, much of the eastern Horn remained typically dry with exceptionally hotter-than-normal day and night land surface temperatures. However, localized areas of eastern Kenya and southern Somalia experienced light to moderate rainfall amounts in the past week.

    • The rainfall outlook through March 13 depicts an increased likelihood for continued above-average to average seasonal rainfall over Tanzania as well as the establishment of rainfall in the western sector and Belg-dependent areas. There is increased flood risk in Tanzania’s coastal regions and around the Lake Victoria basin region of Kenya, Tanzania, and Uganda.

    Seasonal Progress

    In early to late February, the onset of the March to May seasonal rains gradually began and spread northwards from Burundi, Rwanda, and Uganda into the Lake Victoria environs and Ethiopia’s Belg cropping zones. This marked a timely to slightly early onset of the cropping season in these areas. According to CHIRPS preliminary satellite-derived data, rainfall accumulation was varied (Figure 1). In Burundi, Rwanda, and western Uganda, amounts were slightly below average. However, the rainfall amounts (>20mm) were sufficient to trigger land preparation and early crop planting. In parts of southeastern and northern Uganda and parts of Ethiopia’s Belg-dependent areas (SNNP, Gambela, Oromia, and Amhara), rainfall ranged from 10 to 100mm above average. In Kenya, there were incidences of well above-average rainfall amounts (>300 percent of average) that led to reports of localized flooding around the Lake Victoria region. In Tanzania, the progression of the Msimu season in February was characterized by above-average accumulation the south and northwest.

    Meanwhile, the eastern Horn remained typically dry, but with significantly hotter-than-normal land surface temperatures throughout February. Day and night-time temperatures were generally exceptionally high in eastern South Sudan and eastern Ethiopia, Somalia, and much of Kenya. In parts of eastern South Sudan, day-time temperatures slightly exceeded 40 C°, while night-time temperatures hovered at 34-36 C°. Day-time temperatures ranged from 32 to 38 C° in the rest of the eastern Horn, resulting into rapid depletion of surface water pans and deterioration of pasture and browse for livestock. Field reports indicate increasing human-wildlife and resource-based conflicts, and there are extensive, on-going wildfires around the Mt. Kenya region.

    According to the eMODIS/Normalized Difference Vegetation Index (NDVI), vegetation conditions are significantly drier-than-normal across much of the eastern Horn as well as in parts of northern and eastern South Sudan, the southwestern and Rift Valley regions of Ethiopia, northeastern Tanzania, and Uganda. However, it should be noted that the recent rains in February are likely to result in gradual improvements in vegetation condition in Uganda, South Sudan, and Belg cropping zones of Ethiopia. In addition, localized areas in eastern Kenya and southern Somalia received unseasonal rains in February that may mitigate current deterioration. Still, much of eastern Horn is likely to remain drier-than-normal until the full onset of the March-May/April-June rains. In contrast, near-average vegetation is expected to continue in most of Tanzania due to the favorable Msimu rains, apart from localized rainfall-deficit areas.

    Recent and on-going field crop assessment reports are indicative of good cropping conditions across Tanzania. However, drought conditions have affected marginal cropping zones in Kenya’s arid and semi-arid lands (ASAL) and much of Somalia, following the below-average Deyr/short-rains and prevailing hotter-than-normal temperatures.

    The following is a country-by-country update on recent seasonal progress to date:

    • In Somalia, significantly drier and hotter-than-normal conditions prevail. Recent post-Deyr 2018 field assessments are indicative of successive drought conditions since 2016/17 with very short-lived recovery periods, causing adverse impacts on pastoral and agropastoral livelihoods. There is an increased likelihood that the current dry conditions and above-average day and night temperatures will continue until the onset of Gu rains in April. However, light to moderate rainfall amounts were reported in localized areas of southern Somalia in February, and the presence of tropical storms in the neighboring Indian Ocean may bring some light to moderate rains and slightly ease conditions in southern coastal areas.
    • In Ethiopia, early seasonal rainfall occurred in February in Belg-dependent SNNP, Oromia, Amhara, and Tigray regions, as well as rainfall in pastoral Afar and northeastern Somali regions. Vegetation conditions have gradually improved, according to NDVI and confirmed by available field reports. However, areas of drier-than-normal vegetation conditions persist, especially along the Rift Valley zones of Ethiopia. With the on-going rains there are reports of timely to early planting in the southwest, and this is likely to spread to northern regions as the rains are established as forecast in March.
    • In Kenya, unimodal seasonal rains are expected to fully establish over western and parts of central Rift Valley areas, and early to timely crop planting is expected. An elevated risk of flooding in flood-prone areas of the Lake region and southern Kenya is expected, and there were already reports of localized flooding around the Lake Victoria region as of late February. In parts of central, eastern, and northwestern Kenya, light to moderate rains are expected to continue this week, but are likely to give way to dry spells into mid-March. The rest of the country likely to remain sunny and dry, leading to further deterioration in rangeland resources. Field reports are indicative of long distance trekking to water sources, livestock migration, and resource-based and human-wildlife conflict in some ASAL counties.
    • In Sudan, typical dry and sunny conditions continued in February. The benefits of above-average seasonal rainfall in 2018 are still evident, according to satellite-derived indicators of vegetation and surface water conditions. Little to no rains are forecast in the coming weeks, given the current dry season. The onset of its main rainfall season will occur in June.
    • In South Sudan, there has been gradual improvement in vegetation conditions over much of eastern and southern South Sudan, as a result of recent moderate to locally heavy rainfall amounts in February. However, the rainfall outlook for the next two weeks is indicative of typical sunny and dry conditions as the dry season continues across the country, apart from the south-eastern regions bordering Turkana County in Kenya and Karamoja region of Uganda.  
    • In Uganda, February marked the onset of bimodal first season rainfall in south-central Uganda and localized areas in the east. Above-average rainfall was confined to its southern districts and around the Lake Victoria basin. Parts of western, central, and northwestern Uganda experienced below-average early seasonal rainfall amounts, and vegetation conditions are relatively drier-than-normal. The seasonal rains are forecast to intensify in March in the south, while northern and eastern Uganda are forecast to remain dry. Unimodal Karamoja is forecast to remain typically dry.
    • In Rwanda and Burundi, season B rainfall is indicative of a timely onset. Although cumulative February rainfall was below-average, amounts were sufficient for land preparation and planting. Vegetation conditions are likely to significantly improve in the coming weeks with full establishment of the seasonal rains in March.
    • In Tanzania, 2018/19 Msimu maize crops are currently in the reproductive stages, and average to above-average yield prospects are expected due to good seasonal rainfall performance. The exception is in northern bimodal regions, which have continued to experience below average and erratic rainfall performance. However, gradual improvement is expected in these regions as the March to May rains are established.
    • In Yemen, February remained typically sunny and dry for much of the country, but with relatively cooler land surface temperatures over the western highland regions.  Light to moderate rains are forecast over the western highland and coastal regions of Yemen for the next two-weeks. Sunny and dry conditions expect to continue for the rest of the country.


    The short-term rainfall outlook through March 13, 2019, depicts the gradual establishment of March to May seasonal rains in Burundi, Rwanda, southern Uganda, parts of southwestern Kenya, and most Belg-dependent cropping zones in Ethiopia.  These rains are attributed to conducive atmospheric and oceanic conditions.

    Light rainfall and slight easing of land surface temperatures are also expected in parts of central, eastern and northwestern Kenya, due to the presence of tropical storms over the neighboring Indian Ocean. However, these are expected to subside by next week and give way to typically dry and sunny conditions through mid-March.

    Intense tropical storm/cyclone activities are expected to result in moderate to very heavy rains across Tanzania for the next two-weeks, with an elevated risk of flooding in eastern, southern and northeastern areas. The risk of flooding is also elevated in a few areas around the Lake Victoria basin and in southern Kenya.

    In the rest of eastern Horn, typical sunny and dry conditions are forecast to continue into mid-March. A timely to early onset of the Gu/Genna/long rains seasonal rains are expected in late March into early April.


    Figure 1

    Source: USGS/FEWS NET

    Figure 2

    Source: USGS/FEWS NET

    Figure 3

    Source: USGS/FEWS NET

    FEWS NET’s Seasonal Monitor reports are produced for Central America and the Caribbean, West Africa, East Africa, Central Asia, and Somalia every 10-to-30 days during the region’s respective rainy season(s). Seasonal Monitors report updates on weather events (e.g., rainfall patterns) and associated impacts on ground conditions (e.g., cropping conditions, pasture and water availability), as well as the short-term rainfall forecast. Find more remote sensing information here.

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